Pitch Strength Research Articles

Beyond Lombard: Quantitative changes due to noise and reverberation

Forty-five subjects performed a short vocal task in two different rooms: a variable-acoustics room and an anechoic chamber. The subjects were taken back and forth between the two rooms using a deception protocol. Each time they entered the variable-acoustics room, its acoustical characteristics had been changed without a change in visual appearance. The changing characteristics involved two background noise conditions and two reverberation conditions. Subjects responded to questions about their comfort and perception of the environmental changes. Analysis was performed on the second and third sentences of the rainbow passage. Objective acoustical metrics and perceptual responses were compared for the different settings. In contrast to males, females raised their fundamental frequency (F0) in concert with their raised vocal levels in response to changes in both loudness and reverberation. A high correlation existed between pitch strength and F0. Factor analysis also revealed that F0 and vocal level were more correlated in females than males.

Characteristics of Buddhist chanting in Japanese temples

Buddhist monks change the way of voice production according to the ceremony, and associated acoustical changes have not yet been examined scientifically. In this study, three kinds of chanting voices were recorded in Japanese Buddhist temples and analyzed. The difference in voice production between chanting and normal speech was reflected in the loudness, fundamental frequency, pitch strength, and spectral centroid, which is characterized by autocorrelation function. Voice production in each stage of Nembutsu-Wasan singing was characterized by the loudness, fundamental frequency, and pitch strength.

Brainstem encoding of speech and musical stimuli in congenital amusia: evidence from Cantonese speakers.

Congenital amusia is a neurodevelopmental disorder of musical processing that also impacts subtle aspects of speech processing. It remains debated at what stage(s) of auditory processing deficits in amusia arise. In this study, we investigated whether amusia originates from impaired subcortical encoding of speech (in quiet and noise) and musical sounds in the brainstem. Fourteen Cantonese-speaking amusics and 14 matched controls passively listened to six Cantonese lexical tones in quiet, two Cantonese tones in noise (signal-to-noise ratios at 0 and 20 dB), and two cello tones in quiet while their frequency-following responses (FFRs) to these tones were recorded. All participants also completed a behavioral lexical tone identification task. The results indicated normal brainstem encoding of pitch in speech (in quiet and noise) and musical stimuli in amusics relative to controls, as measured by FFR pitch strength, pitch error, and stimulus-to-response correlation. There was also no group difference in neural conduction time or FFR amplitudes. Both groups demonstrated better FFRs to speech (in quiet and noise) than to musical stimuli. However, a significant group difference was observed for tone identification, with amusics showing significantly lower accuracy than controls. Analysis of the tone confusion matrices suggested that amusics were more likely than controls to confuse between tones that shared similar acoustic features. Interestingly, this deficit in lexical tone identification was not coupled with brainstem abnormality for either speech or musical stimuli. Together, our results suggest that the amusic brainstem is not functioning abnormally, although higher-order linguistic pitch processing is impaired in amusia. This finding has significant implications for theories of central auditory processing, requiring further investigations into how different stages of auditory processing interact in the human brain.

Autocorrelation-Based Features for Speech Representation

This study investigates autocorrelation-based features as a potential basis for phonetic and syllabic distinctions. The work comes out of a theory of auditory signal processing based on central monaural autocorrelation and binaural crosscorrelation representations. Correlation-based features are used to predict monaural and binaural perceptual attributes that are important for the architectural acoustic design of concert halls: pitch, timbre, loudness, duration, reverberation-related coloration, sound direction, apparent source width, and envelopment (Ando, 1985, 1998; Ando and Cariani, 2009). The current study investigates the use of features of monaural autocorrelation functions (ACFs) for representing phonetic elements (vowels), syllables (CV pairs), and phrases using a small set of temporal factors extracted from the short-term running ACF. These factors include listening level (loudness), zero-lag ACF peak width (spectral tilt), τ1 (voice pitch period), φ1 (voice pitch strength), τe (effective duration of the ACF envelope, temporal repetitive continuity/contrast), segment duration, and Δφ1/Δt (the rate of pitch strength change, related to voice pitch attack-decay dynamics). Times at which ACF effective duration τe is minimal reflect rapid signal pattern changes that usefully demarcate segmental boundaries. Results suggest that vowels, CV syllables, and phrases can be distinguished on the basis of this ACF-derived feature set.

C-21 9イニングの連続投球に伴う投球動作の変化の運動学的解析(投げ)

The purpose of this study was to investigate kinematic changes in baseball pitching during a simulated baseball game. Six collegiate baseball players threw 15 hastball pitches per inning for 9 innings in an indoor laboratory with a 5-minute inning interval and 5-second pitching interval. Whole-body kinematic data were collected by a motion capture system and ball sped was measured with a speed gun. Pitch strength and Grip strength were also measured during each inning interval. No significant difference was found in the ball speed over the 9 innings, where the trunk was leaned forward in the later innings. The subjects demonstrated decreased pinch strength in the later innings althoug no such decrease was found in the grip strength. These results suggest that consective pitches would mainly affect pinch strength, which may not be a major determinant of ball speed.

Testing the contribution of spectral cues on pitch strength judgments in normal-hearing listeners

When a wideband harmonic tone complex (wHTC) is passed through a noise vocoder, the resulting sounds can have harmonic structures with large peak-to-valley ratios in the spectra, but little or no periodicity strength in the autocorrelation functions. Noise-vocoded wHTCs evoke simultaneous noise percepts and pitch percepts similar to those evoked by iterated rippled noises. We have previously shown that spectral cues do not appear to control behavioral responses of chinchillas to noise-vocoded wHTCs in a stimulus generalization task, but do appear to contribute to pitch strength judgments in normal-hearing listeners for noise-vocoded wHTCs relative to non-vocoded wHTCs. To further test the role of spectral cues, normal-hearing listeners judged the pitch strengths of noise-vocoded wHTCs relative to infinitely-iterated rippled noise (IIRN). Stimuli had harmonic structures with a fixed fundamental frequency of 500 Hz and were presented monaurally at 50 dB SL. Listeners’ judgments of pitch strength evoked by v...

The role of pitch strength in extracting speech from complex backgrounds

How do people extract a target speech signal from a chorus of other sounds including other speech sounds? And what are the central and peripheral auditory processes that make this possible, and that may fail in people with damaged auditory systems? These critical issues in speech and hearing science were of continuing interest to Sid Bacon throughout his career. As Sid has noted, the problem is multifaceted, and he chose to study many of the individual factors, as well as their interactions. In keeping with that approach, I will discuss how normal-hearing and hearing-impaired listeners use pitch to extract a target from a complex noise background. In one study, auditory stream segregation of iterated rippled noises (IRN) with varying pitch strengths was explored to understand the limits of tonality for separating two patterns of sounds. In a second study, voice pitch strength was investigated as a means to support perceptual separation of target and background speech, with a focus on either spectral or temporal characteristics of the speech sounds. Interactions between degree of tonality in speech and other factors related to perception of speech in background sound will be examined. [Work supported by NIH.]

Sound-based automatic neotropical sciaenid fishes identification: Cynoscion jamaicensis

We present a method to automatically identify sound emissions produced by sciaenid fishes, and in particular by Cynoscion jamaicensis. This species' sound emissions typically have a 24 Hz pulse repetition rate and a quasi-harmonic pattern can be appreciated in spectra, which produces a pitched quality in the sounds. The proposed method is based on long-term partial loudness, pulse repetition rate, pitch strength, and timbre statistics. Current results show an F-measure of 0.9.

Enhancement of speech perception in noise by periodicity processing: A neurobiological model and signal processing algorithm

The perceived loudness of sound increases with its tonality or periodicity, and the pitch strength of tones are linearly proportional to their sound pressure level. These observations suggest a fundamental relationship between pitch strength and loudness. This relationship may be explained by the superimposition of inputs to inferior colliculus neurons from cochlear nucleus chopper cells and phase locked spike trains from the lateral lemniscus. The regularity of chopper cell outputs increases for stimuli with periodicity at the same frequency as their intrinsic chopping rate. So inputs to inferior colliculus cells become synchronized for periodic stimuli, leading to increased likelihood that they will fire and increased salience of periodic signal components at the characteristic frequency of the inferior colliculus cell. A computer algorithm to enhance speech in noise was based on this model. The periodicity of the outputs of a Gammatone filter bank after each sound onset was determined by first sampling each filter channel at a range of typical chopper cell frequencies and then passing these amplitudes through a step function to simulate the firing of coincidence detecting neurons in the inferior colliculus. Filter channel amplification was based on the maximum accumulated spike count after each onset, resulting in increased amplitudes for filter channels with greater periodicity. The speech intelligibility of stimuli in noise was not changed when the algorithm was used to remove around 14dB of noise from stimuli with signal–noise ratios of around 0dB. This mechanism is a likely candidate for enhancing speech recognition in noise, and raises the proposition that pitch itself is an epiphenomenon that evolved from neural mechanisms that boost the hearing sensitivity of animals to vocalizations.

Basics and applications of psychoacoustics

The field of psychoacoustics studies relations between acoustic stimuli, defined in the physical domain, and the hearing sensations elicited by these stimuli. The plenary lecture will address questions of stimulus generation and presentation. Both traditional methods and more recent methods like wave field synthesis will be touched. Concerning hearing sensations, basic magnitudes as for example absolute thresholds or loudness, but also advanced topics like pitch strength will be covered. Applications of psychoacoustics will include rather different fields such as music, noise evaluation or audiology, and address also cognitive effects as well as audio-visual interactions.

Autocorrelation-based features for speech representation

This study investigates autocorrelation-based features as a potential basis for phonetic and syllabic distinctions. The work comes out of a theory of auditory signal processing based on central monaural autocorrelation and binaural crosscorrelation representations. Correlation-based features are used to predict monaural and binaural perceptual attributes that are important for the architectural acoustic design of concert halls: pitch, timbre, loudness, duration, reverberation-related coloration, sound direction, apparent source width, and envelopment (Ando, 1985, 1998; Ando and Cariani, 2009). The current study investigates the use of features of monaural autocorrelation functions (ACFs) for representing phonetic elements (vowels), syllables (CV pairs), and phrases using a small set of temporal factors extracted from the short-term running ACF. These factors include listening level (loudness), zero-lag ACF peak width (spectral tilt), τ1 (voice pitch period), φ1 (voice pitch strength), τe (effective duration of the ACF envelope, temporal repetitive continuity/contrast), segment duration, and Δφ1/Δt (the rate of pitch strength change, related to voice pitch attack-decay dynamics). Times at which ACF effective duration τe is minimal reflect rapid signal pattern changes that usefully demarcate segmental boundaries. Results suggest that vowels, CV syllables, and phrases can be distinguished on the basis of this ACF-derived feature set.

Autocorrelation function mechanism for pitch salience and cross-correlation function mechanism for sound localization revealed by magnetoencephalography

A model of primary sensations and spatial sensations is proposed by Ando (2001). The model of the auditory-brain system includes the autocorrelation function (ACF) and the interaural cross-correlation function (IACF) mechanisms. At present, environmental noises are evaluated by sound level such as equivalent continuous A-weighted sound pressure level (LAeq). However, we sometimes feel annoyed with sound with low sound level because of the quality. Sound quality can be characterized by factors obtained from ACF and IACF of sound. For example, pitch and pitch strength can be characterized by delay time and amplitude of the maximum peak of the ACF. Directional sensation can be characterized by delay time and amplitude of the maximum peak of the IACF. To verify the model, we investigated how ACF and IACF factors are coded in our human brain. The results indicated that delay time and amplitude of the maximum peak of the ACF and IACF are coded by the latency and strength of brain activity. In addition, we applied the model to analyze a Buddhist sutra chanted in temples. The results indicated that some characteristics of the sutra could be characterized by the ACF and IACF factors.

Evaluation of an Automated Procedure for Detecting Frequency-Following Responses in American and Chinese Neonates

To date, observations of the scalp-recorded frequency-following response (FFR) to voice pitch have depended on subjective interpretation of the experimenter. The purpose of this study was to develop and evaluate an automated procedure for detecting the presence of a response. Twenty American (9 boys, 1-3 days) and 20 Chinese (10 boys, 1-3 days) neonates were recruited. A Chinese monosyllable that mimicked the English vowel /i/ with a rising pitch (117-166 Hz) was used as the stimulus. Three objective indices (Frequency Error, Tracking Accuracy, and Pitch Strength) were computed from the recorded brain waves and the test results were compared with human judgments to calculate the sensitivity and specificity values. Results demonstrated that the automated procedure produced sensitivity values between 53-90% and specificity values between 80-100%, and could be used to assess the presence of an FFR for neonates who were born in a tonal or non-tonal language environment.

Task-related suppression of the brainstem frequency following response.

Recent evidence has shown top-down modulation of the brainstem frequency following response (FFR), generally in the form of signal enhancement from concurrent stimuli or from switching between attention-demanding task stimuli. However, it is also possible that the opposite may be true – the addition of a task, instead of a resting, passive state may suppress the FFR. Here we examined the influence of a subsequent task, and the relevance of the task modality, on signal clarity within the FFR. Participants performed visual and auditory discrimination tasks in the presence of an irrelevant background sound, as well as a baseline consisting of the same background stimuli in the absence of a task. FFR pitch strength and amplitude of the primary frequency response were assessed within non-task stimulus periods in order to examine influences due solely to general cognitive state, independent of stimulus-driven effects. Results show decreased signal clarity with the addition of a task, especially within the auditory modality. We additionally found consistent relationships between the extent of this suppressive effect and perceptual measures such as response time and proclivity towards one sensory modality. Together these results suggest that the current focus of attention can have a global, top-down effect on the quality of encoding early in the auditory pathway.

Pitch strength of noise-vocoded harmonic tone complexes in normal-hearing listeners.

To study the role of harmonic structure in pitch perception, normal-hearing listeners were tested using noise-vocoded harmonic tone complexes. When tested in a magnitude judgment procedure using vocoded versions generated with 2-128 channels, judgments of pitch strength increased systematically as the number of channels increased and reflected acoustic cues based on harmonic peak-to-valley ratio, but not cues based on periodicity strength. When tested in a fundamental frequency discrimination task, listeners correctly recognized the direction of pitch change with as few as eight noise-vocoded channels. The results suggest that spectral processing contributes substantially to pitch perception in normal-hearing listeners.

Listening level of music through headphones in train car noise environments

Although portable music devices are useful for passing time on trains, exposure to music using headphones for long periods carries the risk of damaging hearing acuity. The aim of this study is to examine the listening level of music through headphones in the noisy environment of a train car. Eight subjects adjusted the volume to an optimum level (L(music)) in a simulated noisy train car environment. In Experiment I, the effects of noise level (L(train)) and type of train noise (rolling, squealing, impact, and resonance) were examined. Spectral and temporal characteristics were found to be different according to the train noise type. In Experiment II, the effects of L(train) and type of music (five vocal and five instrumental music) were examined. Each music type had a different pitch strength and spectral centroid, and each was evaluated by φ(1) and W(φ(0)), respectively. These were classified as factors of the autocorrelation function (ACF) of the music. Results showed that L(music) increased as L(train) increased in both experiments, while the type of music greatly influenced L(music). The type of train noise, however, only slightly influenced L(music). L(music) can be estimated using L(train) and the ACF factors φ(1) and W(φ(0)).

Distortion products and their influence on representation of pitch-relevant information in the human brainstem for unresolved harmonic complex tones

Pitch experiments aimed at evaluating temporal pitch mechanism(s) often utilize complex sounds with only unresolved harmonic components, and a low-pass noise masker to eliminate the potential contribution of audible distortion products to the pitch percept. Herein we examine how: (i) masker induced reduction of neural distortion products (difference tone: DT; and cubic difference tone: CDT) alters the representation of pitch relevant information in the brainstem; and (ii) the pitch salience is altered when distortion products are reduced and/or eliminated. Scalp recorded brainstem frequency following responses (FFR) were recorded in normal hearing individuals using a complex tone with only unresolved harmonics presented in quiet, and in the presence of a low-pass masker at SNRs of +15, +5, and −5 dB. Difference limen for F0 discrimination (F0 DL) was obtained in quiet and in the presence of low-pass noise. Magnitude of DT components (with the exception of components at F0 and 2F0), and the CDT components decreased with increasing masker level. Neural pitch strength decreased with increasing masker level for both the envelope-related (FFRENV) and spectral-related (FFRSPEC) phase-locked activity. Finally, F0 DLs increased with decreasing SNRs suggesting poorer F0 discrimination with reduction of the distortion products. Collectively, these findings support the notion that both DT and CDT, as reflected in the FFRENV and FFRSPEC, respectively, influence both the brainstem representation of pitch relevant information and the pitch salience of the complex sounds.

Temporal and spatial characteristics of noise in train stations

The train noise in station (TNIS) can annoy passengers and reduce the speech intelligibility of the public address system in a station. Thus clarifying the acoustical characteristics of TNIS is important for the comfort and safety. Noise level was evaluated the equivalent continuous sound pressure level (LAeq). The sound diffuseness was evaluated by the interaural cross-correlation coefficient (IACC) from the interaural cross-correlation function. The pitch and pitch strength was evaluated by the delay time (t1) and amplitude (f1) of the first peak of the autocorrelation function. The LAeq and IACC of the TNIS in the underground station were higher and lower, respectively, than those in the ground station. The t1 and f1 of the TNIS in the underground station were stable and lower, respectively, than those in the ground station. When the train came into the station, the LAeq of the TNIS at the island platform were higher than that at the side platform. The result suggests that the underground island platform, which is one platform at the center and the rail tracks on the both sides, needs improvement in particular although it is most frequently adopted as newly constructed stations in Japan.

Sustained BOLD and theta activity in auditory cortex are related to slow stimulus fluctuations rather than to pitch

Human functional MRI (fMRI) and magnetoencephalography (MEG) studies indicate a pitch-specific area in lateral Heschl's gyrus. Single-cell recordings in monkey suggest that sustained-firing, pitch-specific neurons are located lateral to primary auditory cortex. We reevaluated whether pitch strength contrasts reveal sustained pitch-specific responses in human auditory cortex. Sustained BOLD activity in auditory cortex was found for iterated rippled noise (vs. noise or silence) but not for regular click trains (vs. jittered click trains or silence). In contrast, iterated rippled noise and click trains produced similar pitch responses in MEG. Subsequently performed time-frequency analysis of the MEG data suggested that the dissociation of cortical BOLD activity between iterated rippled noise and click trains is related to theta band activity. It appears that both sustained BOLD and theta activity are associated with slow non-pitch-specific stimulus fluctuations. BOLD activity in the inferior colliculus was sustained for both stimulus types and varied neither with pitch strength nor with the presence of slow stimulus fluctuations. These results suggest that BOLD activity in auditory cortex is much more sensitive to slow stimulus fluctuations than to constant pitch, compromising the accessibility of the latter. In contrast, pitch-related activity in MEG can easily be separated from theta band activity related to slow stimulus fluctuations.

Pitch strength of normal and dysphonic voices

Two sounds with the same pitch may vary from each other based on saliency of their pitch sensation. This perceptual attribute is called "pitch strength." The study of voice pitch strength may be important in quantifying of normal and pathological qualities. The present study investigated how pitch strength varies across normal and dysphonic voices. A set of voices (vowel /a/) selected from the Kay Elemetrics Disordered Voice Database served as the stimuli. These stimuli demonstrated a wide range of voice quality. Ten listeners judged the pitch strength of these stimuli in an anchored magnitude estimation task. On a given trial, listeners heard three different stimuli. The first stimulus represented very low pitch strength (wide-band noise), the second stimulus consisted of the target voice and the third stimulus represented very high pitch strength (pure tone). Listeners estimated pitch strength of the target voice by positioning a continuous slider labeled with values between 0 and 1, reflecting the two anchor stimuli. Results revealed that listeners can judge pitch strength reliably in dysphonic voices. Moderate to high correlations with perceptual judgments of voice quality suggest that pitch strength may contribute to voice quality judgments.