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PubMed1991

Activation of the human auditory cortex by speech sounds.

Magnetic evoked responses were recorded to different speech sounds in healthy humans. (i) Short words consisting of fricative consonant/vowel combinations evoked strong responses at the auditory cortex about 100 ms after the vowel onset. The response is specific to acoustic rather than phonetic aspects of the sounds. (ii) In a categorization task, words elicited a transient response followed by a sustained field (SF). When the subject counted the number of target words, SF was clearly increased. There were no consistent differences between the hemispheres and a similar increase of SF was observed when the subject classified the duration of two tones. (iii) When tone 'probes' were presented randomly to either ear and speech sounds to one ear, the 100-ms response was dampened and delayed bilaterally. The dampening was not specific to speech masking but dependent on the amount of frequency and amplitude transitions in the masker. All these experiments suggest that the auditory system performs a very similar analysis of both speech signals and other sounds. (iv) In a recent study, more closely related to speech perception, visual input from articulatory movements of the speaker was found to affect the activity of the auditory cortex. It seems that MEG studies can be useful in the study of brain mechanisms underlying speech perception in intact humans.

Acoustic Stimulation↗
PubMed1996

Loudness ratio production by cochlear implantees using the spectral maxima sound processor.

The loudness growth characteristics of five users of the Mini System 22 implant and the Spectral Maxima Sound Processor were measured and compared with those of five normally hearing subjects. The main objective was to evaluate the suitability of the function employed in the sound processor that converts acoustic input levels of electrical stimulation. The method of loudness ratio production was used. The average result of the normally hearing subjects for halving and doubling loudness was 10.8 dB. The results of three of the implantees were comparable with those of the normally hearing subjects (average 8.83 dB), while those of the remaining subjects were quantitatively and qualitatively different. Investigation showed that altering the amplitude conversion function in the sound processor would not make the results of these two implantees more like those of the other subjects. However, it is possible that their responses were affected by the limited input dynamic range of the sound processor.

Adult↗
PubMed1995

Measurement of variability in sound field audiometry due to subject movement.

Sound field audiometry is used primarily for hearing assessment in young children and for functional hearing aid evaluation. It is important that measurements are accurate and reliable as they affect the management of patients. Most clinics use a substitution method for calibration and, as a result, if the subject moves from the calibrated test point, the sound pressure level (SPL) at the ears will vary as the sound field is very rarely uniform. This variation can result in inaccurate threshold estimation and increased test-retest variability. A commonly used method for evaluating the potential errors due to subject movement involves measuring the variation in SPL, with respect to the test point, at six points around the test point. This method makes assumptions about the sound field which may not be valid and could lead to an underestimation of the variation present. The aim of this investigation was to assess the accuracy of this method. Measurements of variation were taken with a microphone and repeated with a head and torso simulator (HATS) which was used to represent a test subject. The total degree of variation indicated by these two methods was compared. The microphone measurements indicated less variation than the HATS measurements. The differences were statistically significant but small in clinical terms. Assuming that the HATS is properly representative of the normal population, then this result indicates that simple microphone measurements are acceptable for normal clinical practice but that higher quality measurements are desirable for critical work.

Audiometry↗
PubMed1995

An investigation into sound attenuation by earmould tubing.

A major problem in high-gain post-aural hearing aids is acoustic feedback. One of the sources of feedback is the plastic tubing that guides the sound from the hearing aid hook to the ear canal. The objectives of this study were to determine the effects of increases in tubing wall thickness on the amount of acoustic feedback in the hearing aid system and to characterize earmould tubing. Five different samples of Tygon tubing were tested, of which four had different wall thicknesses; the study also compared Tygon tubing with medical grade PVC tubing. Measurement of the wall thickness, taken from scanning electron micrographs, showed that the wall thickness differed from the National Association of Earmould Laboratories standard by less than 6% and was well within the manufacturer's tolerances. Measurement of sound attenuation showed that an increase in the tubing wall thickness of 0.330 mm (Tygon 13 Standard to Tygon 13 Double Wall) caused an increase in sound attenuation of 2 dB, across the frequency range measured (0.5-4 kHz). It was also found that the medical grade PVC had a 5 dB greater sound attenuation than the equivalent Tygon tubing. While these differences are quite small, they could contribute to a reduction in acoustic feedback when used in conjunction with other hearing aid or earmould improvements.

Acoustics↗
PubMed2005

Contrast sensitivity function of sound eye after occlusion therapy in the amblyopic children.

To verify the changes of mesopic and photopic contrast sensitivity function of sound eye whose visual acuity was kept the same after occlusion therapy in the amblyopic children. Fourteen sound eyes of amblyopic children (mean; 7.67 years; S.D., 1.50 years) who kept their visual acuity the same after the occlusion therapy were tested. The children had 6 hours of part-time patch therapy for 3 months prior to this examination. Among 14 amblyopic children, 8 were anisometric and 6 were strabismic amblyopes. Using the visual capacity analyzer which measures the minimal contrast level at from low to high spatial frequencies, the contrast sensitivity of sound eye was measured, under both photopic and mesopic condition, before and after 3 months of occlusion therapy. Comparing the contrast sensitivity of sound eye after the occlusion therapy to that before the occlusion, there was no statistical difference in photopic condition. When it comes to mesopic condition, the contrast sensitivity decreased at the intermediate spatial frequency level (3-13 c.p.d, p=0.028) after the occlusion therapy. The occlusion caused statistically significant decrease in mesopic contrast sensitivity, when the visual acuity was not changed after the occlusion therapy. It may indicate that mesopic contrast sensitivity can be considered as a useful tool for early detection of hidden occlusion amblyopia.

Amblyopia↗
PubMed1987

Influence of 12 hours of sound stimuli on gonad development and plasma luteinizing hormone in Japanese quail (Coturnix coturnix japonica) exposed to 6 hours of daily light.

Two experiments were conducted to determine the effects of sound stimulation on gonadal growth in male and female Japanese quail (Coturnix coturnix japonica) maintained under a photoperiod of 6 hr light and 18 hr dark (6L:18D) from 1 to 12 weeks of age (Experiment 1) or 1 to 14 weeks of age (Experiment 2). The quail were split into three sound environments as follows: 1) 12 hr of radio music (RS) beginning 1 hr before lights off; 2) 12 hr of vocalization from a breeding colony of quail (QV) beginning 1 hr before lights off; 3) no sound stimulation (NS). In Experiment 1, birds were killed at 8, 10, and 12 weeks of age and in Experiment 2, they were killed at 8, 10, 12, and 14 weeks of age. There were no significant differences in tests weights of the three groups at 8 and 10 wk of age (Experiment 1), but those of the RS and QV groups were larger (P less than or equal to .05) than those of the NS group at 12 weeks. Tests in the NS group appeared to grow between 8 and 10 weeks, then regress. There were no differences in testis weights at 8 and 10 weeks of age in Experiment 2. At 12 weeks, testes in the RS group were larger (P less than or equal to .05) than those of the other two groups and by 14 weeks testes of both sound stimulated groups were larger than the NS group and were also different from each other.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMed2003

Categorizing sounds by pitch: effects of stimulus similarity and response repetition.

Two experiments were performed to determine whether categorization of the pitch of a probe tone is influenced by the pitch of, and response made to, a preceding prime tone. The prime and the probe could be drawn either from a pool of low-frequency sounds or from a pool of high-frequency sounds. The results of both experiments indicated that the performance obtained was best when the prime and the probe were the same pitch (and therefore required the same response), intermediate when the two sounds differed in pitch and required different responses, and slowest when the prime and the probe differed in pitch but required the same response (i.e., they were drawn from the same frequency pool). The results of Experiment 2 revealed in addition that when a repeated response was required, performance declined as the magnitude of the frequency change increased and that responses were made more quickly and accurately if the direction of the frequency change was away from the alternative category than if it was toward the alternative category. The results demonstrate that categorization of sounds by pitch is accomplished with reference to a previous processing episode.

Audiometry, Pure-Tone↗
PubMedDate not supplied

Effect of multichannel digital signal processing on loudness comfort, sentence recognition, and sound quality.

This study evaluated the effect of increasing the number of processing channels from 32- to 64-signal processing channels on subjects' loudness comfort and satisfaction, sentence recognition, and sound quality of his or her own voice. Ten experienced hearing aid users with mild-to-moderate sensorineural hearing loss wore behind-the-ear (BTE) hearing aids with Adaptive Dynamic Range Optimization (ADRO) signal processing for a period of six weeks in the 32-channel and 64-channel conditions. Results revealed no significant differences in loudness comfort or satisfaction for the majority of sound samples as measured by the Subjective Loudness Test and Environmental Sounds Questionnaire. No significant differences in sentence recognition between the two processing conditions were found as measured by the Hearing In Noise Test (HINT). Additionally, no subjective differences in sound quality of subjects' own voice were determined by the Listening Tasks Questionnaire.

Aged↗
PubMed2006

Acceptable noise level: reliability measures and comparison to preference for background sounds.

The present study (1) assessed the reliability of the acceptable noise level (ANL) measure using speech-spectrum and speech-babble noises as the competing stimuli, and (2) investigated the relationship between ANL and preference for background sounds in 30 young adults with normal hearing sensitivity. Listeners were evaluated during three test sessions approximately one week apart. Results demonstrated that ANLs are highly reliable over short periods of time, independent of the background noise distraction. Mean ANLs, however, were affected by type of background noise distraction, indicating ANLs obtained using different competing stimuli should not be compared directly. Results further demonstrated that participants' ratings of preference for background sound were consistent over time; however, listeners' preference for background sound was not related to their acceptance of background noise (i.e., ANL). This may indicate listeners cannot accurately assess their ability to accept background sounds, at least with the questionnaire used in the present study.

Acoustic Stimulation↗
PubMed2004

[Difference in time of bowel sounds and passing of gas in abdominal hysterectomy patients having San-Yin-Jia (SP-6) acupressure].

PURPOSE: The purpose of this study was to compare differences in the time when bowel sounds were heard and gas was passed in women who had an abdominal hysterectomy and were treated for 5 minutes (experimental group A) or 10 minutes (experimental group B) with San-Yin-Jiao (SP-6) acupressure. METHOD: The design of this study was a nonequivalent control group non-synchronized post test only design. The participants included 142 women, 39 in experimental group A, 30 in experimental group B, and 73 in the control group. Data was collected using a structured questionnaire which included items on general characteristics and a self report of time when gas was passed. Differences for the three groups as to time when bowel sounds were heard and gas was passed were analyzed using ANOVA. RESULT: The time when bowel sounds were heard was statistically significantly shorter in both experimental groups compared to the control group(F=10.29, p=.000). The time when gas was passed was statistically significantly shorter in experimental group B(10 min) compared to the control group(F=4.68, p=.011). CONCLUSION: It could be concluded that SP-6 acupressure of 10 minutes was effective in shortening the time until bowel sounds were heard and gas was passed for women who had had an abdominal hysterectomy. Replication of the study with a larger number of participants is necessary in order to be able to generalize the results.

Acupressure↗
PubMed1999

Breeding soundness examination of North American bison bulls.

OBJECTIVE: To evaluate the breeding soundness examination procedure in plains bison bulls. DESIGN: Multiyear (1993 through 1997) cross-sectional clinical procedure evaluation. ANIMALS: Two hundred thirty-four 28- to 30-month-old bison bulls at Custer State Park. PROCEDURE: Breeding soundness examinations were performed on all bison bulls using 1992 Society for Theriogenology guidelines for beef cattle semen evaluation and reproductive tract examination. Linear and logistic regression analyses were used to detect correlations and associations among breeding soundness examination variables. RESULTS: Scrotal circumference (SC) was significantly correlated with body weight, percentage of normal spermatozoa, percentage of primary spermatozoal defects, and percentage of motile spermatozoa. Scrotal circumference was positively associated with increased odds of semen collection, satisfactory motility (> or = 30% motility), satisfactory morphology (> or = 70% normal spermatozoa), and simultaneous satisfactory motility and morphology. Receiver-operator characteristic curve analysis selected 29 cm as the optimal SC cutoff most predictive of simultaneous satisfactory spermatozoal motility and morphology. Only 36.2% (83/229) of the bison bulls had a SC of 29 cm or greater and satisfactory spermatozoal motility and morphology. CLINICAL IMPLICATIONS: SC is a good indicator of adequate spermatozoal motility and structure in bison. We recommend use of 30% spermatozoal motility, 70% normal spermatozoal morphology, and 29-cm SC as minimal satisfactory measurements for breeding soundness examinations of 28- to 30-month-old bison bulls that have been raised on forage-based nutrition.

Animals↗
PubMed1999

Noise-induced neurologic disturbances in divers exposed to intense water-borne sound: two case reports.

Divers may be exposed to intense noise underwater. Two cases of neurologic disturbances during experimental exposures to 15 min of continuous underwater sound are described. Sound exposure in the first case consisted of a warble tone with center frequency of 240 Hz and a sound pressure level of 160 dB re 1 microPa. Symptoms during exposure consisted of somnolence, lightheadedness, and an inability to concentrate. No apparent effect on hearing was noted. In the second case, a center frequency of 1,000 Hz at 181 dB was used. Lightheadedness, inability to concentrate, agitation, and head vibrations were noted during the exposure. The diver also exhibited a temporary auditory threshold shift of 19.2 dB. In both cases, overt symptoms resolved within 30 min after exposure, but both divers reported recurrent symptoms days to weeks after the exposures. Medical histories and examinations, assessment of dive profiles, and breathing gas analysis failed to support a source other than the sound exposures to account for the symptoms observed. Potential mechanisms for the described symptoms are discussed.

Adult↗
PubMedDate not supplied

[Using computer sound cards in electrophysiological data processing].

PC sound cards can be used for processing the data of bioelectric activity tests. The study of phenazepam effect upon the rat EEG showed that a PC sound card with the corresponding sound processing files can reveal the tranquilizer effects in EEG with the aid of standard analog-to-digital converters and bioelectric data processing routines. The obtained results show expediency of using the PC sound cards for the cerebral activity testing data processing.

Animals↗
PubMed1976

Effects of sound stimulus on gastric secretion and plasma corticosterone level in rats.

The effects of sound stimulus were studied on the gastric secretion in rats with chronically implanted cannulas. Attempts were made to correlate the changes in the secretion with those of the plasma corticosterone level. Exposure of the animals to sound stimulus (1 hr or 2 hr) produced a marked decrease in gastric secretion and a concomitant increase in plasma corticosterone. It appears that in producing these effects sound stimulus acted as a stressor. Furthermore, a paradoxical increase in secretion was noted in the first hour collection prior to the sound stimulus. This initial increase in secretion may be due to an adaptive compensatory mechanism in anticipation of its marked inhibition.

Acoustic Stimulation↗
PubMed1992

[Speech perception and otoacoustic emissions by pre-processing sound in the inner ear].

Direct observations of the basilar membrane movements show that sound perception can no longer be regarded as a passive process: vulnerable, energy-consuming amplification processes are required in the cochlea. The outer hair cells (OHC) fulfil this demand morphologically and functionally. These sensory cells have a double role: they perceive sound and thus modulate the cochlear biomechanics through their motile activity. The key event of sound transduction is performed by the inner hair cells (IHC) after active sound amplification in the OHC. The control of the OHC is assured by the efferent olivocochlear fibres which release acetylcholine (ACh) and gamma-aminobutyric acid (GABA) into the synaptic cleft at the basal pole of the OHC. Nicotinergic acetylcholine and GABA receptors within the outer cell membrane of OHC were identified and characterised. The application of the neurotransmitter GABA to the basal pole of vital OHC leads to a reversible elongation of the cylindrical cell body while ACh induces a reversible, slow contraction of the sensory cells. These two neurotransmitters are supposed to counteract in the control of the cochlear amplifier. The reciprocal distribution of ACh and GABA receptors and their counteracting function (contraction vs elongation) has an additional impact on the modulation of OHC function. The result is an even more diversified control of the cochlear amplifier. The energy-consuming cochlear amplifications are reflected by an epiphenomenon, i.e. the otoacoustic emissions (OAE). These are emitted by the cochlea and can be divided into "spontaneous OAE", "transitory evoked OAE" (TEOAE), "stimulus frequency OAE" and "distortion product OAE". The TEOAE are now an integrated part of audiological diagnosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Basilar Membrane↗
PubMed2003

Illusory sound perception in macaque monkeys.

In most natural listening environments, noise occludes objects of interest, and it would be beneficial for an organism to correctly identify those objects. When a sound of interest ("foreground" sound) is interrupted by a loud noise, subjects perceive the entire sound, even if the noise was intense enough to completely mask a part of it. This phenomenon can be exploited to create an illusion: when a silent gap is introduced into the foreground and high-intensity noise is superimposed into the gap, subjects report the foreground as continuing through the noise although that portion of the foreground was deleted. This phenomenon, referred to as auditory induction or amodal completion, is conceptually similar to visual induction, fill-in, illusory motion, and illusory contours. Two rhesus macaque monkeys performed a task designed to assess auditory induction. They were trained to discriminate complete stimuli from those containing a silent gap in the presence of two types of noise. Interrupting noise temporally coincided only with the gap, and in humans this causes induction. Surrounding noise temporally encompassed the entire foreground, and in humans this causes masking without auditory induction. Consistent with previous human psychophysical results, macaques showed better performance with surrounding masking noise than interrupting noise designed to elicit induction. These and other control experiments provide evidence that primates may share a general mechanism to perceptually complete missing sounds.

Acoustic Stimulation↗
PubMed2004

Computed tomography sound velocity reconstruction using incomplete data.

An approach based on limited-angle transmission tomography for reconstruction of the sound velocity distribution in the breast is proposed. The imaging setup is similar to that of x-ray mammography. With this setup, the time-of-flight data are acquired by a linear array positioned at the top of the compressed breast that both transmits and receives, and a metal plate is placed at the bottom as a reflector. The setup allows acoustic data acquisition for simultaneous B-mode image formation and the tomographic sound velocity reconstruction. In order to improve the sound velocity estimation accuracy, a new reconstruction algorithm based on a convex programming formulation has been developed. Extensive simulations for both imaging and time-of-flight data based on a 5-MHz linear array were performed on tissues with different geometries and acoustic parameters. Results show that the sound velocity error was generally 1-3 m/s, with a maximum of 5.8 m/s. The radii of the objects under investigation varied from 2 to 6 mm, and all of them were detected successfully. Thus, the proposed approach has been shown to be both feasible and accurate. The approach can be used to complement conventional B-mode imaging to further enhance the detection of breast cancer.

Algorithms↗
PubMed1991

Atrial sounds and endocardial electrograms recorded during coarse atrial fibrillation.

Hearing atrial sounds is unusual during atrial flutter and rare during atrial fibrillation. We report a patient with hypertrophic cardiomyopathy and coarse atrial fibrillation in whom atrial sounds were recorded phonocardiographically during endocardial atrial electrography. The atrial sounds were recorded phonocardiographically at the same periodicity as the atrial electrograms, and both had beat-to-beat variability in morphology, amplitude, and cycle length. These observations suggest that atrial sounds originate from the atrium and that organized electrical and mechanical activity occur in some types of atrial fibrillation.

Journal Article↗

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