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With his work on the Fogg Art Museum and Boston Symphony Hall between 1895 and 1900, Wallace C. Sabine laid a foundation for the field of architectural acoustics as a science. Prior to that, architects employed various quantifiable notions in acoustic design. Previous studies have reviewed metric guidelines based on the directivity of the human voice, which was utilized in at least 11 rooms in pre-Sabine times. Others studies have reviewed pre-Sabine design guidelines that were based on the quantification of the perception threshold between direct sound and first order reflections and which were followed in several rooms with acoustical performance needs. As the first studies concerned the direct sound and the second set concerned first order reflections, this study reviews opinions and knowledge regarding the later part of the acoustic response, also known as reverberation, during the 19th century. This effort brings to light a room acoustic design evolution showing why concert halls at the end of the 19th century mainly had surface finishes of wood and plaster as well as limited ceiling heights. While not equal to Sabine's thoroughness and completeness, numerous early experimental and theoretical reverberation approaches were found to hint at similar notions with both qualitative and quantitative efforts.

Dynamic directivity is a specific characteristic of the human voice, showing time-dependent variations while speaking or singing. To study and model the human voice's articulation-dependencies and provide datasets that can be applied in virtual acoustic environments, full-spherical voice directivity measurements were carried out for 13 persons while articulating eight phonemes. Since it is nearly impossible for subjects to repeat exactly the same articulation numerous times, the sound radiation was captured simultaneously using a surrounding spherical microphone array with 32 microphones and then subsequently spatially upsampled to a dense sampling grid. Based on these dense directivity patterns, the spherical voice directivity was studied for different phonemes, and phoneme-dependent variations were analyzed. The differences between the phonemes can, to some extent, be explained by articulation-dependent properties, e.g., the mouth opening size. The directivity index, averaged across all subjects, varied by a maximum of 3 dB between any of the vowels or fricatives, and statistical analysis showed that these phoneme-dependent differences are significant.

The human voice is a complex acoustic signal that conveys talker identity via individual differences in numerous features, including vocal source acoustics, vocal tract resonances, and dynamic articulations during speech. It remains poorly understood how differences in these features contribute to perceptual dissimilarity of voices and, moreover, whether linguistic differences between listeners and talkers interact during perceptual judgments of voices. Here, native English- and Mandarin-speaking listeners rated the perceptual dissimilarity of voices speaking English or Mandarin from either forward or time-reversed speech. The language spoken by talkers, but not listeners, principally influenced perceptual judgments of voices. Perceptual dissimilarity judgments of voices were always highly correlated between listener groups and forward/time-reversed speech. Representational similarity analyses that explored how acoustic features (fundamental frequency mean and variation, jitter, harmonics-to-noise ratio, speech rate, and formant dispersion) contributed to listeners' perceptual dissimilarity judgments, including how talker- and listener-language affected these relationships, found the largest effects relating to voice pitch. Overall, these data suggest that, while linguistic factors may influence perceptual judgments of voices, the magnitude of such effects tends to be very small. Perceptual judgments of voices by listeners of different native language backgrounds tend to be more alike than different.

With the work of Wallace C. Sabine on the lecture hall of the Fogg Art Museum and concert hall of Boston Symphony Hall, a foundation for the field of architectural acoustics as a science was laid between 1895 and 1900. Prior to that, architects employed various notions in acoustic design. Previous studies by the authors have reviewed 18th and 19th century design guidelines that were based on the quantification of the perception threshold between direct sound and first order reflections, with these guidelines being followed in the design of several rooms with acoustical demands. This study reviews an alternate metric guideline, based on the directivity and propagation distance of the human voice, which was utilized in several halls also during the 18th and 19th centuries. The related acoustic experiments tested how far sound was perceivable towards the front, sides, and rear of a speaking person. These ratios were used in the acoustical design of at least five lecture halls, four theater halls, one opera hall, and one concert hall, constructed in Germany, England, and the USA. These historic designs, and comparisons to modern measures and guidelines, are reviewed.

In voice communication in windy outdoor conditions, complex velocity gradients appear in the flow field around the source, the receiver, and also in the atmosphere. It is commonly known that voice emanates stronger towards the downstream direction when compared with the upstream direction. In literature, the atmospheric effects are used to explain the stronger emanation in the downstream direction. This work shows that the wind also has an effect to the directivity of voice also favouring the downstream direction. The effect is addressed by measurements and simulations. Laboratory measurements are conducted by using a large pendulum with a loudspeaker mimicking the human head, whereas practical measurements utilizing the human voice are realized by placing a subject through the roof window of a moving car. The measurements and a simulation indicate congruent results in the speech frequency range: When the source faces the downstream direction, stronger radiation coinciding with the wind direction is observed,and when it faces the upstream direction, radiation is not affected notably. The simulated flow gradients show a wake region in the downstream direction, and the simulated acoustic field in the flow show that the region causes a wave-guide effect focusing the sound in the direction.

Musical instruments are considered natural sound sources with specific directivities. Each instrument unique directivity needs to be identified and implemented in auralization of sound in room acoustic designs. This paper shows detailed directivity measurements on selected musical instruments, human voice, and impulse sources used in room acoustics design under realistic conditions. This work presents results that are measured using acoustic beamforming techniques. Measurements are based on simultaneous recording using a hemispherical array of 120 microphones. The directivity data are measured and analyzed in the time, and frequency domain, and effects in the near field of musical instruments are explored. Dynamic variations in the musical instruments’ directivity relative to sound power, loudness (intensity, pressure), projection, and the apparent size of the sound or volume are presented. Recorded data are presented in static or dynamic mode as well as in both 2- and 3-dimensional format using the beamforming software as well as Math lab algorithm. The results of this work are applicable toward improvement in the quality of auralization of musical instrument in simulation tools and vocal production studies and room acoustic sound filed. Evaluation of their projected radiations’ pattern contributes to a more realistic acoustic design simulations or virtual reality applications.Musical instruments are considered natural sound sources with specific directivities. Each instrument unique directivity needs to be identified and implemented in auralization of sound in room acoustic designs. This paper shows detailed directivity measurements on selected musical instruments, human voice, and impulse sources used in room acoustics design under realistic conditions. This work presents results that are measured using acoustic beamforming techniques. Measurements are based on simultaneous recording using a hemispherical array of 120 microphones. The directivity data are measured and analyzed in the time, and frequency domain, and effects in the near field of musical instruments are explored. Dynamic variations in the musical instruments’ directivity relative to sound power, loudness (intensity, pressure), projection, and the apparent size of the sound or volume are presented. Recorded data are presented in static or dynamic mode as well as in both 2- and 3-dimensional format using the beamf...

In modern public architecture, a large amount of glass is often used as the material, and the space is visually connected by its transparency. However, on the other hand, the soundscape is divided. In the project of “Chino Cultural Complex,” we intended to connect the two spaces through sound. This consists of a sound tube running approximately 20 m through underground of the courtyard. By speaking into one end of the tube, participants can converse with counterparts only faintly visible on the other side, with the voice as clear as if they were close to the ear. In this paper, we show the basic experiment of the sound tube in the anechoic chamber. We found an appropriate diameter of the tube in which the human voice was easy propagating on each other. Then, sound tube is covered with the absorbing materials and is set by the anti-vibrating suspension in the box culvert on site. The anti-vibration structure protected transmission of the structure-bone sound except voices to the sound tube. In other projects, we have designed this sound tube to listen to sound of waves, wind, and footsteps. We hope that these activities will provide significant soundscape design.In modern public architecture, a large amount of glass is often used as the material, and the space is visually connected by its transparency. However, on the other hand, the soundscape is divided. In the project of “Chino Cultural Complex,” we intended to connect the two spaces through sound. This consists of a sound tube running approximately 20 m through underground of the courtyard. By speaking into one end of the tube, participants can converse with counterparts only faintly visible on the other side, with the voice as clear as if they were close to the ear. In this paper, we show the basic experiment of the sound tube in the anechoic chamber. We found an appropriate diameter of the tube in which the human voice was easy propagating on each other. Then, sound tube is covered with the absorbing materials and is set by the anti-vibrating suspension in the box culvert on site. The anti-vibration structure protected transmission of the structure-bone sound except voices to the sound tube. In other projec...

The human voice signal originates from the vibrations of the two vocal folds within the larynx. The interactions of several intrinsic laryngeal muscles adduct and shape the vocal folds to facilitate vibration in response to airflow. Three-dimensional vocal fold dynamics are extracted from in vitro hemilarynx experiments and fitted by a numerical three-dimensional-multi-mass-model (3DM) using an optimization procedure. In this work, the 3DM dynamics are optimized over 24 experimental data sets to estimate biomechanical vocal fold properties during phonation. Accuracy of the optimization is verified by low normalized error (0.13 ± 0.02), high correlation (83% ± 2%), and reproducible subglottal pressure values. The optimized, 3DM parameters yielded biomechanical variations in tissue properties along the vocal fold surface, including variations in both the local mass and stiffness of vocal folds. That is, both mass and stiffness increased along the superior-to-inferior direction. These variations were statistically analyzed under different experimental conditions (e.g., an increase in tension as a function of vocal fold elongation and an increase in stiffness and a decrease in mass as a function of glottal airflow). The study showed that physiologically relevant vocal fold tissue properties, which cannot be directly measured during in vivo human phonation, can be captured using this 3D-modeling technique.

Although the amount of inharmonic energy (noise) present in a human voice is an important determinant of vocal quality, little is known about the perceptual interaction between harmonic and inharmonic aspects of the voice source. This paper reports three experiments investigating this issue. Results indicate that perception of the harmonic slope and of noise levels are both influenced by complex interactions between the spectral shape and relative levels of harmonic and noise energy in the voice source. Just-noticeable differences (JNDs) for the noise-to-harmonics ratio (NHR) varied significantly with the NHR and harmonic spectral slope, but NHR had no effect on JNDs for NHR when harmonic slopes were steepest, and harmonic slope had no effect when NHRs were highest. Perception of changes in the harmonic source slope depended on NHR and on the harmonic source slope: JNDs increased when spectra rolled off steeply, with this effect in turn depending on NHR. Finally, all effects were modulated by the shape of the noise spectrum. It thus appears that, beyond masking, understanding perception of individual parameters requires knowledge of the acoustic context in which they function, consistent with the view that voices are integral patterns that resist decomposition.

According to recent model investigations, vocal tract resonance is relevant to vocal registers. However, no experimental corroboration of this claim has been published so far. In the present investigation, ten professional tenors' vocal tract configurations were analyzed using MRI volumetry. All subjects produced a sustained tone on the pitch F4 (349 Hz) on the vowel /a/ (1) in modal and (2) in falsetto register. The area functions were estimated from the MRI data and their associated formant frequencies were calculated. In a second condition the same subjects repeated the same tasks in a sound treated room and their formant frequencies were estimated by means of inverse filtering. In both recordings similar formant frequencies were observed. Vocal tract shapes differed between modal and falsetto register. In modal as compared to falsetto the lip opening and the oral cavity were wider and the first formant frequency was higher. In this sense the presented results are in agreement with the claim that the formant frequencies differ between registers.

Peoples communicates with others using voice that is essayist way. Voice is a means of conveying your opinions or thoughts. In complex social life, voices become rough and tone changes due to various causes such as condition, stress, singing, effect of drugs and changing the pitch due to changes in the numerical value of hormones. This will result in the other party not being able to communicate. In order to solve this treatment from the hospital. In this paper, we introduce the phenomenon of improving the clarity of human voice by utilizing the reflected sound waves of the palm. In previous research, We proposed the methods that using voice recorded or a solid surface mug. In this study, we propose method that peoples own voice reflected from the palm of their vocal organ. Speak the voice for “ah,” “e,” “o”, “ooo” for a minute and make a sound wave in each mouth and massage it. The reflected voice from the palm stimulates delicate massage of the skin cells of the mouth, further enhancing the original voice enhancement function.

We investigated how emotional sounds are processed by musicians and non-musicians. Expertise through musical training can shape the way emotional music is processed. However, emotional sounds can arise from other sound sources, too, such as vocal expressions like laughter or cries. Musical expertise can also influence the way these emotional sounds are processed, thus, the impact of musical expertise can generalize over a wide range of emotional sounds. A recent study investigated oscillatory brain activity related to the processing of emotional sounds in musicians and non-musicians (Nolden, Rigoulot, Jolicoeur, & Armony, 2017, see also Rigoulot, Pell, & Armony, 2015). Musicians showed greater overall oscillatory brain activity than non-musicians. This was true for emotional music as well as for emotional sounds produced by the human voice, suggesting that expertise in processing one domain generalizes to different domains. We investigated how emotional sounds are processed by musicians and non-musicians. Expertise through musical training can shape the way emotional music is processed. However, emotional sounds can arise from other sound sources, too, such as vocal expressions like laughter or cries. Musical expertise can also influence the way these emotional sounds are processed, thus, the impact of musical expertise can generalize over a wide range of emotional sounds. A recent study investigated oscillatory brain activity related to the processing of emotional sounds in musicians and non-musicians (Nolden, Rigoulot, Jolicoeur, & Armony, 2017, see also Rigoulot, Pell, & Armony, 2015). Musicians showed greater overall oscillatory brain activity than non-musicians. This was true for emotional music as well as for emotional sounds produced by the human voice, suggesting that expertise in processing one domain generalizes to different domains.

Timbre encompasses every distinguishing quality of a sound other than its pitch, duration, loudness, and sound location. Musical sound makers exploit contrasts in timbre. The voice organ in particular is capable of an impressive array of vibrational patterns with acoustic consequences perceived as timbral changes. As a first step towards determining the dimensionality of perceptual timbre in a singing human voice, we assessed the relation between, on the one hand, production parameters, executed by a well-trained vocalist capable of the articulation control necessary for demonstrations, and on the other hand, the complex spectral and temporal modulations in the acoustic signal of the resulting 50 timbral variants. Production parameters on a high front vowel included 5 laryngeal heights (from the lowest possible to a mostly elevated position), 4 modes of phonation (clean, blowy, breathy, and pressed), and several changes to resonance (nasal, bright, and muted) as well as vocal register differences comparin...

Paralinguistic features of speech communicate emotion in the human voice. In addition to semantic content, speakers imbue their messages with prosodic features comprised of acoustic variations that listeners decode to extract meaning. Psychological science refers to these acoustic variations as affective prosody. Most studies of affective prosody obscure semantic content, although the resulting stimuli are less representative of naturally occurring emotional speech. The presented works details the creation of a naturalistic emotional speech database on which both acoustical analysis and a listening study were conducted. To this end, 55 adults were recorded speaking the same semantic content in happy, angry, and sad voices. Based on prior acoustic analyses of affective prosody, classic parameters were extracted including pitch, loudness, timing, as well as other low-level descriptors, and compared the acoustic features of each emotion with published evidence and theory. Preliminary results indicate that this naturalistic speech samples yielded acoustic features that are congruent with prior experimental stimuli of anger and happiness, but was less consistent with sadness. The results of the listening study indicated that listeners discriminated the intended emotions with 92% accuracy. The dataset therefore yielded a database of emotionally salient acoustical information for further analyses. [Work supported by NIH-R21-104547.]

The factors contributing to human voice production are not yet fully understood. Even normal human phonation with a symmetric glottal opening area is still the subject of extensive investigation. Among others, it has already been shown that fluid dynamics has a strong influence on the vocal process. The full characterization of the glottal jet has not been accomplished yet. Time-resolved measurement and visualization of the three-dimensional (3D) flow downstream the human vocal folds are difficult if not impossible to perform in vivo. Therefore, it is common to use mechanical and numerical models with a simplified shape and motion profile of the vocal folds. In this article, further results regarding the 3D flow structure obtained in a 3:1 up-scaled dynamic glottis model (cam model) in a water circuit are given, extending earlier work [M. Triep et al. (2005). Exp. Fluids 39, 232-245]. The model mimics the temporal variation in the 3D contour of the glottal gap while water flow reduces the characteristic frequencies by the order of 1/140. The unsteady flow processes downstream of the vocal folds are visualized in slow motion and analyzed in detail via particle imaging techniques. The visualization results show complex 3D flow behavior of lengthwise jet contraction and axis switching. In addition, the time-dependent flow rate during the phonatory oscillation cycle is measured in detail. It is shown that the pressure loss is decreased in the presence of a second constriction downstream of the glottis in form of ventricular folds and it is observed that for this case the jet is stabilized in the divergent phase of the cycle.

For the investigation of the physical processes of human phonation, inhomogeneous synthetic vocal folds were developed to represent the full fluid-structure-acoustic coupling. They consisted of polyurethane rubber with a stiffness in the range of human vocal folds and were mounted in a channel, shaped like the vocal tract in the supraglottal region. This test facility permitted extensive observations of flow-induced vocal fold vibrations, the periodic flow field, and the acoustic signals in the far field of the channel. Detailed measurements were performed applying particle-image velocimetry, a laser-scanning vibrometer, a microphone, unsteady pressure sensors, and a hot-wire probe, with the aim of identifying the physical mechanisms in human phonation. The results support the existence of the Coanda effect during phonation, with the flow attaching to one vocal fold and separating from the other. This behavior is not linked to one vocal fold and changes stochastically from cycle to cycle. The oscillating flow field generates a tonal sound. The broadband noise is presumed to be caused by the interaction of the asymmetric flow with the downstream-facing surfaces of the vocal folds, analogous to trailing-edge noise.

This study investigates four qualities of singing voice in a classically trained baritone: "naive falsetto," "countertenor falsetto," "lyrical chest" and "full chest." Laryngeal configuration and vocal fold behavior in these qualities were studied using laryngeal videostroboscopy, videokymography, electroglottography, and sound spectrography. The data suggest that the four voice qualities were produced by independently manipulating mainly two laryngeal parameters: (1) the adduction of the arytenoid cartilages and (2) the thickening of the vocal folds. An independent control of the posterior adductory muscles versus the vocalis muscle is considered to be the physiological basis for achieving these singing voice qualities.

Accurate measurement of the softest sound levels of phonation presents technical and methodological challenges. This study aimed at (1) reliably obtaining normative data on sustained softest sound levels for the vowel [a:] at comfortable pitch; (2) comparing the results for different frequency and time weighting methods; and (3) refining the Union of European Phoniatricians' recommendation on allowed background noise levels for scientific and equipment manufacturers' purposes. Eighty healthy untrained participants (40 females, 40 males) were investigated in quiet rooms using a head-mounted microphone and a sound level meter at 30 cm distance. The one-second-equivalent sound levels were more stable and more representative for evaluating the softest sustained phonations than the fast-time-weighted levels. At 30 cm, these levels were in the range of 48-61 dB(C)/41-53 dB(A) for females and 49 - 64 dB(C)/35-53 dB(A) for males (5% to 95% quantile range). These ranges may serve as reference data in evaluating vocal normality. In order to reach a signal-to-noise ratio of at least 10 dB for more than 95% of the normal population, the background noise should be below 25 dB(A) and 38 dB(C), respectively, for the softest phonation measurements at 30 cm distance. For the A-weighting, this is 15 dB lower than the previously recommended value.

We provide a direct demonstration that nonhuman primates spontaneously perceive changes in formant frequencies in their own species-typical vocalizations, without training or reinforcement. Formants are vocal tract resonances leading to distinctive spectral prominences in the vocal signal, and provide the acoustic determinant of many key phonetic distinctions in human languages. We developed algorithms for manipulating formants in rhesus macaque calls. Using the resulting computer-manipulated calls in a habituation/dishabituation paradigm, with blind video scoring, we show that rhesus macaques spontaneously respond to a change in formant frequencies within the normal macaque vocal range. Lack of dishabituation to a "synthetic replica" signal demonstrates that dishabituation was not due to an artificial quality of synthetic calls, but to the formant shift itself. These results indicate that formant perception, a significant component of human voice and speech perception, is a perceptual ability shared with other primates.

The study investigated the segmental intelligibility of four currently available text-to-speech (TTS) products under 0-dB and 5-dB signal-to-noise ratios. The products were IBM ViaVoice™ version 5.1, which uses formant coding, Festival version 1.4.2, a diphone-based LPC TTS product, AT&T Next-Gen™, a half-phone-based TTS product that uses harmonic-plus-noise method for synthesis, and FlexVoice™2, a hybrid TTS product that combines concatenative and formant coding techniques. Overall, concatenative techniques were more intelligible than formant or hybrid techniques, with formant coding slightly better at modeling vowels and concatenative techniques marginally better at synthesizing consonants. No TTS product was better at resisting noise interference than others, although all were more intelligible at 5 dB than at 0-dB SNR. The better TTS products in this study were, on the average, 22% less intelligible and had about 3 times more phoneme errors than human voice under comparable listening conditions. The hybrid TTS technology of FlexVoice had the lowest intelligibility and highest error rates. There were discernible patterns of errors for stops, fricatives, and nasals. Unrestricted TTS output—e-mail messages, news reports, and so on—under high noise conditions prevalent in automobiles, airports, etc. will likely challenge the listeners.

Emotions can be conveyed through a variety of channels in the auditory domain such as the human voice or music. Recent studies suggest that expertise in one sound category can impact the processing of emotional sounds in other sound categories. We focused here on how the neural processing of emotional information varies as a function of sound category and expertise of participants. Electroencephalogram (EEG) of 20 non-musicians and 17 musicians was recorded while they listened to speech prosody, vocalizations (such as screams and laughter), and musical sounds. The amplitude of EEG-oscillatory activity in the theta, alpha, beta, and gamma band was quantified and Independent Component Analysis (ICA) was used to identify underlying components of brain activity in each band. Sound category-dependent activations were found in frontal theta and alpha, as well as greater activation for musicians than for non-musicians. Differences in the beta band were mainly due to differential processing of speech. The results...

Skillful players of brass instruments and reed woodwinds are able to control the vocal tract effectively and perform with intended pitches and sound qualities. The player’s vocal tract is, to a first approximation, connected with the instrument bore acoustically in series. If the magnitude of the vocal tract impedance is comparable with the bore impedance, the acoustic pressure in the mouth can then exert influences with a vibrating reed. However, studies reliant enough to confirm the configuration of the vocal tract while playing are limited. In this study, a magnetic resonance imaging (MRI) device was used to scan the vocal tract in three dimensions. The participant was an amateur saxophone player and the instrument was made from reed, mouthpiece, and a short uniform tube. Image data revealed how the vocal tract was formed when she blew a number of different notes. They were also used to determine the cross-sectional area and the input impedance of the vocal tract. The results were compared with trumpet...

Discrimination between normal and pathological voice is a critical component in laryngeal pathology diagnosis and vocal rehabilitative treatment. In the present study, a portable miniature glottal notch accelerometer (GNA) device with supervised machine learning techniques was proposed to discriminate between three human voice types: normal, breathy, and pressed voice. Fourteen native American English speakers who were wearing a GNA device produced five different English single vowels in each of the three voice types. Acoustic features of the GNA signals were extracted using spectral analysis. Preliminary assessments of feature discrepancy among different voice types were made to present physical clues of discrimination. The linear discriminant analysis technique was applied to reduce the dimensionality of the raw-feature vector of the GNA signals. Maximization of between-class distance and minimization of within-class distance were synchronously achieved. The voice types were then classified using several supervised learning techniques, such as Linear Discriminant, Decision Tree, Support Vector Machine, and K-Nearest Neighbors. A classification accuracy of up to 91.0% was achieved. One mapping model from voice input to type output was eventually obtained based on the training set, so as to make predictions with new data in the future work.

The voice of soprano singers reaches at the highest notes among female vocalists. Soprano singers usually have low clarity with respect to pronunciation because their jaw joints and mouth shapes tend to stay rigid in order to maintain high notes for a long time. Five formants found in human voice are differently shaped depending on his or her different physical structures. Especially, high clarity in pronunciation has a distinct formant shape from F1 through F5, because the jaw joint and the mouth shape have a large influence on F4 and F5 appearing in the high frequency range. This paper comparatively analyzes the vocal voices of four different Korean soprano singers concerning clarity in pronunciation. The results of acoustic analysis of these four singers shows that the singer A and the singer D show from F1 ~ up to F3 above 2 kHz but F4 and F5 do not appear in this range, and the singer C had somewhat inconsistency with her formant characteristics as a whole. In the singer B, formants from F1 through F...

When phase relationships between partials of a complex masker produce highly modulated temporal envelopes on the basilar membrane, listeners may detect speech information from temporal dips in the within-channel masker envelopes. This source of masking release (MR) is however located in regions of unresolved masker partials and it is unclear how much of the speech information in these regions is really needed for intelligibility. Also, other sources of MR such as glimpsing in between resolved masker partials may provide sufficient information from regions that disregard phase relationships. This study simplified the problem of speech recognition to a masked detection task. Target bands of speech-shaped noise were restricted to frequency regions containing either only resolved or only unresolved masker partials, as a function of masker phase relationships (sine or random), masker fundamental frequency (F0) (50, 100, or 200 Hz), and masker spectral profile (flat-spectrum or speech-shaped). Although masker phase effects could be observed in unresolved regions at F0s of 50 and 100 Hz, it was only at 50-Hz F0 that detection thresholds were ever lower in unresolved than in resolved regions, suggesting little role of envelope modulations for harmonic complexes with F0s in the human voice range and at moderate level.

Although advances in techniques for image acquisition and analysis have facilitated the direct measurement of three-dimensional vocal tract air space shapes associated with specific speech phonemes, little information is available with regard to changes in three-dimensional (3-D) vocal tract shape as a function of vocal register, pitch, and loudness. In this study, 3-D images of the vocal tract during falsetto and chest register phonations at various pitch and loudness conditions were obtained using electron beam computed tomography (EBCT). Detailed measurements and differences in vocal tract configuration and formant characteristics derived from the eight measured vocal tract shapes are reported.

Alteration of the harmonic structure in voice source spectra, taken over at least two periods of the waveform, may occur due to the presence of fundamental frequency (f0) perturbation, amplitude perturbation, additive noise, or changes within the glottal source signal itself. In order to make accurate inferences regarding glottal-flow dynamics or perceptual evaluations based on spectral measurements taken from the acoustic speech waveform, investigation of the spectral features of each aperiodic component is required. Based on a heuristic development involving a consideration of the partial sum of the Fourier series taken for two periods of a jittered, shimmered, and (additive, random) noise-contaminated signal, the corresponding spectral characteristics are hypothesized. Subsequent to this, the Fourier series coefficients are calculated for the two periods in order to test the hypotheses. Definite spectral differences are found for each aperiodic component; based on these findings differential quantitative spectral measurements are suggested. Further supportive evidence is obtained through use of Fourier transform and periodogram-averaged calculations. The analysis is carried out on synthetically generated glottal-pulse waveforms and on radiated speech waveforms. A discussion of the results is given in terms of voice aperiodicity in general and in terms of their implication for future studies involving human voice signals.

A detailed understanding of the aerodynamics of air flow in the larynx and the vocal tract is needed to refine physiological models of human voice production. This understanding can be applied in speech synthesis, voice diagnostics, and voice recognition. To date, most aeroacoustic models of phonation have been based on Bernoulli's orifice theory, i.e., the assumption that flow phenomena within the larynx are "quasi-steady." This assumption, however, has never been rigorously verified experimentally. In this study, detailed aerodynamic measurements were performed of a pulsating open jet through a modulated orifice with a time-varying area. Orifice geometry and characteristic Reynolds numbers and Strouhal numbers of the pulsating jet flow were representative of speech production. Simple source-filter models based on the quasi-steady flow assumption and an ideal one-dimensional monopole source model were found to yield satisfactory velocity, flow rate, and dynamic pressure predictions for most of the duty cycle. Significant deviations from quasi-steady behavior were observed only during the early part of the duty cycle, where the flow velocity in the center core rapidly reached a peak value immediately after release of the false folds. This acoustic near-field phenomenon did not affect the pressure waves generated by the pulsating jet through the orifice, propagated in the long rigid tube upstream of the orifice. The impact on this phenomenon on actual sound generation within the larynx, and wall pressures on the vocal folds, is not clear.

Human voice production at very high fundamental frequencies is not yet understood in detail. It was hypothesized that these frequencies are produced by turbulences, vocal tract/vocal fold interactions, or vocal fold oscillations without closure. Hitherto it has been impossible to visually analyze the vocal mechanism due to technical limitations. Latest high-speed technology, which captures 20 000 frames/s, using transnasal endoscopy was applied. Up to 1568 Hz human vocal folds do exhibit oscillations with complete closure. Therefore, the recent results suggest that human voice production at very high F0s up to 1568 Hz is not caused by turbulence, but rather by airflow modulation from vocal fold oscillations.

Although vocal fold vibration and the resulting voice production depend on the geometry and mechanical properties of the vocal folds, control of voice is achieved through laryngeal muscle activation, which postures the vocal folds into desired geometry and mechanical properties. Such posturing process is known to cause simultaneous changes in vocal fold position, geometry, stiffness, and tension, which has been hypothesized to be a possible origin of vocal registers. Understanding such co-variations in vocal fold geometry and mechanical properties is thus critical to our understanding of human voice production and control, and the development of muscularly controlled, computationally efficient models of phonation. In this study, an empirical model is developed to link the glottal gap, vocal fold length, vocal fold vertical thickness, and the mechanical properties of the vocal fold to the activation levels of the cricothyroid, thyroarytenoid, lateral cricoarytenoid, interarytenoid, and posterior cricoaryte...

The human voice is one of the easiest methods for the information transmission between human beings. The characteristics of the voice can be varied by different people and different situations, such as utterance speed, pitch tone, vocal organ features, and the gender. Moreover, the voice can be used as a factor for deciding the personal credit rating scores. The reliable parameters of speech signal can be extracted from different characteristics of the spoken information. In this paper, we collected the voices from people who has relatively high personal credit scores, and analyzed them.

In drama theaters, the unamplified human voice is used to convey both information and nuanced emotional cues to large groups of listeners. Supportive sound reflective surfaces are relatively distant from the actors, and the inherent (and desirable) reverberance of a larger space run counter to many accepted practices for achieving speech clarity in smaller spaces. Some theater configurations, such as thrust and in-the-round, are even arranged so that actor faces away from large segments of the audience at any given time, offering further challenges to the connection between actor and audience. This paper will present an understanding of the way that people listen to speech in large rooms, and approaches to room design to support the clarity of unamplified speech. A case study will be presented describing the development of theater design from initial concept through computer modeling and finally with three dimensional measurements and visualizations of the acoustic environment in the completed room.

Synthetic vocal fold replicas are a useful tool for studying human voice production. These replicas are often studied using high-speed imaging, but additional analysis procedures are desired that are lower cost, less data intensive, and more conducive to long-term vibration monitoring. Consequently, this work explores the use of electrical resistance to measure vocal fold contact area across the glottis of a synthetic vocal fold replica. The concept is based on electroglottography (EGG), a clinical tool for measuring vocal fold contact area in vivo. When a small current is passed through the vocal folds, the resistance across the folds varies inversely with the contact area between the folds. This change in resistance thus makes it possible to estimate the degree of glottal closure during vocal fold vibration. For this research, a method of enabling silicone vocal fold replicas to conduct electricity without compromising the sensitive material viscoelastic properties has been developed. The concept will be demonstrated and relationships between contact area and resistance in both static and vibrating (self-oscillating) replicas will be presented.

The study of the physics of human voice production has benefited by the use of synthetic human vocal fold replicas. Extending this concept to avian vocalization, a functioning model of a male mallard syrinx for studying the relationship between syrinx anatomical features and vocalization characteristics is described here. The mallard syrinx is characterized by two sets of labia located at the tracheobronchial juncture, and vocalization is produced by the flow-induced vibration of these labia. Shape and histological composition of labia demonstrate similarities to mammalian vocal folds. In this study, life-sized synthetic replicas based on CT data of an adult male mallard syrinx, including airway and labia regions, are studied. The replicas are fabricated using exceedingly flexible silicone materials that have been previously used in synthetic human vocal fold replicas. The replicas are mounted in tube-like airways representing the trachea and bronchi, with flow generated by an adjustable air supply. In th...

Synthetic vocal fold models have long been used to study features of human voice production that cannot reasonably be studied in vivo. Numerous models have been developed to study different aspects of voice production. Some models have focused, for example, on mimicking geometry or tissue layering while others have been used to study the effect of vibration on live cells. Two aspects of vocal fold structure that have yet to be fully explored are the anisotropic and the inhomogeneous qualities of vocal fold tissue. These features significantly influence vocal fold flow-induced vibratory characteristics. The purpose of this research is to develop and explore models that incorporate anisotropy and inhomogeneity to study their effects on vocal fold vibration. In this presentation, methods and models for studying these features will be discussed; one example is the creation of a fiber matrix via rotary jet spinning that is embedded within silicone vocal fold models to study material anisotropy. Fabrication met...

Over the past few years, Bill Strong has worked with other researchers at Brigham Young University to develop a feasible method to assess high-resolution directivities of played musical instruments and the human voice. The approach has produced numerous directivity balloons with 5-degree angular resolution and variable bandwidths, meeting the requirements of the AES56-2008 standard for loudspeaker measurements. This presentation will give an overview of the method, its validation, and some interesting results for several musical instruments and talkers. Data from the measurements are intended to enhance theoretical and practical efforts of professionals seeking to better understand and work with these live sources of sound.

The speech production system is capable of conveying an abundance of information with regards to sentence text, speaker identity, prosodics, as well as emotion and speaker stress. In an effort to better understand the mechanism of human voice communication, researchers have attempted to determine reliable acoustic indicators of stress using such speech production features as fundamental frequency (F0), intensity, spectral tilt, the distribution of spectral energy, and others. Their findings indicate that more work is necessary to propose a general solution. In this study, we hypothesize that speech consists of a linear and nonlinear component, and that the nonlinear component changes markedly between normal and stressed speech. To quantify the changes between normal and stressed speech, a classification procedure was developed based on the nonlinear Teager Energy operator. The Teager Energy operator provides an indirect means of evaluating the nonlinear component of speech. The system was tested using VC ...

While vocal fold adduction is an important parameter in speech, relatively little has been known on the adjustment of the vocal fold adduction in singing. This study investigates the possibility of separate adjustments of cartilaginous and membranous vocal fold adduction in singing. Six female and seven male subjects, singers and non-singers, were asked to imitate an instructor in producing four phonation types: “aBducted falsetto” (FaB), “aDducted falsetto” (FaD), “aBducted Chest” (CaB), and “aDducted Chest” (CaD). The phonations were evaluated using videostroboscopy, videokymography (VKG), electroglottography (EGG), and audio recordings. All the subjects showed less posterior (cartilaginous) vocal fold adduction in phonation types FaB and CaB than in FaD and CaD, and less membranous vocal fold adduction (smaller closed quotient) in FaB and FaD than in CaB and CaD. The findings indicate that the exercises enabled the singers to separately manipulate (a) cartilaginous adduction and (b) membranous medialization of the glottis though vocal fold bulging. Membranous adduction (monitored via videokymographic closed quotient) was influenced by both membranous medialization and cartilaginous adduction. Individual control over these types of vocal fold adjustments allows singers to create different vocal timbres.

The human voice spectrum above 5 kHz receives little attention. However, there are reasons to believe that this high-frequency energy (HFE) may play a role in perceived quality of voice in singing and speech. To fulfill this role, differences in HFE must first be detectable. To determine human ability to detect differences in HFE, the levels of the 8- and 16-kHz center-frequency octave bands were individually attenuated in sustained vowel sounds produced by singers and presented to listeners. Relatively small changes in HFE were in fact detectable, suggesting that this frequency range potentially contributes to the perception of especially the singing voice. Detection ability was greater in the 8-kHz octave than in the 16-kHz octave and varied with band energy level.

A method for analyzing and displaying electroglottographic (EGG) signals (and their first derivative, DEGG) is introduced: the electroglottographic wavegram ("wavegram" hereafter). To construct a wavegram, the time-varying fundamental frequency is measured and consecutive individual glottal cycles are identified. Each cycle is locally normalized in duration and amplitude, the signal values are encoded by color intensity and the cycles are concatenated to display the entire voice sample in a single image, similar as in sound spectrography. The wavegram provides an intuitive means for quickly assessing vocal fold contact phenomena and their variation over time. Variations in vocal fold contact appear here as a sequence of events rather than single phenomena, taking place over a certain period of time, and changing with pitch, loudness and register. Multiple DEGG peaks are revealed in wavegrams to behave systematically, indicating subtle changes of vocal fold oscillatory regime. As such, EGG wavegrams promise to reveal more information on vocal fold contacting and de-contacting events than previous methods.

Twelve sopranos with different levels of expertise (4 nonexperts, 4 advanced, 4 professionals) sustained pitches from A4 ( approximately 440 Hz) to their highest pitch (ranging from C6 to D7, i.e., from approximately 1000 to 2300 Hz). The frequencies of their first two vocal tract resonances (R1 and R2) were measured by broadband excitation at the mouth and compared with the voice harmonics (f(0), 2f(0), etc). Lip articulation was measured from simultaneous video recordings. Adjustment of R1 near to f(0) (R1:f(0) tuning) was observed below C6 to D6 ( approximately 1000-1200 Hz) for both expert and non-expert singers. Experts began this tuning at lower pitches. Some singers combine R2:2f(0) adjustment with R1:f(0) tuning. Some singers increased mouth area with increasing pitch over the whole R1:f(0) tuning range. Other singers showed this strategy on the higher part of the R1:f(0) range only, and used another, as yet unidentified, articulatory strategy on the lower part. To achieve very high pitches, some singers extended the range of R1:f(0) tuning as far as E6 to F#6 ( approximately 1300-1500 Hz) while others adjusted R2 near f(0) over the highest pitch range.

Human voice originates from the three-dimensional (3D) oscillations of the vocal folds. In previous studies, biomechanical properties of vocal fold tissues have been predicted by optimizing the parameters of simple two-mass-models to fit its dynamics to the high-speed imaging data from the clinic. However, only lateral and longitudinal displacements of the vocal folds were considered. To extend previous studies, a 3D mass-spring, cover-model is developed, which predicts the 3D vibrations of the entire medial surface of the vocal fold. The model consists of five mass planes arranged in vertical direction. Each plane contains five longitudinal, mass-spring, coupled oscillators. Feasibility of the model is assessed using a large body of dynamical data previously obtained from excised human larynx experiments, in vivo canine larynx experiments, physical models, and numerical models. Typical model output was found to be similar to existing findings. The resulting model enables visualization of the 3D dynamics of the human vocal folds during phonation for both symmetric and asymmetric vibrations.

This investigation compares vocal tract dimensions and the classification of singer voices by examining an x-ray material assembled between 1959 and 1991 of students admitted to the solo singing education at the University of Music, Dresden, Germany. A total of 132 images were available to analysis. Different classifications' values of the lengths of the total vocal tract, the pharynx, and mouth cavities as well as of the relative position of the larynx, the height of the palatal arch, and the estimated vocal fold length were analyzed statistically, and some significant differences were found. The length of the pharynx cavity seemed particularly influential on the total vocal tract length, which varied systematically with classification. Also studied were the relationships between voice classification and the body height and weight and the body mass index. The data support the hypothesis that there are consistent morphological vocal tract differences between singers of different voice classifications.

The importance of rural soundscape has been recently recognized for the recreational and amenity value, where man-made noise is at a low level and the dominance of natural sounds promotes sound preference, but there is a lack of studies on the sound preference of residents in the villages of China, which are undergoing a fast development in urbanization. In this study, a questionnaire survey was undertaken at 36 villages of northeast regions, representing all major soundscape types. The results show that among the individual factors, age, education level, and landscape environment are more significant than the factor of gender, in terms of influence on sound preference. With increasing age, the sound preference of traffic and mechanical sound has a tendency of increase and then decrease, whereas the tendency for human voice, natural, and melody sound is opposite. With a higher education level, the sound preference of traffic, mechanical sound, and human voice decreases, and on the contrary, sound preference for natural and melody sound increases. However, the evaluation of natural and melody sound is lower in better landscape environment, which is perhaps due to the residents’ higher requirements in soundscapes corresponding to the landscapes.

Voice control is of great importance in a singer’s training, and in particular, control of pitch (fundamental frequency) and volume (sound pressure level). We hypothesize that a singer’s vocal comfort and control will be increased as the acoustic feedback of the room is increased. In this study, 20 singers (10 amateur and 10 professional singers) performed vocal tasks in different acoustic conditions. Vocal tasks comprised scales and arpeggios with different dynamics at different speeds, and an extract from the American National Anthem, which was accompanied by a musical track emitted at different power levels. After each condition, the subject responded to questions regarding perception of vocal comfort, control, and fatigue, and their own voice feedback. Room acoustics were manipulated: in some conditions, two reflective panels were placed at different distances from the subject. The results indicate that when panels were present, singers tended to perceive the room as being more pleasant to sing in. In...

Although the signature of human voice is mostly tonal, it also includes a significant broadband component. Quadrupolelike sources due to turbulence in the region downstream of the glottis, and dipolelike sources due to the force applied by the vocal folds onto the surrounding fluid are the two primary broadband sound generating mechanisms. In this study, experiments were conducted to characterize the broadband sound emissions of confined stationary jets through rubber orifices formed to imitate the approximate shape of the human glottis at different stages during one cycle of vocal fold vibrations. The radiated sound pressure spectra downstream of the orifices were measured for varying flow rates, orifice shapes, and gas mixtures. The nondimensional sound pressure spectra were decomposed into the product of three functions: a source function F, a radiation efficiency function M, and an acoustic response function G. The results show that, as for circular jets, the quadrupole source contributions dominated for straight and convergent orifices. For divergent jets, whistling tonal sounds were emitted at low flow rates. At high flow rates for the same geometry, dipole contributions dominated the sound radiated by free jets. However, possible source-load acoustic feedback may have hampered accurate source identification in confined flows.

A new microphone system was developed to monitor the human voice near the microphone in a noisy environment. The system is equipped with two special functions in addition to the usual microphone functions: reduction of air-blow effects by the mouth and focused reception to a sound source. A wind filter was developed to reduce the air-blow effects from the mouth during speaking. This filter is a plate perforated by an array of small holes; the method used to design the filter is also presented. To achieve focused reception, four microphones were used in conjunction with a new signal-processing method. The proposed signal-processing method effectively increases the directivity in the desired direction. Additionally, it provides the system with focusing on the source since the source is located adjacent to the system. A prototype of the proposed system was fabricated and subjected to performance tests. The results showed that air-blow effects can be reduced by up to 20 dB and the directional gain is more than 4 dB. The proposed microphone system shows such good performance that it can be used in mobile phones for whispering communication.

Experiments using animal and human larynx models are often conducted without a vocal tract. While it is reasonable to assume the absence of a vocal tract has only small effects on vocal fold vibration, it is unclear how sound production and its perception will be affected. In this study, the validity of using data obtained in the absence of a vocal tract for voice perception studies was investigated. Using a two-layer self-oscillating physical model, three series of voice stimuli were created: one produced with conditions of left-right symmetric vocal fold stiffness, and two with left-right asymmetries in vocal fold body stiffness. Each series included a set of stimuli created with a physical vocal tract, and a second set created without a physical vocal tract. Stimuli were re-synthesized to equalize the mean F0 for each series and normalized for amplitude. Listeners were asked to evaluate the three series in a sort-and-rate task. Multidimensional scaling analysis will be applied to examine the perceptual interaction between the voice source and the vocal tract resonances. [Work supported by NIH.]

The human voice produces acoustic energy at frequencies above 6 kHz. Energy in this high-frequency region has long been known to affect perception of speech and voice quality, but also provides non-qualitative information about a speech signal. This presentation will demonstrate how much useful information can be gleaned from the high frequencies with a report on studies where listeners were presented with only high-frequency energy extracted from speech and singing. Come to test your own abilities and decide if you can hear strange voices or just chirps and whistles in the high frequencies of human speech and voice.

One purpose of a sound reinforcement system is to increase the talker’s speech intelligibility. A common metric for speech intelligibility evaluation is the Speech Transmission Index (STI) defined by IEC-60268-16 Revision 4. The STI of a sound reinforcement system can be measured by inputting a stimulus signal into the sound system, which is modified by the system electronics, and radiated by the sound system loudspeakers to the audience seats. The stimulus signal can be input via a line level connection to the sound system or by playing the stimulus signal through a small loudspeaker that is picked-up by a sound system microphone. This latter approach factors the entire sound system signal chain from microphone input to loudspeaker output. STI measurements were performed on two sound systems, one in a reverberant room and the other in relatively non-reverberant room. Measurement results compare both signal input techniques using omnidirectional and hypercardioid sound system microphones and three loudspeakers claimed to be designed to have directivity characteristics similar to the human voice.