Hearing myself with others: Sound levels in choral performance measured with separation of one's own voice from the rest of the choir

The choir singer has two acoustic signals to attend to: the sound of his or her own voice (feedback), and the sound of the rest of the choir (reference). The balance in loudness between feedback and reference is governed mainly by the room acoustics. Although earlier experiments have shown that singers have a fairly large tolerance for imbalance, with references ranging from −23 to +5 dB, experience suggests that, when singers are given control over this parameter, their preferences are much narrower. A quantification of the optimum balance would be useful in the design of concert stages and rehearsal halls. A method is described for measuring the feedback and reference levels as experienced by singers under live performance conditions. Recordings were made using binaural microphones worn by choir singer subjects. With the given combination of choir and room, it was possible to achieve adequate separation of the feedback and reference signals with simple signal processing. The feedback-to-reference ratio averaged over the 12 singers was found to be +3.9 dB, with extremes of +1.5 and +7.3 dB.     

Compensatory responses to loudness-shifted voice feedback during production of Mandarin speech

Previous studies have demonstrated that perturbations in voice pitch or loudness feedback lead to compensatory changes in voice F(0) or amplitude during production of sustained vowels. Responses to pitch-shifted auditory feedback have also been observed during English and Mandarin speech. The present study investigated whether Mandarin speakers would respond to amplitude-shifted feedback during meaningful speech production. Native speakers of Mandarin produced two-syllable utterances with focus on the first syllable, the second syllable, or none of the syllables, as prompted by corresponding questions. Their acoustic speech signal was fed back to them with loudness shifted by +/-3 dB for 200 ms durations. The responses to the feedback perturbations had mean latencies of approximately 142 ms and magnitudes of approximately 0.86 dB. Response magnitudes were greater and latencies were longer when emphasis was placed on the first syllable than when there was no emphasis. Since amplitude is not known for being highly effective in encoding linguistic contrasts, the fact that subjects reacted to amplitude perturbation just as fast as they reacted to F(0) perturbations in previous studies provides clear evidence that a highly automatic feedback mechanism is active in controlling both F(0) and amplitude of speech production.     

Effects of HearFones on speaking and singing voice quality

HearFones (HF) have been designed to enhance auditory feedback during phonation. This study investigated the effects of HF (1) on sound perceivable by the subject, (2) on voice quality in reading and singing, and (3) on voice production in speech and singing at the same pitch and sound level.

Test 1: Text reading was recorded with two identical microphones in the ears of a subject. One ear was covered with HF, and the other was free. Four subjects attended this test. Tests 2 and 3: A reading sample was recorded from 13 subjects and a song from 12 subjects without and with HF on. Test 4: Six females repeated [pa:p:a] in speaking and singing modes without and with HF on same pitch and sound level.

Long-term average spectra were made (Tests 1–3), and formant frequencies, fundamental frequency, and sound level were measured (Tests 2 and 3). Subglottic pressure was estimated from oral pressure in [p], and simultaneously electroglottography (EGG) was registered during voicing on [a:] (Test 4). Voice quality in speech and singing was evaluated by three professional voice trainers (Tests 2–4).

HF seemed to enhance sound perceivable at the whole range studied (0–8 kHz), with the greatest enhancement (up to ca 25 dB) being at 1–3 kHz and at 4–7 kHz. The subjects tended to decrease loudness with HF (when sound level was not being monitored). In more than half of the cases, voice quality was evaluated “less strained” and “better controlled” with HF. When pitch and loudness were constant, no clear differences were heard but closed quotient of the EGG signal was higher and the signal more skewed, suggesting a better glottal closure and/or diminished activity of the thyroarytenoid muscle.     

Vocal responses to unanticipated perturbations in voice loudness feedback: an automatic mechanism for stabilizing voice amplitude

The present study tested whether subjects respond to unanticipated short perturbations in voice loudness feedback with compensatory responses in voice amplitude. The role of stimulus magnitude (+/- 1,3 vs 6 dB SPL), stimulus direction (up vs down), and the ongoing voice amplitude level (normal vs soft) were compared across compensations. Subjects responded to perturbations in voice loudness feedback with a compensatory change in voice amplitude 76% of the time. Mean latency of amplitude compensation was 157 ms. Mean response magnitudes were smallest for 1-dB stimulus perturbations (0.75 dB) and greatest for 6-dB conditions (0.98 dB). However, expressed as gain, responses for 1-dB perturbations were largest and almost approached 1.0. Response magnitudes were larger for the soft voice amplitude condition compared to the normal voice amplitude condition. A mathematical model of the audio-vocal system captured the main features of the compensations. Previous research has demonstrated that subjects can respond to an unanticipated perturbation in voice pitch feedback with an automatic compensatory response in voice fundamental frequency. Data from the present study suggest that voice loudness feedback can be used in a similar manner to monitor and stabilize voice amplitude around a desired loudness level.     

Comparison of the Produced and Perceived Voice Range Profiles in Untrained and Trained Classical Singers

Frequency and intensity ranges (in true decibel sound pressure level, 20 microPa at 1 m) of voice production in trained and untrained vocalists were compared with the perceived dynamic range (phons) and units of loudness (sones) of the ear. Results were reported in terms of standard voice range profiles (VRPs), perceived VRPs (as predicted by accepted measures of auditory sensitivities), and a new metric labeled as an overall perceptual level construct. Trained classical singers made use of the most sensitive part of the hearing range (around 3-4 kHz) through the use of the singer's formant. When mapped onto the contours of equal loudness (depicting nonuniform spectral and dynamic sensitivities of the auditory system), the formant is perceived at an even higher sound level, as measured in phons, than a flat or A-weighted spectrum would indicate. The contributions of effects like the singer's formant and the sensitivities of the auditory system helped the trained singers produce 20% to 40% more units of loudness, as measured in sones, than the untrained singers. Trained male vocalists had a maximum overall perceptual level construct that was 40% higher than the untrained male vocalists. Although the A-weighted spectrum (commonly used in VRP measurement) is a reasonable first-order approximation of auditory sensitivities, it misrepresents the most salient part of the sensitivities (where the singer's formant is found) by nearly 10 dB.     

Functional magnetic resonance imaging measurements of sound-level encoding in the absence of background scanner noise

Effects of sound level on auditory cortical activation are seen in neuroimaging data. However, factors such as the cortical response to the intense ambient scanner noise and to the bandwidth of the acoustic stimuli will both confound precise quantification and interpretation of such sound-level effects. The present study used temporally "sparse" imaging to reduce effects of scanner noise. To achieve control for stimulus bandwidth, three schemes were compared for sound-level matching across bandwidth: component level, root-mean-square power and loudness. The calculation of the loudness match was based on the model reported by Moore and Glasberg [Acta Acust. 82, 335-345 (1996)]. Ten normally hearing volunteers were scanned using functional magnetic resonance imaging (tMRI) while listening to a 300-Hz tone presented at six different sound levels between 66 and 91 dB SPL and a harmonic-complex tone (F0= 186 Hz) presented at 65 and 85 dB SPL. This range of sound levels encompassed all three bases of sound-level matching. Activation in the superior temporal gyrus, induced by each of the eight tone conditions relative to a quiet baseline condition, was quantified as to extent and magnitude. Sound level had a small, but significant, effect on the extent of activation for the pure tone, but not for the harmonic-complex tone, while it had a significant effect on the response magnitude for both types of stimulus. Response magnitude increased linearly as a function of sound level for the full range of levels for the pure tone. The harmonic-complex tone produced greater activation than the pure tone, irrespective of the matching scheme for sound level, indicating that bandwidth had a greater effect on the pattern of auditory activation than sound level. Nevertheless, when the data were collapsed across stimulus class, extent and magnitude were significantly correlated with the loudness scale (measured in phons), but not with the intensity scale (measured in SPL). We therefore recommend the loudness formula as the most appropriate basis of matching sound level to control for loudness effects when cortical responses to other stimulus attributes, such as stimulus class, are the principal concern.     

The effect of loudness on the reverberance of music: reverberance prediction using loudness models

This study examines the auditory attribute that describes the perceived amount of reverberation, known as "reverberance." Listening experiments were performed using two signals commonly heard in auditoria: excerpts of orchestral music and western classical singing. Listeners adjusted the decay rate of room impulse responses prior to convolution with these signals, so as to match the reverberance of each stimulus to that of a reference stimulus. The analysis examines the hypothesis that reverberance is related to the loudness decay rate of the underlying room impulse response. This hypothesis is tested using computational models of time varying or dynamic loudness, from which parameters analogous to conventional reverberation parameters (early decay time and reverberation time) are derived. The results show that listening level significantly affects reverberance, and that the loudness-based parameters outperform related conventional parameters. Results support the proposed relationship between reverberance and the computationally predicted loudness decay function of sound in rooms.     

A system for simulating room acoustical environments for one’s own voice

The real-time simulation of room acoustical environments for one’s own voice using generic software has been difficult until very recently due to the computational load involved: requiring real-time convolution of a person’s voice with a potentially large number of long room impulse responses. This paper describes a software-based solution that accomplishes real-time convolution with head-tracking to simulate the effect of room acoustical environments on the sound of one’s own voice, using binaural technology. Actual rooms are characterized by measuring the room impulse response from the mouth to ears of the same head (oral binaural room impulse response, OBRIR). By repeating this process at 2° yaw increments for a given head position, the rooms are binaurally scanned around a given position to obtain a collection of OBRIRs, which is then used by the software-based simulation system. In the simulated rooms, a person equipped with a near-mouth microphone and near-ear loudspeakers can speak or sing and hear their voice, as it would sound in the recorded rooms, while physically being in an anechoic room. By continually updating the person’s head orientation using head-tracking, the corresponding OBRIR is chosen for convolution with their voice. The system described in this paper achieves the low latency that is required to simulate nearby reflections, and it can perform convolution with long room impulse responses.     

Comment on "Increase in voice level and speaker comfort in lecture rooms" [J. Acoust. Soc. Am. 125, 2072-2082 (2009)] (L)

Recently, a paper written by Brunskog Gade, Paya?-Ballester and Reig-Calbo, "Increase in voice level and speaker comfort in lecture rooms" [J. Acoust. Soc. Am. 125, 2072-2082 (2009)] related teachers' variation in vocal intensity during lecturing to the room acoustic conditions, introducing an objective parameter called "room gain" to describe these variations. In a failed attempt to replicate the objective measurements by Brunskog et al., a simplified and improved method for the calculation of room gain is proposed, in addition with an alternative magnitude called "voice support." The measured parameters are consistent with those of other studies and are used here to build two empirical models relating the voice power levels measured by Brunskog et al., to the room gain and the voice support.     

The sound level of the singer's formant in professional singing

The relative sound level of the "singer's formant," measured in a 1/3-oct band with a center frequency of 2.5 kHz for males and of 3.16 kHz for females, has been investigated for 14 professional singers, nine different modes of singing, nine different vowels, variations in overall sound-pressure level, and fundamental frequencies ranging from 98 up to 880 Hz. Variation in the sound level of the singer's formant due to differences among male singers was small (4 dB), the factors vowels (16 dB) and fundamental frequency (9-14 dB) had an intermediate effect, while the largest variation was found for differences among female singers (24 dB), between modes of singing (vocal effort) (23 dB), and in overall sound-pressure level (more than 30 dB). In spite of this great potential variability, for each mode of singing the sound level of the singer's formant was remarkably constant up to F0 = 392 Hz, due to adaptation of vocal effort. This may be explained as the result of the perceptual demand of a constant voice quality. The definition of the singer's formant is discussed.     

The use of an auditory model in predicting perceptual ratings of breathy voice quality

Despite much research, the relationship between vocal acoustic signals and perceived voice quality is not well understood. The present study used an auditory model proposed by Moore et al¹⁰ to study how changes in the acoustic spectrum may relate to changes in perceptual ratings of breathiness. Perceptual ratings of breathiness were obtained using a multidimensional scaling (MDS) design. The stimulus distances on the dominant MDS dimension were correlated with several commonly used acoustic measures for voice quality. These distances were also compared with measures obtained from the output of the auditory model. Results show that the partial loudness of the harmonic energy obtained with the aspiration noise acting as a masker was the most important predictor of perceptual ratings of breathiness. Results also demonstrate that measures obtained from the auditory spectrum were better predictors of perceptual ratings of breathiness than were commonly used acoustic spectral measures.     

使用者的社会因素对地下商业街主观响度和声舒适度影响的调查研究

前人研究表明主观响度和声舒适度由实际环境中的众多因素决定,而不是仅受声压级的影响。本文在对地下商业街声场和声源特性进行调查与分析的基础上,针对使用者的社会因素对主观响度和声舒适度的影响,在哈尔滨的几个典型地下商业街进行了大量问卷调查,并运用相关统计方法对结果进行了分析。研究表明,收入和职业与主观响度存在相关性,相关系数在0.1～0.4之间,学历、收入和职业与主观声舒适度亦存在相关性,相关系数在0.1～0.6之间。虽然性别对主观响度和主观声舒适度无显著性影响,但是女性对这两者的主观感觉评分范围比男性宽。年龄段与主观响度和声舒适度的相关性不显著,但是不同地下商业街有的年龄段对主观响度和声舒适度的感受有区别。职业对于主观声舒适度的影响的本质是源于收入和学历对于主观声舒适度的作用,并且收入对于主观声舒适度的影响要大于学历的影响。这些结果可以增加对地下商业街声景的了解,并且为建立地下商业街声景预测模型提供了基础。     

Subjective loudness level measurements and equal loudness contours in a bottlenose dolphin (Tursiops truncatus)

Loudness level measurements in human listeners are straightforward; however, it is difficult to convey the concepts of loudness matching or loudness comparison to (non-human) animals. For this reason, prior studies have relied upon objective measurements, such as response latency, to estimate equal loudness contours in animals. In this study, a bottlenose dolphin was trained to perform a loudness comparison test, where the listener indicates which of two sequential tones is louder. To enable reward of the dolphin, most trials featured tones with identical or similar frequencies, but relatively large sound pressure level differences, so that the loudness relationship was known. A relatively small percentage of trials were "probe" trials, with tone pairs whose loudness relationship was not known. Responses to the probe trials were used to construct psychometric functions describing the loudness relationship between a tone at a particular frequency and sound pressure level and that of a reference tone at 10 kHz with a sound pressure level of 90, 105, or 115 dB re 1 μPa. The loudness relationships were then used to construct equal loudness contours and auditory weighting functions that can be used to predict the frequency-dependent effects of noise on odontocetes.     

Speakers' comfort and voice level variation in classrooms: laboratory research

Teachers adjust their voice levels under different classroom acoustics conditions, even in the absence of background noise. Laboratory experiments have been conducted in order to understand further this relationship and to determine optimum room acoustic conditions for speaking. Under simulated acoustic environments, talkers do modify their voice levels linearly with the measure voice support, and the slope of this relationship is referred to as room effect. The magnitude of the room effect depends highly on the instruction used and on the individuals. Group-wise, the average room effect ranges from -0.93 dB/dB, with free speech, to -0.1 dB/dB with other less demanding communication tasks as reading and talking at short distances. The room effect for some individuals can be as strong as -1.7 dB/dB. A questionnaire investigation showed that the acoustic comfort for talking in classrooms, in the absence of background noise, is correlated to the decay times derived from an impulse response measured from the mouth to the ears of a talker, and that there is a maximum of preference for decay times between 0.4 and 0.5 s. Teachers with self-reported voice problems prefer higher decay times to speak in than their healthy colleagues.     

Airborne Acoustic Transmission and Terrain Topography at SAINTGITS Amphitheatre: An Analysis of Outdoor Auditory Perception and Comparison of Contour Plots

The arrangement of natural and physical features on the earth’s surface are a few among the countless items that govern the airborne acoustic transmission at boundary layers. In particular, if the acoustic waves are attributes of live concerts at open-air theatres, without losing the sheen and quality, the audience should certainly receive the unbroken depth of the performance. Hence, at all times, it is advisable to analyse the auditory receptiveness, particularly in all intended recreational spaces. The current pandemic circumstances and the mandated COVID-19 prevention protocols encourage gatherings in naturally ventilated outdoor regions than confined indoors. This work predicts and quantifies the acoustic experience at the naturally carved amphitheatre at SAINTGITS, an autonomous institution at the down South-West of the Indian Subcontinent. The entire recreational space at SAINTGITS AMPHI was separately modelled as a Base case and Advanced case, and were analysed using the acoustic modelling module of EASE Focus, a renowned simulation freeware, which is in strict adherence with the International standards. The variation in loudness received at the nearest and farthest ends of the amphitheatre was between 67 to 80 dB. Though the Zero frequency SPL (Z-weighting) exhibited the loudness in the range of 81 to 85 dB and could maintain a safer auditory level for any human ear, it was confined to a hemispherical region near the sound source. A vertical beam angle of −4.0° was found to be effective throughout. The procedures and analyses will certainly help the future organizers and stakeholders to effectively plan the resources to reap rich acoustic experience at terrain-centric locales. The surface topography and contours were plotted with another set of freeware, the CADMAPPER and the QUIKGRID, to compare terrain gradient with the known data. Furthermore, this interdisciplinary research exhibits the extensive simulation capability of both EASE Focus and QUIKGRID and demonstrates the modelling versatility and deliverable potential of these freeware to benefit the budding architects and researchers.     

Effect of diffusive and nondiffusive surfaces combinations on sound diffusion

One of room acoustic goals, especially in small to medium rooms, is sound diffusion in low frequencies, which have been the subject of lots of researches. Sound diffusion is a very important consideration in acoustics because it minimizes the coherent reflections that cause problems. It also tends to make an enclosed space sound larger than it is. Diffusion is an excellent alternative or complement to sound absorption in acoustic treatment because it doesn’t really remove much energy, which means it can be used to effectively reduce reflections while still leaving an ambient or live sounding space. Distribution of diffusive and nondiffusive surfaces on room walls affect sound diffusion in room, but the amount, combination, and location of these surfaces are still the matter of question. This paper investigates effects of these issues on room acoustic frequency response in different parts of the room with different source-receiver locations. Room acoustic model based on wave method is used (implemented) which is very accurate and convenient for low frequencies in such rooms. Different distributions of acoustic surfaces on room walls have been introduced to the model and room frequency response results are calculated. For the purpose of comparison, some measurements results are presented. Finally for more smooth frequency response in small and medium rooms, some suggestions are made.     

Relationship between changes in voice pitch and loudness

Changes in mean fundamental frequency accompanying changes in loudness of phonation are analyzed in 9 professional singers, 9 nonsingers, and 10 male and 10 female patients suffering from vocal functional dysfunction. The subjects read discursive texts with noise in earphones, and some also at voluntarily varied vocal loudness. The healthy subjects phonated as softly and as loudly as possible at various fundamental frequencies throughout their pitch ranges, and the resulting mean phonetograms are compared. Mean pitch was found to increase by about half-semitones per decibel sound level. Grossly, the subject groups gave similar results, although the singers changed voice pitch more than the nonsingers. The voice pitch changes may be explained as passive results of changes of subglottal pressure required for the sound level variation.     

Effects of vocal loudness variation on spectrum balance as reflected by the alpha measure of long-term-average spectra of speech

The overall slope of long-term-average spectrum (LTAS) decreases if vocal loudness increases. Therefore, changes of vocal loudness also affects the alpha measure, defined as the ratio of spectrum intensity above and below 1000 Hz. The effect on alpha of loudness variation was analyzed in 15 male and 16 female voices reading a text at different degrees of vocal loudness. The mean range of equivalent sound level (L(eq)) amounted to about 28 dB and the mean range of alpha to 19.0 and 11.7 dB for the female and male subjects. The L(eq) vs. alpha relationship could be approximated with a quadratic function, or by a linear equation, if softest phonation was excluded. Using such equations alpha was computed for all values of L(eq) observed for each subject and compared with observed values. The maximum and the mean absolute errors were 2.4 dB and between 0.1 and 0.6 dB. When softest phonation was disregarded and linear equations were used, the maximum error was less than 2 dB and the mean absolute errors were between 0.2 and 0.7 dB. The strong correlation between L(eq) and alpha indicates that for a voice L(eq) can be used for predicting alpha.     

Loudness criteria in auditorium acoustics

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