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PubMed1995

Critical bandwidth determined by masking in the presence of two narrow-band noises.

In this experiment, the critical band (CB)-widths were measured using two narrow-band noises (NBNs) with steep cut-off slopes as a masker, varying their spectral level and center-frequency. The following results were obtained: (i) The CB-widths at all center-frequencies were narrower than the classical CB-widths estimated by Zwicker et al [J Acoust Soc Am 29:548-557 (1957)], and decreased continuously toward the lower frequency at the center-frequencies below 500 Hz, though Zwicker's data were constant in the same range. These results barely coincided with the frequency dependence of the equivalent rectangular bandwidth (ERB) which was estimated from the shape of the auditory filter measured directly. (ii) Level dependence of masking noise in CB was constant beyond 20 dB of the masked threshold. This depends on the use of NBN as a masker. (iii) The CB was influenced by distortion products and off-frequency listening. Accordingly, the bandwidths might differ with the experimental method.

Adult↗
PubMed1995

Relationship between psychophysical tuning curves and critical bandwidths.

In Experiment I, band noises were used as signals and pure tones were used as maskers. The conventional psychophysical tuning curves (PTCs) present the following characteristics depending on the signal level; slopes of the PTC are steeper than those of the auditory nerve fibers frequency threshold curve (FTC). This result from the large effect of the combination tones and, especially, of the off-frequency listening. Bandwidths of PTC do not depend on both signal levels and duration, but they are narrower than the equivalent rectangular bandwidth (ERB) of auditory filters. Masked thresholds at tips of PTC are affected by the temporal integration of signal sound at signal levels of 10- and 20-dB SL, but are not affected at 30-dB SL. This implies a close relation between PTCs and critical bandwidths (CB-widths). In Experiment II, pure tones were used as signals and band noise were used as maskers. The low- and high-frequency slopes were steeper in Experiment I. The flat parts of the masked threshold at the tips of curves become broader as the signal duration increased. No such flattening was found at a 30-dB signal level, irrespective of signal duration. The results of Experiment II coincide with the prediction derived from the excitation-pattern model. Masked thresholds at the tip of PTC were the same as in Experiment I. The conventional PTC represents the psychological frequency selectivity, and its 3-dB bandwidth corresponds to the CB-width. However, the quantitative properties depend greatly upon the bandwidths of the band noises used as signals or maskers.

Attention↗
PubMed1995

Psychophysical tuning curve and critical band determined by masking in the presence of FM sounds.

Frequency modulation (FM) sounds were used as simultaneous maskers to estimate the psychophysical tuning curve (PTC). Maskers (800 ms duration) were FM sounds sweeping upward (1.2-->2.8 kHz) in Experiment I and downward (2.8-->1.2 kHz) in Experiment II. The signal was a pure tone of 2 kHz and the signal levels were 15-, 20-, 30-, and 35-dB SL. Masked PTCs were obtained as a function of masker frequency. The results were as follows: (i) When an upward-sweeping FM sound is used for high signal level, the slope of the PTC is shallower on the low frequency side and steeper on the high frequency side, and the 10-dB bandwidth of PTC coincides with that of the restricted PTC. (ii) When a downward-sweeping FM sound is used for the high signal level, the above relation for the PTC slope is reversed, and the 10-dB bandwidth for PTC coincides with that of unrestricted PTC. (iii) PTCs determined by masking in the presence of FM sounds apparently restrict the subject to listening to off-frequency, and it is shown that the bandwidth of PTC properly reflects the critical band. (iv) The properties of these PTCs can be easily explained by a neural network model of lateral inhibition, so we can accept a hypothesis that the hierarchical processing mechanism is incorporated within the inferior colliculus for parallel signal processing. (v) We conclude that the frequency resolution and the critical band filtering are, therefore, realized in a psychophysically relevant way in the auditory midbrain level.

Adult↗
PubMed1990

Long-term effects of intense sound on hair cells of Corti's organ and endocochlear DC potential.

Cochleograms of guinea pig ears were made 30-40 days after exposure to intense pure tones of 300 Hz, 500 Hz, 2 kHz, or 4 kHz at 130-150 dB SPL for 4-24 h. At 4 kHz, hair cells in the basal turn disappeared totally, in the second turn moderately, and were relatively undamaged in the third and apical turns. At 500 Hz, hair cells in the second and third turns were almost completely injured and at 300 Hz moderately damaged in the third and apical turns although the basal turn remained undamaged. At 2 kHz for 9 h, hair cells were almost completely injured in all turns. Negative endocochlear DC potential (negative EP) induced by furosemide was observed in the basal turn but not in the third turn of animals exposed to 300 Hz. Contrarily, negative EP was observed in the third turn but not in the basal turn of animals exposed to 4 kHz. We conclude that the hair cells of Corti's organ play an essential role in the production of negative EP.

Acoustic Stimulation↗
PubMed1999

Acoustic assessment of voice signal deformation after partial surgery of the larynx.

OBJECTIVE: The main objective of the present study was to assess the degree of voice signal impairment among patients who had undergone partial surgery of the larynx due to cancer of this organ. Such on evaluation may be helpful in the selection of the optimal surgical technique for the treatment of tumors displaying a varying degree of local advancement. METHODS: A prospective examination was carried out among 128 patients. Additionally a comparative study of the control group consisting of 36 healthy males was carried out. Acoustic tests were carried out in an echo-free chamber. The temporal changes in the value of acoustic pressure of the uttered text were registered. The 'distance' between the normal speech signal and the pathological voice has been established. RESULTS: The values of the fundamental frequency increase together with an increase of the range of resection of anatomical structures. The biggest differences in the value of results describing the distance from the standard were observed after hemilaryngectomy. The shortest distance from the acoustic standard was observed after chordectomy. No significant differences in the degree of voice signal impairment among patients who had undergone extended chordectomy and hemilaryngectomy were observed. CONCLUSION: The above findings can be of help in arriving at an optimum solution in cases of partial surgery of the larynx. The problem is particularly important in situations where there is the choice between different types of surgery.

Adult↗
PubMed2000

Hearing loss and phacoemulsification.

PURPOSE: To determine the acoustic spectra of currently used phacoemulsification units and to contrast phacoemulsification-generated acoustic spectra with representative audiograms of common types of sensorineural hearing loss. SETTING: Mayo Clinic, Rochester, Minnesota, USA. METHODS: The acoustic spectra of 3 phacoemulsification systems (Alcon Series 20,000 Legacy, Storz Millennium, and AMO Diplomax) were recorded in an acoustically soundproofed room using a Roland VS-880 Digital Studio Workstation and analyzed with a Hewlett-Packard 35660A Dynamic Signal Analyzer. RESULTS: Phacoemulsification handpiece-generated harmonic overtones produced during ultrasound mode (6.0, 12.0, and 18.8 kHz for the 20,000 Legacy and Diplomax; 7.0 and 14.2 kHz for the Millennium) were outside the range of minimal decibel loss in individuals with hearing loss. Supplemental, low-frequency, console-generated tones produced during ultrasound mode (0.4 to 2.0 kHz for the Diplomax; 0. 1 to 1.5 kHz for the Millennium) were within the range of minimal decibel loss in individuals with hearing loss. CONCLUSION: Phacoemulsification systems with console-generated, low-frequency tones were audible to ophthalmologists with common types of sensorineural hearing loss.

Audiometry↗
PubMed2000

Comparing historical and contemporary opera singers with historical and contemporary Jewish cantors.

This study is an attempt to ascertain if singers from different traditions and milieus follow similar aesthetic trends regardless of training and/or background. Cantors who sang the Jewish synagogue liturgy during the Golden Age of cantorial singing prior to World War II came from Eastern and Central Europe. For the most part, they were not trained in the classical Western opera tradition. They received training from choir leaders and other cantors and the training was primarily in the modes of synagogue chant. Cantors today receive the same kinds of training that opera singers receive, often from the same teachers. Four groups of singers, consisting of four singers in each group, were utilized in this study. The four groups are: historical opera singers, contemporary opera singers, historical cantors, and contemporary cantors. The historical opera singer recordings date from as early as 1909 to as late as 1939. It was not possible to determine the dates of the historical cantor recordings. However, the four cantors chosen for this group were active only to the 1940s. Contemporary samples were taken from CDs and/or live recordings and all the singers from the contemporary groups are either still active or were active in the 1960s through the 1980s and all of them are considered to be premier-level singers in their respective areas. The variables analyzed were: vibrato pulse rate, frequency variation of the vibrato pulse above and below the mean sustained sung frequency in percent, the mean amplitude variation of the amplitude vibrato pulse above and below the mean sustained amplitude in percent and the fast Fourier transform (FFT) power spectrum of the sustained samples. Results indicate that most of the significant differences were found between eras and not between groups within a time period.

Humans↗
PubMed2000

The treatment of essential voice tremor with botulinum toxin A: a longitudinal case report.

The purpose of this study was to evaluate the effects of bilateral botulinum toxin injection into the thyroarytenoid (TA) muscles of a patient with essential voice tremor. Acoustic and aerodynamic data were collected weekly over a 16-week period. Flexible nasolaryngoscopy was performed prior to injection and 2, 6, 10, and 16 weeks postinjection. Perceptual analyses of the acoustic and nasolaryngoscopic data were performed. A reduction in frequency tremor and, to a lesser extent, amplitude tremor was observed during the 1-10 week period. Estimated laryngeal resistance decreased after injection and was accompanied in perceptual measures by a reduction in vocal effort, laryngeal tremor, and supraglottic hyperfunction. Essential voice tremor can be successfully attenuated with bilateral percutaneous injection of botulinum toxin A into the vocalis muscle.

Aged↗
PubMed2001

An investigation of a modal-falsetto register transition hypothesis using helox gas.

This study concerned the effect of the first subglottal formant (F1') on the modal-falsetto register transition in males and females. Phonations using air and a helium-oxygen mixture (helox) were used in a comparative study to tease apart possible acoustic and myoelastic contributions to involuntary register transitions. Recordings of the first subglottal formant and its accompanying bandwidths, and the lower and upper shift point marking the outer boundaries of abrupt register transitions, were obtained via a neck-mounted accelerometer, and analyzed using spectrograms and power spectra on a K-5500 Sona-Graph. The four subjects had their hearing masked bilaterally with speech level noise to increase the likelihood of involuntary register transition via minimized auditory feedback. In three of the four test subjects registration was surmised to be primarily a laryngeal event, as evidenced by the similar frequency dependency of voice breaks in both air and helox. It may be hypothesized that subglottal resonance influenced register transition in the fourth subject, as voice breaks rose with helox-induced phonation; however, this result did not reach statistical significance. Therefore, in this experiment subglottal resonance was not found to have a significant influence on register transition as originally hypothesized.

Adult↗
PubMed2001

Voice source characteristics in Mongolian "throat singing" studied with high-speed imaging technique, acoustic spectra, and inverse filtering.

Mongolian "throat singing" can be performed in different modes. In Mongolia, the bass-type is called Kargyraa. The voice source in bass-type throat singing was studied in one male singer. The subject alternated between modal voice and the throat singing mode. Vocal fold vibrations were observed with high-speed photography, using a computerized recording system. The spectral characteristics of the sound signal were analyzed. Kymographic image data were compared to the sound signal and flow inverse filtering data from the same singer were obtained on a separate occasion. It was found that the vocal folds vibrated at the same frequency throughout both modes of singing. During throat singing the ventricular folds vibrated with complete but short closures at half the frequency of the true vocal folds, covering every second vocal fold closure. Kymographic data confirmed the findings. The spectrum contained added subharmonics compared to modal voice. In the inverse filtered signal the amplitude of every second airflow pulse was considerably lowered. The ventricular folds appeared to modulate the sound by reducing the glottal flow of every other vocal fold vibratory cycle.

Culture↗
PubMed2001

Acoustic analysis of voice quality with or without false vocal fold displacement after cordectomy.

Conventional cordectomy by means of a laryngofissure is one of the therapeutic options for treatment of early glottic cancer. To improve the poor voice quality related to this kind of operation, many authors have developed different techniques to repair the mucosal defect. We analyzed voice quality acoustically and compared it after cordectomy alone and after cordectomy with the reconstruction of the vocal cord in a group of 14 patients affected by T1 glottic carcinoma. All the patients underwent postoperative speech therapy. Three patients who underwent cordectomy with reconstruction showed the presence of diplophonia, while two patients without reconstruction showed the presence of bitonality. The differences of the acoustic parameters (jitter, shimmer, harmonic-to-noise ratio) between the two groups of patients were not statistically significant. Reconstruction of the vocal cord does not seem to improve voice quality after cordectomy even in combination with postoperative speech therapy.

Aged↗
PubMed2001

Devising an objective nasal vibration test for nasal resonatory disorders.

The present study investigates the clinical applicability of a new device, which objectively measured nasal resonating vibration via piezoelectric vibratory sensor in 10 normal volunteers, 10 patients with definite hypernasality, and 10 nasal polyposis patients. For the assessment of the hypernasality, the ratio of /ng/ to /a/ as well as the ratio of /mama/ to /papa/ passages were used. For the evaluation of hyponasality, the ratio of nasal vibration postinduced to preinduced cul-de-sac resonation was calculated. The control group showed the ratio of /ng/ to /a/ and /mama/ to /papa/ passages to be larger than 8, whereas the ratio was markedly lower in the hypernasality group. The vibratory signals of /a/ and /ng/ increased markedly in the control and the hypernasality groups after inducing cul-de-sac resonation, but the change was minimal in the hyponasality group. This new device could detect nasal resonatory disorders and readily differentiate between hypernasality and hyponasality.

Humans↗
PubMed2001

Deviant vocal fold vibration as observed during videokymography: the effect on voice quality.

Videokymographic images of deviant or irregular vocal fold vibration, including diplophonia, the transition from falsetto to modal voice, irregular vibration onset and offset, and phonation following partial laryngectomy were compared with the synchronously recorded acoustic speech signals. A clear relation was shown between videokymographic image sequences and acoustic speech signals, and the effect of irregular or incomplete vocal fold vibration patterns was recognized in the amount of perceived breathiness and roughness and by the harmonics-to-noise ratio in the speech signal. Mechanisms causing roughness are the presence of mucus, phase differences between the left and right vocal fold, and short-term frequency and amplitude modulation. It can be concluded that the use of simultaneously recorded videokymographic image sequences and speech signals contributes to the understanding of the effect of irregular vocal fold vibration on voice quality.

Aged↗
PubMed2001

Vocal tract resonance analysis of aging voice using long-term average spectra.

This study is the first to use long-term average spectra (LTAS) to investigate resonance characteristics of dynamic speech in young adulthood and old age. A total of 80 speakers participated, divided equally by age group and gender. All elderly speakers were healthy, active members of the community. Measurement of the first three spectral peaks in LTAS from the first paragraph of the Rainbow Passage revealed significant lowering of peak 1 from young adulthood to old age in both men and women. Peaks 2 and 3 also lowered significantly across the adult lifespan in women and showed a tendency to lower in men. These acoustic findings are consistent with anatomic data suggesting that aging results in lengthening of the supraglottic vocal tract. Findings that women demonstrate more substantial lowering of spectral peaks with aging than men suggest that women may undergo more pronounced age-related lengthening of the supraglottic vocal tract. Alternatively, it is possible that elderly men systematically alter tongue position during vowel articulation while elderly women are less inclined to do so. Taken in conjunction with previous research, these findings suggest a "mixed model" of vocal tract resonance changes with aging in which an interaction exists between gender, the resonance effects of laryngeal lowering, and vowel articulatory patterns.

Adult↗
PubMed2001

Comparison of singer's formant, speaker's ring, and LTA spectrum among classical singers and untrained normal speakers.

Many studies have described and analyzed the singer's formant. A similar phenomenon produced by trained speakers led some authors to examine the speaker's ring. If we consider these phenomena as resonance effects associated with vocal tract adjustments and training, can we hypothesize that trained singers can carry over their singing formant ability into speech, also obtaining a speaker's ring? Can we find similar differences for energy distribution in continuous speech? Forty classically trained singers and forty untrained normal speakers performed an all-voiced reading task and produced a sample of a sustained spoken vowel /a/. The singers were also requested to perform a sustained sung vowel /a/ at a comfortable pitch. The reading was analyzed by the long-term average spectrum (LTAS) method. The sustained vowels were analyzed through power spectrum analysis. The data suggest that singers show more energy concentration in the singer's formant/speaker's ring region in both sung and spoken vowels. The singers' spoken vowel energy in the speaker's ring area was found to be significantly larger than that of the untrained speakers. The LTAS showed similar findings suggesting that those differences also occur in continuous speech. This finding supports the value of further research on the effect of singing training on the resonance of the speaking voice.

Adult↗
PubMed2001

Soft phonation in the male singing voice: a preliminary study.

Sustained high notes, diminishing gradually from the loudest to the softest phonation within a maneuver called messa di voce, are examined in two contrasting professional tenor voices. Signals of the sound pressure level, electroglottograph, and mean esophageal pressure are recorded, and similar maneuvers by the same subjects are examined stroboscopically. The lyric voice is found to make a gradual diminuendo while maintaining nearly constant posture of the vocal tract together with a phase of complete closure in the glottal cycle. The robust voice, by contrast, passes abruptly from a production of high subglottal pressure and a high closed quotient to one of low pressure and incomplete closure, and the transition is marked by a sudden opening of the previously constricted laryngeal collar. It is proposed that the mode of soft voice production demonstrated by the robust voice be recognized as a distinct register of the singing voice.

Electromyography↗
PubMed2002

A comparison of two methods of formant frequency estimation for high-pitched voices.

This study sought to compare formant frequencies estimated from natural phonation to those estimated using two methods of artificial laryngeal stimulation: (1) stimulation of the vocal tract using an artificial larynx placed on the neck and (2) stimulation of the vocal tract using an artificial larynx with an attached tube placed in the oral cavity. Twenty males between the ages of 18 and 45 performed the following three tasks on the vowels /a/ and /i/: (1) 4 seconds of sustained vowel, (2) 2 seconds of sustained vowel followed by 2 seconds of artificial phonation via a neck placement, and (3) 4 seconds of sustained vowel, the last two of which were accompanied by artificial phonation via an oral placement. Frequencies for formants 1-4 were measured for each task at second 1 and second 3 using linear predictive coding. These measures were compared across second 1 and second 3, as well as across all three tasks. Neither of the methods of artificial laryngeal stimulation tested in this study yielded formant frequency estimates that consistently agreed with those obtained from natural phonation for both vowels and all formants. However, when estimating mean formant frequency data for samples of large N, each of the methods agreed with mean estimations obtained from natural phonation for specific vowels and formants. The greatest agreement was found for a neck placement of the artificial larynx on the vowel /a/.

Adolescent↗
PubMed2002

Cancellation of simulated environmental noise as a tool for measuring vocal performance during noise exposure.

It can be difficult for the voice clinician to observe or measure how a patient uses his voice in a noisy environment. We consider here a novel method for obtaining this information in the laboratory. Worksite noise and filtered white noise were reproduced over high-fidelity loudspeakers. In this noise, 11 subjects read an instructional text of 1.5 to 2 minutes duration, as if addressing a group of people. Using channel estimation techniques, the site noise was suppressed from the recording, and the voice signal alone was recovered. The attainable noise rejection is limited only by the precision of the experimental setup, which includes the need for the subject to remain still so as not to perturb the estimated acoustic channel. This feasibility study, with 7 female and 4 male subjects, showed that small displacements of the speaker's body, even breathing, impose a practical limit on the attainable noise rejection. The noise rejection was typically 30 dB and maximally 40 dB down over the entire voice spectrum. Recordings thus processed were clean enough to permit voice analysis with the long-time average spectrum and the computerized phonetogram. The effects of site noise on voice sound pressure level, fundamental frequency, long-term average spectrum centroid, phonetogram area, and phonation time were much as expected, but with some interesting differences between females and males.

Acoustic Stimulation↗