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Temporal-sampling theory argues that difficulties in the processing of syllable stress auditory markers and in lexical stress discrimination contribute to explaining the language problems of children with developmental language disorder and of those with dyslexia. The theory has not been tested in other developmental disabilities. This research sought to assess the potential of temporal-sampling theory as a framework to accounting for language difficulties in Down syndrome (DS). Thresholds for auditory markers of lexical stress, lexical stress discrimination, and receptive vocabulary were studied in teenagers and young adults with DS and in peers with other intellectual disability (ID) of unknown origin matched on chronological age and non-verbal cognition. Frequency and intensity thresholds were higher in participants with DS, and their lexical stress discrimination and receptive vocabulary skills were lower than those of the group with other ID. Lexical stress discrimination was predicted by intensity thresholds and group, while receptive vocabulary was only predicted by lexical stress discrimination. The results suggest that temporal-sampling theory is useful to explain language difficulties in individuals with DS or with other ID. This opens up new window opportunities for the design of language intervention programs in such populations. • Temporal-sampling theory was used to explain language in DS. • Lexical stress discrimination was lower in DS than in peers with other ID. • Frequency and intensity thresholds were higher in DS. • Intensity thresholds and group predicted lexical stress discrimination. • Receptive vocabulary was explained by lexical stress discrimination. [ABSTRACT FROM AUTHOR]

Most human auditory psychophysics research has historically been conducted in carefully controlled environments with calibrated audio equipment, and over potentially hours of repetitive testing with expert listeners. Here, we operationally define such conditions as having high 'auditory hygiene'. From this perspective, conducting auditory psychophysical paradigms online presents a serious challenge, in that results may hinge on absolute sound presentation level, reliably estimated perceptual thresholds, low and controlled background noise levels, and sustained motivation and attention. We introduce a set of procedures that address these challenges and facilitate auditory hygiene for online auditory psychophysics. First, we establish a simple means of setting sound presentation levels. Across a set of four level-setting conditions conducted in person, we demonstrate the stability and robustness of this level setting procedure in open air and controlled settings. Second, we test participants' tone-in-noise thresholds using widely adopted online experiment platforms and demonstrate that reliable threshold estimates can be derived online in approximately one minute of testing. Third, using these level and threshold setting procedures to establish participant-specific stimulus conditions, we show that an online implementation of the classic probe-signal paradigm can be used to demonstrate frequency-selective attention on an individual-participant basis, using a third of the trials used in recent in-lab experiments. Finally, we show how threshold and attentional measures relate to well-validated assays of online participants' in-task motivation, fatigue, and confidence. This demonstrates the promise of online auditory psychophysics for addressing new auditory perception and neuroscience questions quickly, efficiently, and with more diverse samples. Code for the tests is publicly available through Pavlovia and Gorilla. [ABSTRACT FROM AUTHOR]

This study was performed to assess whether there is an association between elevated Fasting Blood Glucose (FBG) and hearing impairment in Bangladeshi population. A total of 142 subjects (72 with elevated FBG; 70 control) were included in the study. The mean auditory thresholds of the control subjects at 1, 4, 8 and 12 kHz frequencies were 6.35 ± 0.35, 10.07 ± 0.91, 27.57 ± 1.82, 51.28 ± 3.01 dB SPL (decibel sound pressure level), respectively and that of the subjects with elevated FBG were 8.33 ± 0.66, 14.37 ± 1.14, 38.96 ± 2.23, and 71.11 ± 2.96 dB, respectively. The auditory thresholds of the subjects with elevated FBG were significantly (p 10 years) showed significantly (p 40 years) and younger (≤40 years) age groups compared to the respective controls. The binary logistic regression analysis showed a 5.79-fold increase in the odds of extra-high frequency hearing impairment in diabetic subjects after adjustment for age, gender and BMI. This study provides conclusive evidence that auditory threshold at an extra-high frequency could be a sensitive marker for hearing impairment in diabetic subjects.

Background: The aim of the present study was to compare the hearing thresholds between pure tone audiometry (PTA) and auditory brainstem response (ABR) from level-specific (LS) CE-Chirp® and click stimuli in normal adult subjects. Materials and Methods: Twenty-four adults with normal audiometric thresholds participated in the study. The ABR was recorded from the study participants at 80 dBnHL until their respective auditory thresholds using both the LS CE-Chirp® and click stimuli. Study Design and Statistical Analysis: A quasi-experimental study design was used. Audiometric thresholds (low frequencies [LFs], mid frequencies [MFs], and high frequencies [HFs]) and the ABR thresholds from both stimuli were compared using the Friedman test with Wilcoxon signed-rank test as the post hoc analysis. Results: No statistically significant difference was identified between the PTA and the ABR to LS CE-Chirp® thresholds at LFs and only small differences (<6 dB) median thresholds differences were identified at the MFs and HF. The amplitudes of wave III and V were larger for ABR to LS CE-Chirp® as compared to the ABR from the click stimulus. Conclusion: This study concluded that the ABR to LS CE-Chirp® has closer thresholds than the audiogram as compared to the ABR from click in normal-hearing adult subjects. At the suprathreshold (80 dBnHL), the ABR amplitudes of wave III, and V were larger in LS CE-Chirp® than the click stimulus. [ABSTRACT FROM AUTHOR]

Vocalizations play a critical role in mate recognition and mate choice in a number of taxa, especially, but not limited to, orthopterans, frogs, and birds. But receivers can only recognize and prefer sounds that they can hear. Thus a fundamental question linking neurobiology and sexual selection asks—what is the threshold for detecting acoustic sexual displays? In this study, we use 3 methods to assess such thresholds in túngara frogs: behavioral responses, auditory brainstem responses, and multiunit electrophysiological recordings from the midbrain. We show that thresholds are lowest for multiunit recordings (ca. 45 dB SPL), and then for behavioral responses (ca. 61 dB SPL), with auditory brainstem responses exhibiting the highest thresholds (ca. 71 dB SPL). We discuss why these estimates differ and why, as with other studies, it is unlikely that they should be the same. Although all of these studies estimate thresholds they are not measuring the same thresholds; behavioral thresholds are based on signal salience whereas the 2 neural assays estimate physiological thresholds. All 3 estimates, however, make it clear that to have an appreciation for detection and salience of acoustic signals we must listen to those signals through the ears of the receivers. [ABSTRACT FROM AUTHOR]

Abstract In seasonal breeders, there are behavioral, endocrine, and neural adaptations that promote the sexual receptivity of females and tune their sensory systems to detect and discriminate among advertising males and to successfully copulate. What happens immediately after this key life history event is unclear, but this transitional moment offers a window into the mechanisms that remodel sexual phenotypes. In this study of wild female Cope's gray treefrogs (Hyla chrysoscelis), we tested the hypothesis that oviposition results in a suite of coordinated changes in the sexual phenotype. Specifically, we predicted that sexual receptivity and discrimination behaviors would decline along with circulating concentrations of steroid hormones (corticosterone, estradiol, testosterone) and auditory sensitivity to the acoustic frequencies emphasized in male advertisement calls. We conducted these trait measurements before and after oviposition (ca. 24-h period). There was a 100% decrease in behavioral responsiveness after oviposition, and the concentrations of all three steroids plummeted during this brief window of time, especially testosterone. Moreover, higher concentrations of corticosterone—an important component of the endocrine stress response—were associated with longer response latencies, suggesting that adrenal hormones should be considered in future studies on the hormonal basis of mate choice. Counter to our prediction, auditory sensitivity increased following oviposition, and the amplitude of the auditory brainstem response was influenced by concentrations of estradiol. In pre-oviposition females auditory sensitivity diminished with increasing estradiol concentrations, while sensitivity increased with increasing estradiol concentrations in post-oviposition females, suggesting non-linear estrogenic modulation of peripheral auditory neural recruitment. Overall, our results indicate that there is considerable remodeling of behavioral output following oviposition that co-occurs with changes in both endocrine and sensory physiology. Highlights • Many seasonal breeders transition rapidly from reproductive to non-reproductive. • We measured auditory, hormonal and behavioral traits in frogs during this shift. • Peripheral auditory sensitivity increased after breeding. • Three plasma steroid hormones and behavior declined dramatically after breeding. • Overall, breeding induces rapid and coordinated phenotypic remodeling. [ABSTRACT FROM AUTHOR]

Context: The ability to detect important auditory signals while performing visual tasks may be further compounded by background chatter. Thus, it is important to know how task performance may interact with background chatter to hinder signal detection. Aim: To examine any interactive effects of speech spectrum noise and task performance on the ability to detect signals. Settings and Design: The setting was a sound-treated booth. A repeated measures design was used. Materials and Methods: Auditory thresholds of 20 normal adults were determined at 0.5, 1, 2 and 4 kHz in the following conditions presented in a random order: (1) quiet with attention; (2) quiet with a visuo-spatial task or puzzle (distraction); (3) noise with attention and (4) noise with task. Statistical Analysis: Multivariate analyses of variance (MANOVA) with three repeated factors (quiet versus noise, visuo-spatial task versus no task, signal frequency). Results: MANOVA revealed significant main effects for noise and signal frequency and significant noise–frequency and task–frequency interactions. Distraction caused by performing the task worsened the thresholds for tones presented at the beginning of the experiment and had no effect on tones presented in the middle. At the end of the experiment, thresholds (4 kHz) were better while performing the task than those obtained without performing the task. These effects were similar across the quiet and noise conditions. Conclusion: Detection of auditory signals is difficult at the beginning of a distracting visuo-spatial task but over time, task learning and auditory training effects can nullify the effect of distraction and may improve detection of high frequency sounds.

BACKGROUND: The visual reinforcement audiometry and steady-state evoked potential are tests that allow to identify auditory thresholds. OBJECTIVE: To compare the date obtained throw the visual reinforcement audiometry and the steady-state evoked potential in the determination of the auditory threshold in pediatric patients. MATERIAL AND METHOD: A cross-sectional, comparative, observational and descriptive study was done from February to September 2017 in children participating in a visual reinforcement audiometry and a steady-state evoked potential in 500, 1000, 2000 and 4000 Hz. Descriptive statistic tests and error graphs were also performed to evaluate the trend of the data, t-Student test to determine significant difference for samples related to p < 0.05, confidence intervals for the mean and probabilistic intersection of AꓵB. RESULTS: In most evaluations, the values are inverse with respect to the averages and standard deviations. The highest correlations were found in the frequency of 2000 Hz with TDH39. The probability of greater coincidence between both tests with TDH39 and free field was found in the right ear at the frequency of 500 Hz. CONCLUSIONS: It is necessary to perform the visual reinforcement audiometry in a random way in both ears and evaluated frequencies in order to obtain specific results in the auditory threshold determination, as well as to try to ensure an adequate previous conditioning. [ABSTRACT FROM AUTHOR]

Objectives: Dietary carotenoids lutein (L) and zeaxanthin (Z) have been linked to improved visual and cognitive function. These effects are thought to be mediated by the presence of these pigments in critical regions of the retina and brain. There, it has been postulated that L and Z mediate improved performance by enhancing neural efficiency. The auditory system also relies on efficient segregating of signals and noise and LZ are also found in the auditory cortex. The purpose of the present study was to investigate the influence of LZ status (as assessed by the measuring levels in retina) on auditory thresholds in young non-smokers (N = 32,M = 20.72 ± 3.28 years). Design: LZ status was determined by measuring macular pigment (MP) optical density using a standardized psychophysical technique (customized heterochromatic flicker photometry). Auditory thresholds were assessed with puretone thresholds and puretone auditory thresholds in white noise. Results: MP density was related to many, but not all, of the puretone thresholds we tested: 250 Hz (F(6,32) = 4.36,P < 0.01), 500 Hz (F(6,32) = 2.25,P < 0.05), 1000 Hz (F(6,32) = 3.22,P < 0.05), and 6000 Hz (F(6,32) = 2.56,P < 0.05). Conclusion: The overall pattern of results is consistent with a role for L and Z in maintaining optimal auditory function. [ABSTRACT FROM AUTHOR]

Context: The ability to detect important auditory signals while performing visual tasks may be further compounded by background chatter. Thus, it is important to know how task performance may interact with background chatter to hinder signal detection.Aim: To examine any interactive effects of speech spectrum noise and task performance on the ability to detect signals.Settings and Design: The setting was a sound-treated booth. A repeated measures design was used.Materials and Methods: Auditory thresholds of 20 normal adults were determined at 0.5, 1, 2 and 4 kHz in the following conditions presented in a random order: (1) quiet with attention; (2) quiet with a visuo-spatial task or puzzle (distraction); (3) noise with attention and (4) noise with task.Statistical Analysis: Multivariate analyses of variance (MANOVA) with three repeated factors (quiet versus noise, visuo-spatial task versus no task, signal frequency).Results: MANOVA revealed significant main effects for noise and signal frequency and significant noise-frequency and task-frequency interactions. Distraction caused by performing the task worsened the thresholds for tones presented at the beginning of the experiment and had no effect on tones presented in the middle. At the end of the experiment, thresholds (4 kHz) were better while performing the task than those obtained without performing the task. These effects were similar across the quiet and noise conditions.Conclusion: Detection of auditory signals is difficult at the beginning of a distracting visuo-spatial task but over time, task learning and auditory training effects can nullify the effect of distraction and may improve detection of high frequency sounds. [ABSTRACT FROM AUTHOR]

Introduction ASSR allow frequency-specific evaluation in intensities up to 120 dB HL and detection of residual hearing in patients with severe-to-profound hearing loss. Aim to compare ASSR thresholds and behavioral test results in children with suspected severe-to-profound hearing loss. Methods Cross sectional study to compare ASSR and behavioral responses (VRA or audiometry) in 63 pediatric cochlear implant candidates (126 ears) aged between 6 and 72 months. We included children with normal otomicroscopy, absent responses to click-ABR and otoaccoustic emissions. We excluded children with inner ear malformations, auditory neuropathy spectrum disorder or who did not complete VRA or achieve EEG noise < 30 nV during the ASSR test. Air-conduction ASSR stimuli were continuous sinusoidal tones presented at 0.5, 1, 2 and 4 kHz starting at 110 dB HL. Behavioral thresholds were acquired with warble tones presented at 0.5, 1, 2 and 4 kHz in each ear through insert or head phones at maximum presentation level of 120 dB HL. Results Behavioral thresholds were obtained in 36.7% (185/504) of all frequencies in all subjects, 9% in intensities >110 dB HL. Among 504 ASSR measurements, 53 thresholds were obtained (10.5%). Overall 89.5% of the tested frequencies did not show any response at 110 dB HL. Most responses were at 500 Hz. Mean differences between behavioral and ASSR thresholds varied from 0.09 to 8.94 dB. Twenty-seven comparisons of behavioral and ASSR thresholds were obtained: 12 at 0.5 kHz, 9 at 1 kHz, 5 at 2 kHz and 1 at 4 kHz. Absent responses were observed in both tests in 38.1% at 0.5 kHz, 52.4% at 1 kHz, 74.6% at 2 kHz and 81.0% at 4 kHz. Specificity was > 90% at 1, 2 and 4 kHz. In ears with no behavioral response at 120 dB HL all ASSR thresholds were in the profound hearing loss range, 90% of them were ≥110 dB HL. Conclusion Among 63 pediatric CI candidates, absent responses to high-intensity ASSR was the major finding (specificity > 90%) predicting behavioral thresholds in the profound hearing loss range. These findings can be helpful to confirm the decision for cochlear implantation. [ABSTRACT FROM AUTHOR]

Conclusion: The correlations between behavioral and auditory steady-state response (ASSR) thresholds were significant at 500, 1000, 2000, and 4000 Hz. ASSR presented high sensitivity and specificity in the detection of residual hearing in cochlear implant candidates when compared with warble-tone audiometry. Objectives: To assess residual hearing in cochlear implant candidates by comparing the electrophysiological thresholds obtained in dichotic single-frequency ASSR with behavioral thresholds at 500, 1000, 2000, and 4000 Hz. Methods: This was a comparative study between ASSR and warble-tone audiometry thresholds in 40 cochlear implant candidates (80 ears) before cochlear implantation with bilateral severe-to-profound sensorineural hearing loss. Results: Thresholds were obtained in 62.5% of all frequencies evaluated in warble-tone audiometry and in 63.1% in the ASSR. ASSR sensitivity was 96% and specificity was 91.6%. Mean differences between behavioral and ASSR thresholds did not reach significance at any frequencies. Strong correlations between behavioral and ASSR thresholds were observed in 500, 1000, and 2000 Hz and moderate in 4000 Hz, with correlation coefficients varying from 0.65 to 0.81. On 90% of occasions, ASSR thresholds were acquired within 10 dB of behavioral thresholds. [ABSTRACT FROM AUTHOR]

In order to examine auditory thresholds and hearing sensitivity during aging in the gray mouse lemur ( Microcebus murinus), suggested to represent a model for early primate evolution and Alzheimer research, we applied brainstem-evoked response audiometry (BERA), traditionally used for screening hearing sensitivity in human babies. To assess the effect of age, we determined auditory thresholds in two age groups of adult mouse lemurs (young adults, 1-5 years; old adults, ≥7 years) using clicks and tone pips. Auditory thresholds indicated frequency sensitivity from 800 Hz to almost 50 kHz, covering the species tonal communication range with fundamentals from about 8 to 40 kHz. The frequency of best hearing at 7.9 kHz was slightly lower than that and coincided with the dominant frequencies of communication signals of a predator. Aging shifted auditory thresholds in the range between 2 and 50.4 kHz significantly by 12-27 dB. This mild presbyacusis, expressed in a drop of amplitudes of BERA signals, but not discernible in latencies of responses, suggests a metabolic age-related decrease potentially combined with an accompanying degeneration of the cochlear nerve. Our findings on hearing range of this species support the hypothesis that predation was a driving factor for the evolution of hearing in small ancestral primates. Likewise, results provide the empirical basis for future approaches trying to differentiate peripheral from central factors when studying Alzheimer's disease-like pathologies in the aging brain. [ABSTRACT FROM AUTHOR]

Non-mammalian vertebrates rely on electrical resonance for frequency tuning in auditory hair cells. A key component of the resonance exhibited by these cells is an outward calcium-activated potassium current that flows through large-conductance calcium-activated potassium (BK) channels. Previous work in midshipman fish (Porichthys notatus) has shown that BK expression correlates with seasonal changes in hearing sensitivity and that pharmacologically blocking these channels replicates the natural decreases in sensitivity during the winter non-reproductive season. To test the hypothesis that reducing BK channel function is sufficient to change auditory thresholds in fish, morpholino oligonucleotides (MOs) were used in larval zebrafish (Danio rerio) to alter expression of slola and slolb, duplicate genes coding for the pore-forming a-subunits of BK channels. Following MO injection, microphonic potentials were recorded from the inner ear of larvae. Quantitative real-time PCR was then used to determine the MO effect on slola and slolb expression in these same fish. Knockdown of either slola or slolb resulted in disrupted gene expression and increased auditory thresholds across the same range of frequencies of natural auditory plasticity observed in midshipman. We conclude that interference with the normal expression of individual slol genes is sufficient to increase auditory thresholds in zebrafish larvae and that changes in BK channel expression are a direct mechanism for regulation of peripheral hearing sensitivity among fishes. [ABSTRACT FROM AUTHOR]

The efficiency of acoustic communication depends on the power generated by the sound source, the attributes of the environment across which signals propagate, the environmental noise and the sensitivity of the intended receivers. Eupsophus emiliopugini, an anuran from the temperate austral forest communicates by means of an advertisement call of moderate intensity within the range for anurans. To estimate the range over which these frogs communicate effectively, we conducted measurements of call sound levels and of auditory thresholds to pure tones and to synthetic conspecific calls. The results show that E. emiliopugini produces advertisement calls of about 84 dB SPL at 0.25 m from the caller. The signals are affected by attenuation as they propagate, reaching average values of about 47 dB SPL at 8 m from the sound source. Midbrain multi-unit recordings show quite sensitive audiograms within the anuran range, with thresholds of about 44 dB SPL for synthetic imitations of conspecific calls, which would allow communication at distances beyond 8 m. This is an extended range as compared to E. calcaratus, a related syntopic species for which a previous study has shown to be restricted to active acoustic spaces shorter than 2 m. The comparison reveals divergent strategies for related taxa communicating amid the same environment. [ABSTRACT FROM AUTHOR]

Background: The relationship between smoking and hearing loss has been debated. Smoking appears to have an effect on auditory acuity and the proposed mechanisms are the direct oxidative damage on cochlea caused by toxic substances inhaled with the cigarette smoke or to the acceleration of the atherosclerotic process in the cochlear artery. Objectives: To record the auditory thresholds of age matched male smokers and non-smokers of age group 20-40 yrs, using pure tone audiometer and compare the auditory thresholds between the groups. Method: Age matched male 100 smokers and 100 non-smokers were subjected to pure tone audiometric assessment. The smoking history in terms of pack-years was also noted. The data was statistically analyzed. Results: Smokers group were significantly hearing impaired than the non-smokers group. The hearing impairment was noted at all frequencies tested. Higher frequencies were more affected than the lower frequencies. The auditory thresholds of smokers had significant positive correlation with smoking history, indicating that auditory thresholds rise as the number of pack-years increase. Conclusion: Smoking causes hearing impairment. The higher frequencies are more affected. The auditory thresholds rise as the number of pack-years increase. [ABSTRACT FROM AUTHOR]

The efficiency of acoustic communication depends on the power generated by the sound source, the quality of the environment across which signals propagate, the environmental noise and the sensitivity of the intended receivers. Eupsophus calcaratus, an anuran from the temperate austral forest, communicates by means of an advertisement call of weak intensity in a sound-attenuating environment. To estimate the range over which these frogs communicate effectively, we conducted measurements of sound level and degradation patterns of propagating advertisement calls in the field, and measurements of auditory thresholds to pure tones and to natural calls in laboratory conditions. The results show that E. calcaratus produces weak advertisement calls of about 72 dB sound pressure level (SPL) at 0.25 m from the caller. The signals are affected by attenuation and degradation patterns as they propagate in their native environment, reaching average values of 61 and 51 dB SPL at 1 and 2 m from the sound source, respectively. Midbrain multi-unit recordings show a relatively low auditory sensitivity, with thresholds of about 58 dB SPL for conspecific calls, which are likely to restrict communication to distances shorter than 2 m, a remarkably short range as compared to other anurans. [ABSTRACT FROM AUTHOR]

Abstract: Background: Depression has been related to sensory modulation and notably to auditory modifications such as alterations in auditory event-related potentials, abnormal patterns of auditory habituation, increased activation of primary and secondary auditory cortex, and higher bilateral auditory thresholds. However, few experiments have considered the exploration of the auditory system in depression. The aim of the experiment is to further explore auditory thresholds across a higher number of frequencies than has previously been undertaken in depressed subjects, to determine whether thresholds are modified as compared to controls, and if so, at which frequencies. Methods: 25 pure-tones covering a large range of frequencies from 125Hz to 8kHz were used to measure both air and bone conduction (AC and BC respectively) hearing thresholds. 13 patients with depression and post-traumatic disorder matched for age, sex and education level with 13 healthy subjects, were tested. Results: Hearing thresholds were found to be significantly poorer in depressed participants than in controls for frequencies from 2.75Hz to 8kHz in BC, and for 0.5, 0.75, 0.875 and 2.0–8.0kHz pure-tone frequencies in AC. Limitations: Given that the depressed patients also had comorbid post-traumatic disorder, it should be verified whether their modified pure-tone audiometry is only related to depression. Conclusions: The AC and BC pure-tone auditory threshold measurement may provide new and different insights into the aetiology and evolution of depression. [Copyright &y& Elsevier]

The auditory system of noctuoid moths capable to respond to ultrasounds has long been a model for anti-predator studies in neuroethology. Many moths avoid hunting bats by listening for their echolocation calls and taking evasive manoeuvres to escape predation. Besides these flight defences, certain tiger moths (Arctiidae) emit high-frequency clicks to jam the echolocator of an attacking bat. Another suggested function for ultrasonic audition in moths along with their capability to emit loud ultrasonic clicks was pulse echolocation. However, it seemed difficult to arrange sufficient temporal resolution in a simple invertebrate auditory system. Here we present an evidence of moth's capability to perceive an echo following its own click with a very short delay. The behavioral responses of moths to the acoustic pulses imitating echoes of their own clicks were investigated under conditions of tethered flight. It has been found that such echo-like stimulation evokes an increase in average emission rate of own acoustic signals in moths. Auditory thresholds were measured in two noctuid species (Enargia paleacea Esp. and Blepharita satura Schiff.) at stimulus delays 0.2, 0.3, 0.5 and 1 ms in relation to the respective moth clicks. Our findings reveal the ability of these moths to perceive echoes of their own signals, thus demonstrating potential possibility for use of pulse echolocation. [ABSTRACT FROM AUTHOR]

In this study we investigated the effects of amalgam dental fillings on auditory thresholds. Participants (n=39) were non-smoking women age 40 to 45. Regression and correlation analyses were performed between auditory thresholds, measured from 0.25 to 16 kHz, and the number/surface area of dental fillings, using the ASHA criteria for ototoxic change as a reference for comparison. No significant correlation (p>0.05) was found between composite (non-amalgam) filling or drilling data and auditory thresholds. However, there was a significant positive linear correlation between amalgam filling data and auditory thresholds at 8, 11.2, 12.5, 14, and 16 kHz. The strongest association (r=0.587, n=39, p<.001, r2=0.345) was at 14 kHz, where each additional amalgam filling was associated with a 2.4 dB decline in hearing threshold (95% confidence interval [CI], 1.3-3.5 dB). The results suggest an association between more amalgam fillings and poorer thresholds at higher frequencies, which could contribute to presbyacusis in developed countries. This provides further argument for the use of amalgams to be phased out where suitable alternatives exist. [ABSTRACT FROM AUTHOR]

Recently, the non-invasive auditory brainstem response (ABR) technique has been applied to the determination of hearing sensitivity in fish. The technique has some advantages over, and methodological differences from, the classical techniques. The auditory thresholds of common carp were measured by the ABR technique. The classical method was applied to measure cardiac response by electrocardiogram (ECG) after conditioning with electric shock. The most sensitive frequency obtained by ABR was 505 Hz, and by ECG, 1000 Hz. The shapes of the audiogram obtained by ABR and ECG were similar, though threshold levels in both audiograms differed from each other. Furthermore, audiograms obtained by using behavioral techniques were compared with those taken by the ABR and ECG techniques to assess the validity of the ABR technique for testing fish hearing sensitivity. The measured threshold levels increased in the order of behavioral, ABR, and ECG techniques, in the range below 1000 Hz. [ABSTRACT FROM AUTHOR]

Baboons were trained in both auditory and visual reaction time procedures to release a response lever in the presence of low-intensity stimuli. By varying the stimulus intensity from trial to trial, functions relating reaction time (elapsed time from stimulus onset to lever release) to stimulus intensity were established, and detection thresholds were measured. The effects of acute, IM injections of d-methamphetamine (0.001-1.0 mg/kg) were examined on these psychophysical performance baselines. Reaction times for acoustic stimuli generally were faster for higher drug doses, whereas reaction times for visual stimuli either lengthened or shortened, depending on both drug dose and individual differences among animals. Auditory thresholds were unaffected at all drug doses studied, whereas visual thresholds were generally elevated at doses of 0.1 mg/kg and above. [ABSTRACT FROM AUTHOR]

Absolute auditory thresholds of six adult lesser spear-nosed bats Phyllostomus discolor (Chiroptera, Phyllostomidae) were determined in a two-alternative forced-choice procedure. Behavioral responses to pure tone stimuli could be elicited throughout the tested frequency range of 5-142 kHz. The shape of the average audiogram is characterized by two sensitivity peaks and a pronounced increase of thresholds around 55 kHz, and towards the limits of the tested frequency range. The spectral extent of both sensitivity peaks shows a close relation to the bandwidth of two types of species-specific vocalizations. The first low threshold area (> 10 and < 55 kHz) of the audiogram seems perfectly adapted to the directive call used for intraspecific communication, whereas the second sensitivity peak, centered around 85 kHz, covers most of the bandwidth of the species' echolocation calls. [ABSTRACT FROM AUTHOR]

Auditory brainstem responses (ABRs) were characterized at 37 °C in ground squirrels ( Citellus lateralis) which were implanted with recording screws to record ABRs, and a thermistor to record brain temperature. After two weeks ground squirrels were reanesthetized and tone pips and clicks were delivered through a TDH-49 headphone. Recorded ABRs were found to vary in a predictable manner as a function of stimulus frequency and intensity. At intensities above 50 dB SPL, ABRs could be recorded over the range tested (2-32 kHz). An 8 kHz tone pip was the best frequency for recording ABRs at the lowest stimulus intensities. Latencies decreased as stimulus frequencies increased from 4 kHz to 32 kHz. [ABSTRACT FROM AUTHOR]