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PubMed2006

The singing power ratio as an objective measure of singing voice quality in untrained talented and nontalented singers.

A growing body of contemporary research has investigated differences between trained and untrained singing voices. However, few studies have separated untrained singers into those who do and do not express abilities related to singing talent, including accurate pitch control and production of a pleasant timbre (voice quality). This investigation studied measures of the singing power ratio (SPR), which is a quantitative measure of the resonant quality of the singing voice. SPR reflects the amplification or suppression in the vocal tract of the harmonics produced by the sound source. This measure was acquired from the voices of untrained talented and nontalented singers as a means to objectively investigate voice quality differences. Measures of SPR were acquired from vocal samples with fast Fourier transform (FFT) power spectra to analyze the amplitude level of the partials in the acoustic spectrum. Long-term average spectra (LTAS) were also analyzed. Results indicated significant differences in SPR between groups, which suggest that vocal tract resonance, and its effect on perceived vocal timbre or quality, may be an important variable related to the perception of singing talent. LTAS confirmed group differences in the tuning of vocal tract harmonics.

Acoustics↗
PubMed2005

Detection of sound rise time by adults with dyslexia.

Low sensitivity to amplitude modulated (AM) sounds is reported to be associated with dyslexia. An important aspect of amplitude modulation cycles are the rise and fall times within the sound. In this study, simplified stimuli equivalent to just one cycle were used and sensitivity to varying rise times was explored. Adult participants with dyslexia or compensated dyslexia and a control group performed a detection task with sound pairs of different rise times. Results showed that the participants with dyslexia differed from the control group in rise time detection and a correlation was found between rise time detection and reading and phonological skills. A subgroup of participants with lower sensitivity to rise time detection characterized by low accuracy in syllable-level phonological skills was found within the dyslexic group. Short stimuli containing only one rise time produced associations with phonological skills and reading, even in a language where the perception of rise time contrasts are not crucial for the signaling of phonemic contrast.

Acoustic Stimulation↗
PubMed1998

Bilateral cochlear implants controlled by a single speech processor.

OBJECTIVE: This study aimed to assess, in one profoundly hearing impaired subject, potential benefits and limitations in placing bilaterally implanted scala tympani electrode arrays under control of a single speech processor. STUDY DESIGN: All available stimulation sites in both ears were compared in studies of pitch discrimination and pitch ranking, identifying three bilateral pairs capable of supporting interaural comparisons with no perceptible difference in pitch. Using those pairs, the subject's ability to lateralize sound was studied as a function of interaural time delay and interaural amplitude difference. Consonant identification scores were obtained for continuous interleaved sampling processors using various unilateral and bilateral combinations of electrodes. RESULTS: For loudness-matched stimuli composed of 50-msec bursts of 80-microsec/phase pulses at 480 pulses/sec, the subject was able to identify the ear receiving the earlier onset for interaural delays at least as brief as 150 microsec for all three matched pairs. For similar simultaneous stimuli, the subject could identify the ear receiving the louder signal for the smallest deviations from loudness-matched amplitudes available from the implanted electronics. The consonant studies found no evidence that bilateral stimulation per se degrades speech processor performance, even for arbitrary divisions of information between the two ears. Additional contralateral as well as ipsilateral channels were observed to improve speech processor performance. CONCLUSIONS: The ability of this subject to lateralize sounds on the basis of interaural delay or loudness difference, combined with the consonant identification results, supports further use of coordinated binaural stimulation to improve cochlear implant users' ability to understand speech, especially in the presence of competing speech noise.

Adult↗
PubMed1994

Pitch ranking with nonsimultaneous dual-electrode electrical stimulation of the cochlea.

It has already been established that simultaneous activation of two intracochlear electrodes can evoke a pitch percept which is intermediate to that of either electrode when activated by itself. In the present study, this result has been extended to nonsimultaneous activation of nearby electrodes. Pitch perception was investigated for electric stimuli presented on one or two intracochlear electrode pairs. All stimuli were pulse trains of period 4 ms. In the dual-electrode stimuli, each period contained two biphasic pulses, separated by 0.4 ms, with one pulse for each electrode pair. These stimuli were compared with loudness-balanced single-electrode stimuli, having one pulse per period, generated on the same electrode pairs. Their pitches were ranked in a two-alternative forced-choice procedure by five experienced users of the 22-electrode implant manufactured by Cochlear Pty Limited. The studies showed that the pitch of a dual-electrode stimulus was intermediate to, and moved monotonically between, those of the component electrode pairs as the relative currents were altered in an orderly fashion. Intermediate pitches were achieved in all subjects at a range of cochlear positions, for electrode separations generally up to 3 mm. In half the cases a significantly different intermediate pitch could be created between adjacent electrodes. Further studies are necessary to establish whether intermediate pitches can be obtained at larger separations, as for simultaneous stimulation, and how they are affected by other factors such as the time between pulses or the spatial extent of the stimulation.

Cochlea↗
PubMed2004

Speech perception benefits of FM and infrared devices to children with hearing aids in a typical classroom.

UNLABELLED: Children typically learn in classroom environments that have background noise and reverberation that interfere with accurate speech perception. Amplification technology can enhance the speech perception of students who are hard of hearing. PURPOSE: This study used a single-subject alternating treatments design to compare the speech recognition abilities of children who are, hard of hearing when they were using hearing aids with each of three frequency modulated (FM) or infrared devices. METHOD: Eight 9-12-year-olds with mild to severe hearing loss repeated Hearing in Noise Test (HINT) sentence lists under controlled conditions in a typical kindergarten classroom with a background noise level of +10 dB signal-to-noise (S/N) ratio and 1.1 s reverberation time. Participants listened to HINT lists using hearing aids alone and hearing aids in combination with three types of S/N-enhancing devices that are currently used in mainstream classrooms: (a) FM systems linked to personal hearing aids, (b) infrared sound field systems with speakers placed throughout the classroom, and (c) desktop personal sound field FM systems. RESULTS: The infrared ceiling sound field system did not provide benefit beyond that provided by hearing aids alone. Desktop and personal FM systems in combination with personal hearing aids provided substantial improvements in speech recognition. CLINICAL IMPLICATIONS: This information can assist in making S/N-enhancing device decisions for students using hearing aids. In a reverberant and noisy classroom setting, classroom sound field devices are not beneficial to speech perception for students with hearing aids, whereas either personal FM or desktop sound field systems provide listening benefits.

Child↗
PubMed2003

Pitch of amplitude-modulated irregular-rate stimuli in acoustic and electric hearing.

The pitch of stimuli was studied under conditions where place-of-excitation was held constant, and where pitch was therefore derived from "purely temporal" cues. In experiment 1, the acoustical and electrical pulse trains consisted of pulses whose amplitudes alternated between a high and a low value, and whose interpulse intervals alternated between 4 and 6 ms. The attenuated pulses occurred after the 4-ms intervals in condition A, and after the 6-ms intervals in condition B. For both normal-hearing subjects and cochlear implantees, the period of an isochronous pulse train equal in pitch to this "4-6" stimulus increased from near 6 ms at the smallest modulation depth to nearly 10 ms at the largest depth. Additionally, the modulated pulse trains in condition A were perceived as being lower in pitch than those in condition B. Data are interpreted in terms of increased refractoriness in condition A, where the larger pulses are more closely followed by the smaller ones than in condition B. Consistent with this conclusion, the A-B difference was reduced at longer interpulse intervals. These findings provide a measure of supra-threshold effects of refractoriness on pitch perception, and increase our understanding of coding of temporal information in cochlear implant speech processing schemes.

Acoustic Stimulation↗
PubMed2003

Auditory influences on visual temporal rate perception.

Visual stimuli are known to influence the perception of auditory stimuli in spatial tasks, giving rise to the ventriloquism effect. These influences can persist in the absence of visual input following a period of exposure to spatially disparate auditory and visual stimuli, a phenomenon termed the ventriloquism aftereffect. It has been speculated that the visual dominance over audition in spatial tasks is due to the superior spatial acuity of vision compared with audition. If that is the case, then the auditory system should dominate visual perception in a manner analogous to the ventriloquism effect and aftereffect if one uses a task in which the auditory system has superior acuity. To test this prediction, the interactions of visual and auditory stimuli were measured in a temporally based task in normal human subjects. The results show that the auditory system has a pronounced influence on visual temporal rate perception. This influence was independent of the spatial location, spectral bandwidth, and intensity of the auditory stimulus. The influence was, however, strongly dependent on the disparity in temporal rate between the two stimulus modalities. Further, aftereffects were observed following approximately 20 min of exposure to temporally disparate auditory and visual stimuli. These results show that the auditory system can strongly influence visual perception and are consistent with the idea that bimodal sensory conflicts are dominated by the sensory system with the greater acuity for the stimulus parameter being discriminated.

Acoustic Stimulation↗
PubMedDate not supplied

[Hearing disorders in patients with adhesive otitis media].

This paper presents the results of audiological examinations of 76 patients, aged 18 to 60 years, with adhesive nonperforative otitis media. The hearing function was measured in terms of threshold tonal audiometry, ultrasound hearing sensitivity, lower limit of sound frequency perception, discomfortable loudness, dynamic range of the hearing field, speech intelligibility in the masking noisy environment. In 30% of cases hypoacusis accompanying adhesive otitis media showed symptoms that were similar to those of hypoacusis resulting from inner ear pathologies (descending audiometric curves with high hearing thresholds related to bone conduction and small bone-air interval, high thresholds of ultrasound perception, normal lower limits of sound frequency perception and positive recruitment). Study of speech intellibility in a masking noisy environment can be a good test for the diagnosis of adhesive otitis media, including the cases aggravated with secondary cochlear neuritis. The pathognomonic parameter is good speech intelligibility in both silent and noisy environments.

Cochlear Diseases↗
PubMed1995

Detectability of duration and intensity increments in melody tones: a partial connection between music perception and performance.

Two experiments demonstrate positional variation in the relative detectability of, respectively, local temporal and dynamic perturbations in an isochronous and isodynamic sequence of melody tones, played on a computer-controlled piano. This variation may reflect listeners' expectations of expressive performance microstructure (the top-down hypothesis), or it may be due to psychoacoustic (pitch-related) stimulus factors (the bottom-up hypothesis). Percent correct scores for increments in tone duration correlated significantly with the average timing profile of pianists' expressive performances of the music, as predicted specifically by the top-down hypothesis. For intensity increments, the analogous perception-performance correlation was weak and the bottom-up factors of relative pitch height and/or direction of pitch change accounted for some of the perceptual variation. Subjects' musical training increased overall detection accuracy but did not affect the positional variation in accuracy scores in either experiment. These results are consistent with the top-down hypothesis for timing, but they favor the bottom-up hypothesis for dynamics. The perception-performance correlation for timing may also be viewed as being due to complex stimulus properties such as tonal motion and tension/relaxation that influence performers and listeners in similar ways.

Adolescent↗
PubMed2005

Right hemisphere specialization for intensity discrimination of musical and speech sounds.

Sound intensity is the primary and most elementary feature of auditory signals. Its discrimination plays a fundamental role in different behaviours related to auditory perception such as sound source localization, motion detection, and recognition of speech sounds. This study was aimed at investigating hemispheric asymmetries for processing intensity of complex tones and consonant-vowel syllables. Forty-four right-handed non-musicians were presented with two dichotic matching-to-sample tests with focused attention: one with complex tones of different intensities (musical test) and the other with consonant-vowel syllables of different intensities (speech test). Intensity differences (60, 70, and 80 dBA) were obtained by altering the gain of a synthesized harmonic tone (260 Hz fundamental frequency) and of a consonant-vowel syllable (/ba/) recorded from a natural voice. Dependent variables were accuracy and reaction time. Results showed a significant clear-cut left ear advantage in both tests for both dependent variables. A monaural control experiment ruled out possible attentional biases. This study provides behavioural evidence of a right hemisphere specialization for the perception of the intensity of musical and speech sounds in healthy subjects.

Adult↗
PubMed1992

Acoustics and perception of overtone singing.

Overtone singing, a technique of Asian origin, is a special type of voice production resulting in a very pronounced, high and separate tone that can be heard over a more or less constant drone. An acoustic analysis is presented of the phenomenon and the results are described in terms of the classical theory of speech production. The overtone sound may be interpreted as the result of an interaction of closely spaced formants. For the lower overtones, these may be the first and second formant, separated from the lower harmonics by a nasal pole-zero pair, as the result of a nasalized articulation shifting from /c/ to /a/, or, as an alternative, the second formant alone, separated from the first formant by the nasal pole-zero pair, again as the result of a nasalized articulation around /c/. For overtones with a frequency higher than 800 Hz, the overtone sound can be explained as a combination of the second and third formant as the result of a careful, retroflex, and rounded articulation from /c/, via schwa /e/ to /y/ and /i/ for the highest overtones. The results indicate a firm and relatively long closure of the glottis during overtone phonation. The corresponding short open duration of the glottis introduces a glottal formant that may enhance the amplitude of the intended overtone. Perception experiments showed that listeners categorized the overtone sounds differently from normally sung vowels, which possibly has its basis in an independent perception of the small bandwidth of the resonance underlying the overtone. Their verbal judgments were in agreement with the presented phonetic-acoustic explanation.

Fourier Analysis↗
PubMed1984

Perception of temporal differences in speech by "normal-hearing" adults: effects of age and intensity.

Many older people have greater difficulty processing speech at suprathreshold levels than can be explained by standard audiometric configurations. Some of the difficulty may involve the processing of temporal information. Temporal information can signal linguistic distinctions. The voicing distinction, for example, that separates pairs of words such as "rapid" and "rabid" can be signaled by temporal information: longer first vowel and shorter closure characterize "rabid"; shorter vowel and longer closure characterize "rapid." In this study, naturally produced tokens of "rabid" were low-pass filtered at 3500 Hz and edited to create vowel and (silent) closure duration continua. Pure-tone audiograms and speech recognition scores were used to select the ten best-hearing subjects among 50 volunteers over age 55. Randomizations of the stimuli were presented for labeling at intensity levels of 60 and 80 dB HL to this group and to ten normal-hearing volunteers under age 25. Results showed highly significant interactions of age with the temporal factors and with intensity: the older subjects required longer silence durations before reporting "rapid," especially for the shorter vowel durations and for the higher intensity level. These data suggest that age may affect the relative salience of different acoustic cues in speech perception, and that age-related hearing loss may involve deficits in the processing of temporal information, deficits that are not measured by standard audiometry.

Adolescent↗
PubMed2004

A positron emission tomography study of the neural basis of informational and energetic masking effects in speech perception.

Positron emission tomography (PET) was used to investigate the neural basis of the comprehension of speech in unmodulated noise ("energetic" masking, dominated by effects at the auditory periphery), and when presented with another speaker ("informational" masking, dominated by more central effects). Each type of signal was presented at four different signal-to-noise ratios (SNRs) (+3, 0, -3, -6 dB for the speech-in-speech, +6, +3, 0, -3 dB for the speech-in-noise), with listeners instructed to listen for meaning to the target speaker. Consistent with behavioral studies, there was SNR-dependent activation associated with the comprehension of speech in noise, with no SNR-dependent activity for the comprehension of speech-in-speech (at low or negative SNRs). There was, in addition, activation in bilateral superior temporal gyri which was associated with the informational masking condition. The extent to which this activation of classical "speech" areas of the temporal lobes might delineate the neural basis of the informational masking is considered, as is the relationship of these findings to the interfering effects of unattended speech and sound on more explicit working memory tasks. This study is a novel demonstration of candidate neural systems involved in the perception of speech in noisy environments, and of the processing of multiple speakers in the dorso-lateral temporal lobes.

Acoustic Stimulation↗
PubMed1992

A new portable sound processor for the University of Melbourne/Nucleus Limited multielectrode cochlear implant.

A new processor, called the spectral maxima sound processor (SMSP), has been developed for the University of Melbourne/Nucleus Limited multielectrode cochlear implant. The SMSP analyses sound signals by means of a bandpass filterbank having 16 channels which are allocated tonotopically to the implanted electrodes. Every 4 ms, typically, the six channels with the largest amplitudes are selected, and six corresponding electrodes are activated. In an ongoing study the performance of the SMSP is being compared with that of the Mini Speech Processor (MSP). Some results of speech perception tests from the first two SMSP users are presented, in which scores for the recognition of vowels, consonants, and words all showed significant increases over the corresponding MSP scores.

Cochlear Implants↗
PubMed1986

Vowel perception: experiments with a single-electrode cochlear implant.

We investigated vowel perception by 15 subjects using the single-electrode cochlear implant used at the House Ear Institute in Los Angeles. Subjects were postlingually deaf adults having histories of unsuccessful hearing aid use and a minimum of 6 to 12 months experience with the implant. Eleven American English vowels spoken by a male talker were tape recorded, digitized, analyzed, and controlled for the experiments. The stimuli were audio-recordings of both natural and loudness-matched vowels. Subjects rated the dissimilarity of both the naturally spoken and the loudness-matched vowels, and performed identification of the latter. Two normal-hearing subjects served as controls for the dissimilarity tasks. Multidimensional scaling, hierarchical clustering, and percent correct identification analyses were used to help determine the perceptual features used by the subjects in their judgments. Generally, the normal-hearing subjects took advantage of second formant (F2) frequency information. The cochlear-implant users relied primarily upon fundamental (F0) and first formant (F1) frequency information and demonstrated difficulty in vowel identification. No major differences were noted for the natural versus loudness-matched vowels. F2 information, requisite for accurate vowel recognition, did not correspond to any of the perceptual dimensions discerned in the results obtained from implant subjects.

Adult↗
PubMed1984

Postmasking effects of sensorineural tinnitus: a preliminary investigation.

In this study we provide some preliminary results of our attempt to measure the perception of tinnitus after the termination of a masker. The minimum level to mask tinnitus was determined for a 1-s masker in 10 subjects with sensorineural tinnitus. A continuous masker (parametrically varied in duration, frequency, and level) was then presented to the ear ipsilateral to the tinnitus. At the termination of the masker, subjects were required to press a button when their tinnitus "first returned" and a second button when it returned to "normal loudness." These response times were recorded automatically, and subjects reported what they heard after each trial. At low-level and short-duration maskers, the tinnitus typically was heard immediately after the masker termination. At higher levels and longer durations, different responses were observed. In two subjects, a silent interval was present after the masker, then the tinnitus returned at a softer loudness before returning to its premasker loudness. In one subject, the tinnitus was louder after the masker, and gradually returned to its premasker loudness. In another subject, the tinnitus returned immediately after the masker, but was softer than before. It then gradually increased to its premasker loudness. In the other two subjects, the tinnitus returned immediately to its normal loudness when the masker was terminated at all masker levels and durations. Higher level and longer duration maskers generally produced greater effects. Masker frequency, however, had little effect.

Adult↗
PubMed2001

Effects of degradation of intensity, time, or frequency content on speech intelligibility for normal-hearing and hearing-impaired listeners.

Many hearing-impaired listeners suffer from distorted auditory processing capabilities. This study examines which aspects of auditory coding (i.e., intensity, time, or frequency) are distorted and how this affects speech perception. The distortion-sensitivity model is used: The effect of distorted auditory coding of a speech signal is simulated by an artificial distortion, and the sensitivity of speech intelligibility to this artificial distortion is compared for normal-hearing and hearing-impaired listeners. Stimuli (speech plus noise) are wavelet coded using a complex sinusoidal carrier with a Gaussian envelope (1/4 octave bandwidth). Intensity information is distorted by multiplying the modulus of each wavelet coefficient by a random factor. Temporal and spectral information are distorted by randomly shifting the wavelet positions along the temporal or spectral axis, respectively. Measured were (1) detection thresholds for each type of distortion, and (2) speech-reception thresholds for various degrees of distortion. For spectral distortion, hearing-impaired listeners showed increased detection thresholds and were also less sensitive to the distortion with respect to speech perception. For intensity and temporal distortion, this was not observed. Results indicate that a distorted coding of spectral information may be an important factor underlying reduced speech intelligibility for the hearing impaired.

Adult↗
PubMed1994

Pitch perception in patients with a multi-channel cochlear implant using various pulses width.

Cochlear implants have been designed to partially restore hearing to those people who are totally deaf. Multi-channel cochlear implants offer the opportunity to evoke acoustic perceptions like loudness and pitch, elicited by a controllable pattern of electric stimulation by means of electrodes placed in different places along the cochlear length. In this study, two psychophysical experiments were conducted with 4 patients, 1 prelingually and 3 postlingually-deafened, implanted with the multi-channel cochlear prosthesis Nucleus 22. Experiments were carried out to study the effect of varying the width of the electric biphasic pulsatile stimuli on the discriminative abilities of the pitch perception. The tests involved place pitch ranking and pulse rate discrimination. Place pitch ranking was studied by determining the just noticeable difference in pitch pairs (jnd-pp), defined as the pair of nearest electrodes which elicit different pitch perception. Pulse rate discrimination was studied by determining the just noticeable difference in pulse rate (jnd-pr) defined as the minimal difference in stimulus repetition rate over a given electrode, which elicits different pitch perceptions. Both experiments were conducted using pulses of 400, 200, 100 and 50 microseconds/phase. The results indicated that in spite of the differences in pathologies and personal histories, both jnd-pp and jnd-pr decrease by diminishing the pulse width. Speech perceptual data, measured for various pulse widths, validates the usefulness of decreased pulse width which yields favorable results in the psychophysical tests.

Acoustic Stimulation↗