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The human brain effortlessly solves the complex computational task of sound localization using a mixture of spatial cues. How the brain performs this task in naturalistic listening environments (e.g. with reverberation) is not well understood. In the present paper, we build on the success of deep neural net-works at solving complex and high-dimensional problems [1] to develop goal-driven, neurobiological-inspired convolutional neural network (CNN) models of human spatial hearing. After training, we visual-ize and quantify feature representations in intermediate layers to gain insights into the representational mechanisms underlying sound location encoding in CNNs. Our results show that neurobiological-inspired CNN models trained on real-life sounds spatialized with human binaural hearing characteristics can accu-rately predict sound location in the horizontal plane. CNN localization acuity across the azimuth resem-bles human sound localization acuity, but CNN models outperform human sound localization in the back. Training models with different objective functions -that is, minimizing either Euclidean or angular dis-tance -modulates localization acuity in particular ways. Moreover, different implementations of binaural integration result in unique patterns of localization errors that resemble behavioral observations in humans. Finally, feature representations reveal a gradient of spatial selectivity across network layers, starting with broad spatial representations in early layers and progressing to sparse, highly selective spa-tial representations in deeper layers. In sum, our results show that neurobiological-inspired CNNs are a valid approach to modeling human spatial hearing. This work paves the way for future studies combining neural network models with empirical measurements of neural activity to unravel the complex compu-tational mechanisms underlying neural sound location encoding in the human auditory pathway. (c) 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Broad organizational features of the auditory pathway have been replicated by artificial neural networks trained on diverse and naturalistic stimuli. It is credible that neural network analogues could also reveal specific neural computations underlying targeted auditory phenomena. This remains to be established. Here, we examined a modified autoencoder (a deep neural network akin to symbolic regression) trained to imitate an auditory behavior rooted in the binaural system. The behavior promoted the use of split-second interaural timing cues to improve the detection of a tone presented in noise. In the optimal network, we observed the emergence of specialized computations with prominent similarities to animal models. Artificial neurons developed a sensitivity to temporal delays that increased deeper into the network and were widely distributed in preference (extending to delays beyond the range permitted by head width), and the ensuing dynamics were consistent with a binaural cross-correlation mechanism. Our results attest to the generality of these solutions for performing signal detection at low frequencies. Moreover, this is a primary demonstration that deep learning methods can be used to infer tangible mechanisms underlying auditory perception. AUTHOR SUMMARY Do artificial intelligence (AI) systems process sounds in a similar way to the brain? If so, they represent a vital resource with which to investigate sensory systems. Here, we report an AI system that automatically developed auditory computations similar to those described in animal neurophysiology. The network learnt to use subtle discrepancies across its “two ears” to better detect a signal amongst a background noise. In the process, tuning to timing cues and established mechanisms of binaural hearing (relating to the use of both ears) developed internally. The results offer insight into computations occurring in deep brain structures that are difficult to measure with non-invasive techniques. Further, the results endorse informed associations made between AI systems and the auditory brain.

Normal-hearing (NH) listeners rely on two binaural cues, the interaural time (ITD) and level difference (ILD), for azimuthal sound localization. Cochlear-implant (CI) listeners, however, rely almost entirely on ILDs. One reason is that present-day clinical CI stimulation strategies do not convey salient ITD cues. But even when presenting ITDs under optimal conditions using a research interface, ITD sensitivity is lower in CI compared to NH listeners. Since it has recently been shown that NH listeners change their ITD/ILD weighting when only one of the cues is consistent with visual information, such reweighting might add to CI listeners’ low perceptual contribution of ITDs, given their daily exposure to reliable ILDs but unreliable ITDs. Six bilateral CI listeners completed a multi-day lateralization training visually reinforcing ITDs, flanked by a pre- and post-measurement of ITD/ILD weights without visual reinforcement. Using direct electric stimulation, we presented 100- and 300-pps pulse trains at a single interaurally place-matched electrode pair, conveying ITDs and ILDs in various spatially consistent and inconsistent combinations. The listeners’ task was to lateralize the stimuli in a virtual environment. Additionally, ITD and ILD thresholds were measured before and after training. For 100-pps stimuli, the lateralization training increased the contribution of ITDs slightly, but significantly. Thresholds were neither affected by the training nor correlated with weights. For 300-pps stimuli, ITD weights were lower and ITD thresholds larger, but there was no effect of training. On average across test sessions, adding azimuth-dependent ITDs to stimuli containing ILDs increased the extent of lateralization for both 100- and 300-pps stimuli. The results suggest that low-rate ITD cues, robustly encoded with future CI systems, may be better exploitable for sound localization after increasing their perceptual weight via training.

For amplitude-modulated sound, the envelope interaural time difference (ITD(ENV)) is a potential cue for sound-source location. ITD(ENV) is encoded in the lateral superior olive (LSO) of the auditory brainstem, by excitatory-inhibitory (EI) neurons receiving ipsilateral excitation and contralateral inhibition. Between human listeners, sensitivity to ITD(ENV) varies considerably, but ultimately decreases with increasing stimulus carrier frequency, and decreases more strongly with increasing modulation rate. Mechanisms underlying the variation in behavioral sensitivity remain unclear. Here, with increasing carrier frequency (4–10 kHz), as we phenomenologically model the associated decrease in ITD(ENV) sensitivity using arbitrarily fewer neurons consistent across populations, we computationally model the variable sensitivity across human listeners and modulation rates (32–800 Hz) as the decreasing range of membrane frequency responses in LSO neurons. Transposed tones stimulate a bilateral auditory-periphery model, driving model EI neurons where electrical membrane impedance filters the frequency content of inputs driven by amplitude-modulated sound, evoking modulation filtering. Calculated from Fisher information in spike-rate functions of ITD(ENV), for model EI neuronal populations distinctly reflecting the LSO range in membrane frequency responses, just-noticeable differences in ITD(ENV) collectively reproduce the largest variation in ITD(ENV) sensitivity across human listeners. These slow to fast model populations each generally match the best human ITD(ENV) sensitivity at a progressively higher modulation rate, by membrane-filtering and spike-generation properties producing realistically less than Poisson variance. Non-resonant model EI neurons are also sensitive to interaural intensity differences. With peripheral filters centered between carrier frequency and modulation sideband, fast resonant model EI neurons extend ITD(ENV) sensitivity above 500-Hz modulation.

Bilateral cochlear implants (BI-CIs) or a CI for single-sided deafness (SSD-CI; one normally functioning acoustic ear) can partially restore spatial-hearing abilities, including sound localization and speech understanding in noise. For these populations, however, interaural place-of-stimulation mismatch can occur and thus diminish binaural sensitivity that relies on interaurally frequency-matched neurons. This study examined whether plasticity—reorganization of central neural pathways over time—can compensate for peripheral interaural place mismatch. We hypothesized differential plasticity across two systems: none for binaural processing but adaptation for pitch perception toward frequencies delivered by the specific electrodes. Interaural place mismatch was evaluated in 19 BI-CI and 23 SSD-CI human subjects (both sexes) using binaural processing (interaural-time-difference discrimination with simultaneous bilateral stimulation), pitch perception (pitch ranking for single electrodes or acoustic tones with sequential bilateral stimulation), and physical electrode-location estimates from computed-tomography (CT) scans. On average, CT scans revealed relatively little BI-CI interaural place mismatch (26° insertion-angle mismatch) but a relatively large SSD-CI mismatch, particularly at low frequencies (166° for an electrode tuned to 300 Hz, decreasing to 14° at 7000 Hz). For BI-CI subjects, the three metrics were in agreement because there was little mismatch. For SSD-CI subjects, binaural and CT measurements were in agreement, suggesting little binaural-system plasticity induced by mismatch. The pitch measurements disagreed with binaural and CT measurements, suggesting place-pitch plasticity or a procedural bias. These results suggest that reducing interaural place mismatch and potentially improving binaural processing by reprogramming the CI frequency allocation would be better done using CT-scan than pitch information.SIGNIFICANCE STATEMENTElectrode-array placement for cochlear implants (bionic prostheses that partially restore hearing) does not explicitly align neural representations of frequency information. The resulting interaural place-of-stimulation mismatch can diminish spatial-hearing abilities. In this study, adults with two cochlear implants showed reasonable interaural alignment, whereas those with one cochlear implant but normal hearing in the other ear often showed mismatch. In cases of mismatch, binaural sensitivity was best when the same cochlear locations were stimulated in both ears, suggesting that binaural brainstem pathways do not experience plasticity to compensate for mismatch. In contrast, interaurally pitch-matched electrodes deviated from cochlear-location estimates and did not optimize binaural sensitivity. Clinical correction of interaural place mismatch using binaural or computed-tomography (but not pitch) information may improve spatial-hearing benefits.

This paper proposes a binaural-centered mode-matching (BCMM) method that performs sound field reproduction with two reproduction points, one at each ear. A sound field reproduced by higher-order Ambisonics converges to the target field around a sweet spot whose size is inversely proportional to the frequency when the truncated order of the spherical harmonic expansion is constant. By contrast, BCMM translates the spherical harmonic coefficients on the basis of the addition theorem to realize two reproduction points at both ear positions. The BCMM method thereby avoids degradation of reproduction due to a smaller sweet spot at higher frequencies, as occurs with the conventional method, and thereby, leads to an accurate reproduction at higher frequencies. A comparison of numerical simulations of the binaural signals obtained when rendering with BCMM and conventional methods shows that, compared with the conventional method, the BCMM method improves the reproduction accuracy.

This study aims initially to evaluate the quality of different soundscapes in the public space of the city of Biskra, in Algeria. A total of 35 participants took part in a laboratory experiment, where 28 sound clips of one-minute duration taken from public spaces in the city were used as stimuli. The A-weighted equivalent continuous sound pressure level (LAeq,1min) was calculated. The participants rated the quality of the soundscape using attribute scales provided in their own native language. The results of the questionnaire on the recorded soundtracks confirm that the immediate environment affects the ambient sound level and the quality of the sound environment, where the sound environments of the areas located near the roads, with a high mechanical flow, are considered the most unpleasant and noisy, with a high A-weighted equivalent continuous sound pressure level (LAeq,1min). The findings of this study indicate that there are statistically significant correlations between pleasantness and loudness, presence of mechanical sounds, presence of non-mechanical sounds, and a sound exposure level. In addition, this study shows that there is a significant positive correlation between pleasantness and the presence of non-mechanical sounds. The results also showed an inverse relationship between the presence of mechanical and non-mechanical sounds, and that the absence of mechanical sounds allows natural and human sounds to be more audible, making the soundscape more pleasant and calm according to the results of the questionnaire. From this study, the duality LAeq,1min and the components of the soundscape are very representative indicators of the quality of the soundscape.

PurposeThis study examined the relationship between self-perceived hearing abilities and binaural speech-in-noise performance in young to middle-age adults with normal pure-tone hearing.MethodSixty-six adults with normal hearing (thresholds ≤ 25 dB HL at 250–8000 Hz) participated. Self-perceived hearing abilities were assessed using the Adult Auditory Performance Scale (AAPS). The AAPS provides a single global score of self-perceived hearing abilities and individual subscale scores for six listening conditions, namely, Quiet, Ideal, Noise, Multiple Inputs, Auditory Memory, and Auditory Attention. Binaural speech-in-noise performance was measured with the Listening in Spatialized Noise–Sentences Test (LiSN-S).ResultsResults revealed significant correlations between the AAPS and the LiSN-S. Listeners who scored higher on the AAPS (greater self-perceived hearing difficulty) performed poorer on the LiSN-S. The strongest correlations were observed between the AAPS Noise subscale score and the LiSN-S low- and high-cue conditions. Age was significantly correlated with both pure-tone hearing and the LiSN-S spatial advantage, with older participants exhibiting poorer thresholds and smaller spatial advantages. Pure-tone hearing was also significantly correlated with binaural speech-in-noise performance. Listeners with poorer thresholds performed poorer across multiple LiSN-S conditions. Linear regression revealed that a significant amount of the variance in LiSN-S performance was accounted for by pure-tone hearing as well as the AAPS global score and Noise subscale score.ConclusionsResults demonstrate a clear relationship between an individual's self-perceived hearing ability and their binaural speech-in-noise performance. In addition, minimal threshold elevation within the normal range and age (i.e., middle adulthood) had a negative impact on binaural speech-in-noise performance. The results support the inclusion of speech-in-noise testing for all patients, even those whose pure-tone hearing falls within the traditional normal range.

Audiological use of the 40 Hz-ASSR (auditory steady state responses) could be valuable for objectively estimating the frequency-specific threshold in adults undergoing an expertise examination for medicolegal and/or compensation purposes. The present prospective study was set up to clarify the relationship between the thresholds obtained by cortical evoked response audiometry (CERA) and by 40 Hz-ASSR, in the same ears, within a large homogeneous sample of 164 subjects (328 ears) with NIHL and well documented exposure to noise. All these subjects claimed financial compensation for occupational NIHL, and there was a suspicion of exaggeration of the reported NIHLs. ASSR thresholds show a good correlation with the CERA thresholds. However, a systematic shift is noticed, ASSR thresholds being on average (1–2 – 3 kHz) 4.38 dB lower (i.e. showing less hearing loss) than CERA thresholds. Moreover, the binaural multiple ASSR technique allows a considerable time gain when compared to the CERA.

Detection of transient changes in interaural correlation is based on the temporal precision of the central representations of acoustic signals. Whether schizophrenia impairs the temporal precision in the interaural correlation process is not clear. In both participants with schizophrenia and matched healthy-control participants, this study examined the detection of a break in interaural correlation (BIC, a change in interaural correlation from 1 to 0 and back to 1), including the longest interaural delay at which a BIC was just audible, representing the temporal extent of the primitive auditory memory (PAM). Moreover, BIC-induced electroencephalograms (EEGs) and the relationships between the early binaural psychoacoustic processing and higher cognitive functions, which were assessed by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), were examined. The results showed that compared to healthy controls, participants with schizophrenia exhibited poorer BIC detection, PAM and RBANS score. Both the BIC-detection accuracy and the PAM extent were correlated with the RBANS score. Moreover, participants with schizophrenia showed weaker BIC-induced N1-P2 amplitude which was correlated with both theta-band power and inter-trial phase coherence. These results suggested that schizophrenia impairs the temporal precision of the central representations of acoustic signals, affecting both interaural correlation processing and higher-order cognitions.

The paper describes: studio techniques of recording and reproducing audio signals made with an artificial head, differences between stereophony and binaural and details about electroacoustic signal reproduction.

Introduction: Central auditory processing refers to the efficiency and effectiveness with which the central nervous system uses auditory information: it may be altered in neurological disorders and brain injuries, such as strokes. However, despite evidence of probable alterations in the pediatric population, functional abilities and post-stroke limitations are still not well documented in the literature. Objective: To analyze the findings of the electrophysiological and behavioral evaluations of central auditory processing of children and adolescents diagnosed with stroke from a reference outpatient clinic, as well as to investigate possible associations with the variables: type and location of the stroke and age group. Methods: The present study is characterized as comparative cross-sectional. The sample, for convenience, included individuals aged 7–18 years divided into two groups: study group, composed of individuals with a diagnosis of stroke, and control group, composed of individuals with typical development. The evaluation consisted of the following procedures: anamnesis, basic audiological evaluation, behavioral evaluation of the auditory processing disorder (dichotic digit test, dichotic consonant-vowel, synthetic sentence identification/pediatric speech intelligibility, gaps in noise, pitch pattern sequence, masking level difference), and electrophysiological evaluation (P300 and mismatch negativity). Results: Nineteen children and adolescents were included in the study group. The control group was composed of 19 children and adolescents with typical development. In the comparison between the groups, a worse performance is observed for the study group in all the evaluated tests, behavioral and electrophysiological. In the behavioral evaluation of central auditory processing, there was a statistical difference for all tests, except for masking level difference and dichotic digit test, binaural separation step on the left. In the electrophysiological evaluation, there was a statistical difference in the latency of mismatch negativity and P300. No associations were found between the behavioral and electrophysiological findings and the location of the stroke and age group variables. Conclusion: Children and adolescents diagnosed with stroke present a worse performance in the electrophysiological and behavioral evaluations of central auditory processing when compared to a control group. Resumo Introdução: O processamento auditivo central refere-se à eficiência e eficácia com que o sisPotenciais evocados tema nervoso central usa informações auditivas e pode estar alterado em distúrbios neurológicos e lesões cerebrais, como acidentes vasculares cerebrais. No entanto, apesar das evidências de Distúrbios possíveis alterações na população pediátrica, as habilidades funcionais e as limitações pósperceptivos -acidente vascular cerebral ainda não estão bem documentadas na literatura. Objetivo: Analisar os achados das avaliações eletrofisiológicas e comportamentais do procesDoenças auditivas samento auditivo central de crianças e adolescentes diagnosticados com acidente vascular cerebral em um ambulatório de referência, bem como investigar possíveis associações com Criança as variáveis: tipo e localização do acidente vascular cerebral e faixa etária. Método: Estudo transversal comparativo. A amostra, por conveniência, incluiu indivíduos de 7 a 18 anos, divididos em dois grupos: grupo de estudo (GE), composto por indivíduos com diagnóstico de acidente vascular cerebral, e grupo controle (GC), composto por indivíduos com desenvolvimento típico. A avaliação consistiu nos seguintes procedimentos: anamnese, avaliação audiológica básica, avaliação comportamental do distúrbio de processamento auditivo (teste dichotic digit, dichotic consonant-vowel, synthetic sentence identification/pediatric speech intelligibility, gaps in noise, pitch pattern sequence, masking level difference) e avaliação eletrofisiológica (P300 e mismatch negativity -). Resultados: Dezenove crianças e adolescentes foram incluídos no GE. O GC foi composto por 19 crianças e adolescentes com desenvolvimento típico. Na comparação entre os grupos, observa-se pior desempenho para o GE em todos os testes avaliados, comportamentais e eletrofisiológicos. Na avaliação comportamental do processamento auditivo central, houve diferença estatística para todos os testes, exceto masking level difference e teste dichotic digit, na fase de separação binaural na orelha esquerda. Na avaliação eletrofisiológica, houve diferença estatística na latência do mismatch negativity e P300. Não foram encontradas associações entre os achados comportamentais e eletrofisiológicos e as variáveis localização do acidente vascular cerebral e faixa etária. Conclusão: Crianças e adolescentes diagnosticados com acidente vascular cerebral apresentam pior desempenho nas avaliações eletrofisiológicas e comportamentais do processamento auditivo central quando comparados a um grupo controle.

The term “immersive audio” is frequently used to describe an audio experience that provides the listener the sensation of being fully immersed or “present” in a sound scene. This can be achieved via different presentation modes, such as surround sound (several loudspeakers horizontally arranged around the listener), 3D audio (with loudspeakers at, above, and below listener ear level), and binaural audio to headphones. This article provides an overview of two recent standards that support the bitrate-efficient carriage of high-quality immersive sound. The first is MPEG-H 3D audio, which is a versatile standard that supports multiple immersive sound signal formats (channels, objects, and higher order ambisonics) and is now being adopted in broadcast and streaming applications. The second is MPEG-I immersive audio, an extension of 3D audio, currently under development, which is targeted for virtual and augmented reality applications. This will support rendering of fully user-interactive immersive sound for three degrees of user movement [three degrees of freedom (3DoF)], i.e., yaw, pitch, and roll head movement, and for six degrees of user movement [six degrees of freedom (6DoF)], i.e., 3DoF plus translational ${x}$ , ${y}$ , and ${z}$ user position movements.

The performance of the far-field speaker identification (SI) system is usually reduced by the well-known mismatch problem imposed by environmental conditions. Speech enhancement methods are known as convenient ways of resolving the mismatches created by additive noise and reverberations. Human auditory capability for identifying and segregating sounds of speakers in complex environmental conditions motivates researchers to employ known aspects of binaural hearing in speech separation and enhancement methods. This paper proposes a solution to the mismatch problem by employing binaural speech separation methods as front-end processing in the i-vector-based speaker identification. Here, the speech separation approaches utilize binaural masks in their structure to improve the performance of the SI systems by enhancing mixture signals in realistic environmental conditions. For this purpose, two binaural masks, namely, model-based expectation-maximization interaural coherence mask (MEICM) and a recently-introduced DNN-based mask, are employed in the framework of the proposed SI structure. To evaluate the new binaural SI structure, an experiment is conducted which examines various ratio masks in the i-vector-based speaker identification with diffused multi-talker babble noise and reverberation. The simulation results show that employing the DNN-based ratio mask in the binaural speech separation front-end achieves the highest identification performance among other mask estimation methods.

Recent evidences suggest that binaural vestibular stimulation affects tactile temporal processing. However, it remains difficult to determine the physiological mechanisms supporting the vestibular-somatosensory interactions observed during a TOJ task. Controlling the activation of the right or left vestibular system separately could allow to better understand the physiological bases of these findings and reconcile previous studies. The objective of the present study was to examine tactile temporal processing using a temporal order judgment task following selective stimulation of the right and left vestibular system with bi-thermal caloric vestibular stimulation (CVS). A total of 24 right-handed participants received bi-thermal CVS either in the right ear (n = 12) or the left ear (n = 12). Participants held vibrators in both hands which delivered a signal temporally separated by a variable asynchrony. Participants had to report the hand where the vibration was perceived first. The task was performed in three different CVS conditions: (1) baseline, (2) warm CVS, and (3) cold CVS. Analysis of the logistics curve parameters-just noticeable difference (JND) and point of subjective simultaneity (PSS)-for each participant in each CVS conditions revealed an increase in JND greater following warm CVS. A significant increase in JND following warm CVS was measured bilaterally. However, cold CVS increased JND only when CVS was applied in the left ear, but not in the right ear. Finally, no influence of CVS on PSS was observed.

Due to COVID 19, personal protective equipment (PPE) is now used in everyday life. Such PPE affects communication and perception. This paper provides an overview of the impact of PPE on Head Related Transfer Functions (HRTFs) and insertion loss. Spatial acoustic effects of common PPE on human hearing can be documented to improve and inform field worker safety and communication. After a general description of the measurement process and required tools, we focus on a few methods which contribute significantly to the accuracy and analysis of PPE-based HRTF data. The dedicated setup allows measuring a full 360-degree map in automated fashion. It includes a special ring setup with 25 speakers, and a precise turn table that is used to adjust the angle of the device under test with respect to the ring. Binaural measurements were performed on a set of common PPE items on a Head and Torso Simulator (HATS) system, including hard hats, safety glasses, hearing protection, and various face masks. An overview of the data is presented. © INTER-NOISE 2021 .All right reserved.

Binaural synthesis is the most used sound system for diverse virtual and augmented reality systems nowadays, given its simplicity of implementation and the need of using only two audio channels. It is widely used in computer games, auralization and even audio production. To achieve the most natural sound field recreation, systems used for binaural synthesis must include a head-tracking sensor to dynamically calculate the binaural signal for the head orientation at any given moment. This is done by inertial measurement unit (IMU) sensors, specifically the triaxial accelerometers, gyroscopes, and magnetometers. Simpler systems, e.g., Arduino or other embedded systems, provide only raw sensor data, and the orientation is calculated by a processing unit. Other, more complex systems such as smartphones or VR headsets already calculate their position from the raw data using complex sensor integration algorithms. In this paper, a measurement procedure for measuring the precision of IMU sensors is presented. The need of absolute orientation calibration is addressed, and challenges of sensor data drift are discussed. Measurement results for simple embedded systems and complex systems found in smartphones are presented, and an estimation of IMU sensor quality for binaural synthesis is made.

Understanding speech in noise is difficult for individuals with normal hearing and is even more so for individuals with hearing loss. Difficulty understanding speech in noise is one of the primary reasons people seek hearing assistance. Despite amplification, many hearing aid users still struggle to understand speech in noise. In response to this persistent problem, hearing aid manufacturers have invested significantly in developing new solutions. Any solution is not without its tradeoffs, and decisions must be made when optimizing and implementing them. Much of this happens behind the scenes, and casual observers fail to appreciate the nuances of developing new hearing aid technologies. The difficulty of communicating this information to clinicians may hinder the use or the fine-tuning of the various technologies available today. The purpose of this issue of Seminars in Hearing is to educate professionals and students in audiology, hearing science, and engineering about different approaches to combat problems related to environmental and wind noise using technologies that include classification, directional microphones, binaural signal processing, beamformers, motion sensors, and machine learning. To accomplish this purpose, some of the top researchers and engineers from the world's largest hearing aid manufacturers agreed to share their unique insights.

Directionality is the only hearing aid technology — in addition to amplification — proven to help hearing aid users hear better in noise. Hearing aid directionality has been documented to improve speech intelligibility in multiple laboratory studies. In contrast, real-world studies have shown a disconnect between the potential of the technology and what hearing aid users experience in their daily life. This article describes the real-world studies that inspired ReSound to take a different approach to applying directional microphone technology. This approach is based on the idea that hearing aid directionality can leverage natural binaural hearing and inherent listening strategies. The directional strategy includes three listening modes that will be explained. These are the Spatial Cue Preservation mode, the Binaural Listening mode, and the Speech Intelligibility mode. The strategy and the advantages it provides in terms of sound quality, spatial hearing, and improved signal-to-noise ratio with maintained awareness of surroundings are explained.

Binaural rendering is a technique that seeks to generate virtual auditory environments that replicate the natural listening experience, including the three-dimensional perception of spatialized sound sources. As such, real-time knowledge of the listener’s position, or more specifically, their head and ear orientations allow the transfer of movement from the real world to virtual spaces, which consequently enables a richer immersion and interaction with the virtual scene. This study presents the use of a simple laptop integrated camera (webcam) as a head tracker sensor, disregarding the necessity to mount any hardware to the listener’s head. The software was built on top of a state-of-the-art face landmark detection model, from Google’s MediaPipe library for Python. Manipulations to the coordinate system are performed, in order to translate the origin from the camera to the center of the subject’s head and adequately extract rotation matrices and Euler angles. Low-latency communication is enabled via User Datagram Protocol (UDP), allowing the head tracker to run in parallel and asynchronous with the main application. Empirical experiments have demonstrated reasonable accuracy and quick response, indicating suitability to real-time applications that do not necessarily require methodical precision. Furthermore, cross-validation with existing hardware head trackers revealed an adequate agreement on measured head orientation, confirming its potential as a contactless head tracking device.

This study aimed to investigate the temporal processing and binaural interaction functions of central auditory processing tests according to the anatomical localizations of young and elderly individuals. It also sought to evaluate the relationships between the same individuals' central auditory processing tests.This observational and cross-sectional study included individuals with normal hearing between 18 and 30 and 60-75 years of age, who were referred to as the young group and the elderly group, respectively. The evaluation of the central auditory processing tests was completed using the frequency pattern test, duration pattern test, masking level difference test, and random gap detection test. Furthermore, speech discrimination and speech in noise scores were analyzed for both groups.Statistically significant differences were identified between the groups' scores for the speech in noise test, masking level difference test, random gap detection test, frequency pattern test, and duration pattern test (p0.05). A statistically significant relationship was observed between the age and the results of the central auditory processing tests (p0.05).When compared to younger individuals, elderly individuals presented with declined temporal sequences, temporal resolutions, and binaural interaction skills.

Sensory processing abnormalities are a hallmark of autism spectrum disorder (ASD). In the auditory domain, hyper- and hypo-sensitivity to sound, reduced orientation to speech, and difficulty listening in noise are commonly reported. However, the etiology of these auditory processing abnormalities is poorly understood. In this preliminary study, multi-talker speech perception thresholds, otoacoustic emissions, electrophysiological responses, as well as standardized measures of intellectual ability, language, and adaptive function were measured in each individual subject with ASD and their age-matched controls. Speech perception was assessed by estimating target-to-masker ratios at 50% correct for speech targets (0° azimuth) presented with two spatially separated (±45° azimuth) simultaneous speech maskers. The electrophysiological battery used to characterize the transmission and representation of sound included: (1) a click-evoked supra-threshold auditory brainstem response, (2) an envelope following response recorded to a 400-ms-long 4 kHz pure tone carrier amplitude modulated at 100 Hz at two modulations depths (0 and -6 dB) and (3) a binaural evoked interaural phase difference threshold. Together, these measures provide a behavioral and physiological assay of auditory function and show the potential to further our understanding of the mechanisms underlying auditory abnormalities in individuals with ASD.

OBJECTIVE To review our hearing preservation rates and speech recognition outcomes in patients undergoing cochlear implantation with a recently developed lateral wall electrode. STUDY DESIGN Retrospective cohort study. METHODS Retrospective case series of all patients, both pediatric and adult, undergoing cochlear implantation with the Advanced Bionics Hifocus™ SlimJ electrode between December 2017 and January 2020. Main outcomes included hearing preservation rates using several definitions, speech recognition testing primarily through Arizona Biosciences (AzBio) and Consonant-Nucleus-Consonant (CNC) testing, intra- and postoperative complications. RESULTS Sixty-one ears underwent implantation with the new electrode. Hearing preservation rates were 13.0% to 36.0% depending on the definition used. Speech recognition testing showed significant increases from pre- to postoperative condition (Implant-only AzBio: 24.1 to 48.3, P = .004, binaural AzBio: 46.1 to 65.9, P = .002, Implant-only CNC: 9.7 to 35.1, P

The existing speech enhancement algorithm has shown poor performance under low Signal Noise Ratios (SNRs). To resolve this problem, a speech enhancement algorithm based on binaural sound source localization and cosh measure filtering is proposed. Firstly, the algorithm uses a sound source localization algorithm based on head correlation functions and two-level deep learning to extract the spatial information of the binaural sound source and determine the spatial position of the sound source. The beamforming method is then used to remove the noises in different directions from the speech. Finally, the Wiener filtering of cosh measure based on logarithmic relation is used to remove the noise in the same direction as the speech to achieve speech enhancement. Experiments show that the proposed algorithm has better robustness and denoising ability than the contrast algorithms.

Introduction: The pattern of brain waves in primary insomniacs is different from healthy subjects. Studies have shown that binaural beats can alter the pattern of brain waves in healthy individuals, but the efficacy of binaural beats in altering the pattern of brain waves in primary insomniacs has not yet been investigated. The purpose of this study was to evaluate the efficacy of theta binaural beat on the absolute power of theta activity in primary insomniacs. Methods: This study was a randomized clinical trial with experimental and control groups. Primary insomniacs received theta binaural beats in the experimental group and white noise in the control group. Their brain waves were recorded by EEG for 25 minutes, the first 5 minutes without stimulus (1st block), 15 minutes after receiving stimulus (binaural beat or white noise), and the last 5 minutes without stimulus (5th block). Matlab software (R2019a), EEGLAB toolbox and SPSS-24 were used for data analysis. Results: The absolute power of theta activity in the experimental group was significantly higher in the last block comparing to the first block in all brain lobes (P< 0.05). The largest changes in theta activity were in temporal and parietal lobes, and the last one was in prefrontal lobe. In the control group, none of the brain lobes showed significant difference in the last block compared to the first block. Conclusion: Theta binaural beat can alter the absolute power of theta activity in primary insomniacs. The implications of the study are discussed.

Binaural system is an audio technology which relatively easy to apply these days. This was due to the growth in technology developments of the audio recording system. The application of this system is not well known in Indonesia. This was aligned with public assumption where Wayang Kulit performance are one of many unappreciated forms of arts in Indonesia. The main problem that occurred is that whether the binaural system conjoined with the Virtual Reality (VR) System can make the public more appreciate the art form of Indonesian Wayang Kulit. By using the theory of perception conjoin with the binaural technology, it can be assumed that the audience can have a new experience from the performance through the VR thus elevating their appreciation for the art itself. This research will be divided into three stages. The first stage focused on the application of the binaural system on Wayang Kulit Animation through VR system. The second stage will focus on the product assessment whether it can elevate the appreciation of the audience for the art itself. The third stage will focus on applying the binaural system on other Indonesian art form. This year, the research will begin at the first stage.

Neuroscientific and clinical studies on auditory perception often use headphones to limit sound interference. In these conditions, sounds are perceived as internalized because they lack the sound-attributes that normally occur with a sound produced from a point in space around the listener. Without the spatial attention mechanisms that occur with localized sounds, auditory functional assessments could thus be underestimated. We hypothesize that adding virtually externalization and localization cues to sounds through headphones enhance sound discrimination in both healthy participants and patients with a disorder of consciousness (DOC). Hd-EEG was analyzed in 14 healthy participants and 18 patients while they listened to self-relevant and irrelevant stimuli in two forms: diotic (classic sound presentation with an “internalized” feeling) and convolved with a binaural room impulse response (to create an “externalized” feeling). Convolution enhanced the brains’ discriminative response as well as the processing of irrelevant sounds itself, in both healthy participants and DOC patients. For the healthy participants, these effects could be associated with enhanced activation of both the dorsal (where/how) and ventral (what) auditory streams, suggesting that spatial attributes support speech discrimination. Thus, virtually spatialized sounds might “call attention to the outside world” and improve the sensitivity of assessment of brain function in DOC patients.

Mismatch negativity (MMN) is an intensively studied event-related potential component that reflects pre-attentive auditory processing. Existing spatial MMN (sMMN) studies usually use loud-speakers in different locations or deliver sound with binaural localization cues through earphones to elicit MMN, which either was practically complicated or sounded unnatural to the subjects. In the present study, we generated head related transfer function (HRTF)-based spatial sounds and verified that the HRTF-based sounds retained the left and the right spatial localization cues. We further used them as deviants to elicit sMMN with conventional oddball paradigm. Results showed that sMMN was successfully elicited by the HRTF-based deviants in 18 of 21 healthy subjects in two separate sessions. Furthermore, the left deviants elicited higher sMMN amplitudes in the right hemisphere compared to the left hemisphere, while the right deviants elicited sMMN with similar amplitudes in both hemispheres, which supports a combination of contralateral and right-hemispheric dominance in spatial auditory information processing. In addition, the sMMN in response to the right deviants showed good test-retest reliability, while the sMMN in response to the left deviants had weak test-retest reliability. These findings implicate that HRTF-based sMMN could be a robust paradigm to investigate spatial localization and discrimination abilities.

Purpose The purpose of this study is to use variability on tests of basic auditory processing to allow identification of those tests that could be used clinically to describe functional hearing ability beyond the pure-tone audiogram and clinical speech-in-noise tests. Method Psychoacoustic tests implemented using the Portable Automated Rapid Testing system on a calibrated iPad were evaluated for nine young normal-hearing participants ( M age = 21.3, SD = 2.5) and seven hearing-impaired participants ( M age = 64.9, SD = 13.5). Participants completed 10 psychoacoustic subtests in a quiet room. Correlational analyses were used to compare performance on the psychoacoustic test battery with performance on a clinical speech-in-noise test and with the 4-frequency pure-tone average (4FreqPTA). Results Spectral processing ability was highly correlated with 4FreqPTA, and temporal processing ability showed minimal variability across the hearing-impaired group. Tests involving binaural processing captured variability across hearing-impaired listeners not associated with 4FreqPTA or speech-in-noise performance. Conclusions Tests that capture the ability to use binaural cues may add information to what current clinical protocols reveal about patients with auditory complaints. Further testing with a larger sample size is needed to confirm the need for binaural measurements and to develop normative data for clinical settings.

Summary Objective To determine whether an association exists between auditory skills and the reliability of judgments of the vocal deviation grade and the degrees of roughness and breathiness and to evaluate whether these skills are predictive of interrater reliability in auditory-perceptual evaluations. Methods The sample consisted of 20 speech-language pathology students without previous training in auditory-perceptual evaluation. The students underwent a basic audiological evaluation and a central auditory processing evaluation. They then participated in two auditory-perceptual evaluation sessions assessing the general grade (GG) and the degrees of roughness and breathiness of 44 samples of sustained vowel production with the presence or absence of dysphonia. For statistical analysis, the intraclass correlation coefficient (ICC) and a beta regression model were used. Results A difference was found in the average ICCs of the GG parameter between listeners with high and low temporal resolution and binaural interaction skills. Temporal resolution skills and binaural interaction affected the ICC of listeners in the GG evaluation, reducing the likelihood of reliability by 2.8 and 3.6 times, respectively. Conclusion An association exists between temporal resolution skills and binaural interaction and the reliability of listeners in evaluations of vocal deviation severity. Listeners with low levels of these skills show less reliability in evaluations of the severity of vocal deviation. In addition, temporal resolution and binaural interaction are predictors and explain 42.7% of the variability in the reliability of evaluations of vocal deviation severity.

To understand the principal functioning of binaural beats signals and the way it can affect the brain, eight drugs were used. This study was carried out on three groups: the first one contains four binaural beats signals, each one refers to a specific tone: alpha, beta, theta, and delta waves. The second group holds three records, representing three separate meditation binaural beats; however, the third one contains only one record that stands for the Marijuana e-drugs. Two types of analyses were performed on these groups, the temporal and the frequency analyses. In the first one, Hilbert transform was used to detect the envelope of the signal; we then determined the cross correlation function to understand the relationship between the two signals of the left and the right ears. However, in the frequency analysis, Fast Fourier Transform (FFT) was applied to extract binaural and carrier frequencies. The obtained results are very satisfactory and show that there is a delay between the two signals of the left and the right ears. Nevertheless, the frequency analysis shows that in the second group, Solfeggio frequencies lambda, theta and delta waves are used to obtain the meditation state, were gamma, lambda, alpha, and delta waves are applied to get the Marijuana effect in the third group.

OBJECTIVES: To investigate the role of auditory cues for spatial release from masking (SRM) in children with bilateral cochlear implants (BiCIs) and compare their performance with children with normal hearing (NH). To quantify the contribution to speech intelligibility benefits from individual auditory cues: head shadow, binaural redundancy, and interaural differences; as well as from multiple cues: SRM and binaural squelch. To assess SRM using a novel approach of adaptive target-masker angular separation, which provides a more functionally relevant assessment in realistic complex auditory environments. DESIGN: Children fitted with BiCIs (N=11) and with NH (N=18) were tested in virtual acoustic space (VAS) that was simulated using head-related transfer functions (HRTFs) measured from individual children with BiCIs behind the ear and from a standard head and torso simulator for all NH children. In Experiment I, by comparing speech reception thresholds (SRT) across four test conditions that varied in target-masker spatial separation (co-located vs. separated at 180-degree) and listening conditions (monaural vs. binaural/bilateral listening), intelligibility benefits were derived for individual auditory cues for SRM. In Experiment II, SRM was quantified using a novel measure to find the minimum angular separation (MAS) between the target and masker to achieve a fixed 20% intelligibility improvement. Target speech was fixed at either +90 or −90-degree azimuth on the side closer to the better ear (+90-degree for all NH children) and masker locations were adaptively varied. RESULTS: In Experiment I, children with BiCIs as a group had smaller intelligibility benefits from head shadow than NH children. No group difference was observed in benefits from binaural redundancy or interaural difference cues. In both groups of children, individuals who gained a larger benefit from interaural differences relied less on monaural head shadow, and vice versa. In Experiment II, all children with BiCIs demonstrated measurable MAS thresholds < 180-degree and on average larger than that from NH children. Eight of 11 children with BiCIs and all NH children had a MAS threshold < 90-degree, requiring interaural differences only to gain the target intelligibility benefit; whereas the other three children with BiCIs had a MAS between 120 and 137-degree, requiring monaural head shadow for SRM. CONCLUSIONS: When target and maskers were separated at 180-degree on opposing hemifields, children with BiCIs demonstrated greater intelligibility benefits from head shadow and interaural differences than previous literature showed with a smaller separation. Children with BiCIs demonstrated individual differences in using auditory cues for SRM. From the MAS thresholds, more than half of the children with BiCIs demonstrated robust access to interaural differences without needing additional monaural head shadow for SRM. Both experiments led to the conclusion that individualized fitting strategies in the bilateral devices may be warranted to maximize spatial hearing for children with BiCIs in complex auditory environments.

OBJECTIVES Over the past decade, U.S. Department of Defense and Veterans Affairs audiologists have reported large numbers of relatively young adult patients who have normal to near-normal audiometric thresholds but who report difficulty understanding speech in noisy environments. Many of these service members also reported having experienced exposure to explosive blasts as part of their military service. Recent studies suggest that some blast-exposed patients with normal to near-normal-hearing thresholds not only have an awareness of increased hearing difficulties, but also poor performance on various auditory tasks (sound source localization, speech recognition in noise, binaural integration, gap detection in noise, etc.). The purpose of this study was to determine the prevalence of functional hearing and communication deficits (FHCD) among healthy Active-Duty service men and women with normal to near-normal audiometric thresholds. DESIGN To estimate the prevalence of such FHCD in the overall military population, performance of roughly 3400 Active-Duty service members with hearing thresholds mostly within the normal range were measured on 4 hearing tests and a brief 6-question survey to assess FHCD. Subjects were subdivided into 6 groups depending on the severity of the blast exposure (3 levels: none, far away, or close enough to feel heat or pressure) and hearing thresholds (2 levels: audiometric thresholds of 20 dB HL or better, slight elevation in 1 or more thresholds between 500 and 4000 Hz in either ear). RESULTS While the probability of having hearing difficulty was low (≈4.2%) for the overall population tested, that probability increased by 2 to 3 times if the service member was blast-exposed from a close distance or had slightly elevated hearing thresholds (>20 dB HL). Service members having both blast exposure and mildly elevated hearing thresholds exhibited up to 4 times higher risk for performing abnormally on auditory tasks and more than 5 times higher risk for reporting abnormally low ratings on the subjective questionnaire, compared with service members with no history of blast exposure and audiometric thresholds ≤20 dB HL. Blast-exposed listeners were roughly 2.5 times more likely to experience subjective or objective hearing deficits than those with no-blast history. CONCLUSIONS These elevated rates of abnormal performance suggest that roughly 33.6% of Active-Duty service members (or approximately 423,000) with normal to near-normal-hearing thresholds (i.e., H1 profile) are at some risk for FHCD, and about 5.7% (approximately 72,000) are at high risk, but are currently untested and undetected within the current fitness-for-duty standards. Service members identified as "at risk" for FHCD according to the metrics used in the present study, in spite of their excellent hearing thresholds, require further testing to determine whether they have sustained damage to peripheral and early-stage auditory processing (bottom-up processing), damage to cognitive processes for speech (top-down processing), or both. Understanding the extent of damage due to noise and blast exposures and the balance between bottom-up processing deficits and top-down deficits will likely lead to better therapeutic strategies.

Binaural beats have been used as a way of modifying cognition via auditory stimulation. A recent meta-analysis suggests that binaural beat stimulation can have a positive effect on attention (Garcia-Argibay et al., Psychologische Forschung 83:1124-1136, 2019a, Psychological Research Psychologische Forschung 83:357-372, 2019b), with the sample-weighted average effect size being about .58. This is an intriguing and potentially useful finding, both theoretically and practically. In this study, we focus on sustained attention. We delivered beta-frequency (16 Hz) binaural beat stimulation during a sustained attention task. In "Experiment 1", reaction times were faster under beat stimulation than control stimulation in a between-subjects design. However, the effect was modest in magnitude, and model comparisons using Bayes Factors were indiscriminate between including and excluding the effect from the model. We followed this initial experiment with two concurrently administered follow-up experiments. In "Experiment 2", we added thought probes to measure any changes in task engagement associated with binaural beat stimulation. "Experiment 2" revealed a different effect from "Experiment 1": participants in the binaural beat condition exhibited a shallower vigilance decrement. However, the beat stimulation did not affect the thought probes responses. Combining data across the two experiments indicated rather strong evidence against the hypothesis that beta-frequency binaural beats can augment sustained attention, either via a general speeding of responding or a mitigation of the vigilance decrement. Finally, in "Experiment 3", we investigated whether pupillary measures of arousal and/or task engagement would be affected by binaural beat stimulation. There was no evidence for such effects. Overall, we did not observe any consistent evidence that binaural beat stimulation can augment sustained attention or its subjective and physiological correlates.

The modified rhyme test [MRT; House, Williams, Hecker, and Kryter. (1965). J. Acoust. Soc. Am. 37, 158–166] is a widely used test for measuring the intelligibility of communication systems [ANSI (2009). S3.2 (American National Standards Institute, New York)] but has never gained widespread acceptance as a clinical test of speech intelligibility for listeners who are hearing impaired (HI). In this study, a clinical version of the MRT consisting of two 80-word lists was developed and tested on 2394 service members with varying levels of hearing loss. The test used a factorial design incorporating two speech levels [70 and 78 dB sound pressure level (SPL)], two signal-to-noise ratios (+4 and −4 dB), and two binaural conditions (diotic and binaural). High-frequency emphasis reduced the impact of audibility for HI listeners, focusing the test on the distortion component of hearing loss. The results show that listeners with normal hearing (NH) obtained an average score of 80% correct on the MRT80 test. Listeners with a moderate hearing impairment scored an average of 70% correct. The overall level had little impact on performance for either NH or HI listeners. The results demonstrate that the MRT80 test could be a useful test to assess the distortion effects of hearing loss on speech intelligibility, particularly in cases where it is desirable to use a closed-set test for automatic administration.

For abruptly gated sound, interaural time difference (ITD) cues at onset carry greater perceptual weight than those following. This research explored how envelope shape influences such carrier ITD weighting. Experiment 1 assessed the perceived lateralization of a tonal binaural beat that transitioned through ITD (diotic envelope, mean carrier frequency of 500 Hz). Listeners' left/right lateralization judgments were compared to those for static-ITD tones. For an 8 Hz sinusoidally amplitude-modulated envelope, ITD cues 24 ms after onset well-predicted reported sidedness. For an equivalent-duration "abrupt" envelope, which was unmodulated besides 20-ms onset/offset ramps, reported sidedness corresponded to ITDs near onset (e.g., 6 ms). However, unlike for sinusoidal amplitude modulation, ITDs toward offset seemingly also influenced perceived sidedness. Experiment 2 adjusted the duration of the offset ramp (25-75 ms) and found evidence for such offset weighting only for the most abrupt ramp tested. In experiment 3, an ITD was imposed on a brief segment of otherwise diotic filtered noise. Listeners discriminated right- from left-leading ITDs. In sinusoidal amplitude modulation, thresholds were lowest when the ITD segment occurred during rising amplitude. For the abrupt envelope, the lowest thresholds were observed when the segment occurred at either onset or offset. These experiments demonstrate the influence of envelope profile on carrier ITD sensitivity.

Bilateral cochlear-implant (CI) users struggle to understand speech in noisy environments despite receiving some spatial-hearing benefits. One potential solution is to provide acoustic beamforming. A headphone-based experiment was conducted to compare speech understanding under natural CI listening conditions and for two non-adaptive beamformers, one single beam and one binaural, called “triple beam,” which provides an improved signal-to-noise ratio (beamforming benefit) and usable spatial cues by reintroducing interaural level differences. Speech reception thresholds (SRTs) for speech-on-speech masking were measured with target speech presented in front and two maskers in co-located or narrow/wide separations. Numerosity judgments and sound-localization performance also were measured. Natural spatial cues, single-beam, and triple-beam conditions were compared. For CI listeners, there was a negligible change in SRTs when comparing co-located to separated maskers for natural listening conditions. In contrast, there were 4.9- and 16.9-dB improvements in SRTs for the beamformer and 3.5- and 12.3-dB improvements for triple beam (narrow and wide separations). Similar results were found for normal-hearing listeners presented with vocoded stimuli. Single beam improved speech-on-speech masking performance but yielded poor sound localization. Triple beam improved speech-on-speech masking performance, albeit less than the single beam, and sound localization. Thus, triple beam was the most versatile across multiple spatial-hearing domains.

Background Digits-in-noise (DIN) tests have become popular for hearing screening over the past 15 years. Several recent studies have highlighted the potential utility of DIN as a school-aged hearing test. However, age may influence test performance in children due to maturation. In addition, a new antiphasic stimulus paradigm has been introduced, allowing binaural intelligibility level difference (BILD) to be measured by using a combination of conventional diotic and antiphasic DIN. Purpose This study determined age-specific normative data for diotic and antiphasic DIN, and a derived measure, BILD, in children. A secondary aim evaluated the validity of DIN as a smartphone self-test in a subgroup of young children. Research Design A cross-sectional, quantitative design was used. Participants with confirmed normal audiometric hearing were tested with a diotic and antiphasic DIN. During the test, arrangements of three spoken digits were presented in noise via headphones at varying signal-to-noise ratio (SNR). Researchers entered each three-digit spoken sequence repeated by the participant on a smartphone keypad. Study Sample Overall, 621 (428 male and 193 female) normal hearing children (bilateral pure tone threshold of ≤ 20 dB hearing level at 1, 2, and 4 kHz) ranging between the ages of 6 and 13 years were recruited. A subgroup of 7-year-olds (n = 30), complying with the same selection criteria, was selected to determine the validity of self-testing. Data Collection and Analysis DIN testing was completed via headphones coupled to a smartphone. Diotic and antiphasic DIN speech recognition thresholds (SRTs) were analyzed and compared for each age group. BILD was calculated through subtraction of antiphasic from diotic SRTs. Multiple linear regressions were run to determine the effect of age on SRT and BILD. In addition, piecewise linear regressions were fit across different age groups. Wilcoxon signed-rank tests were used to determine differences between self- and facilitated tests. Results Age was a significant predictor, of both diotic and antiphasic DIN SRTs (p 0.05). Conclusions Increasing age was significantly associated with improved SRT and BILD using diotic and antiphasic DINs. DIN could be used as a smartphone self-test in young children from 7 years of age with appropriate quality control measures to avoid potential false positives.