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At least 1,711 records · Page 95Linked to original sources
PubMed2000

Adaptation to loudness and environmental stimuli in three newly fitted hearing aid users.

Hearing aid fitting strategies can be categorized according to whether a loudness normalization or a loudness equalization rationale is employed. Regardless of the underlying rationale, the amount of patient participation in determining the initial hearing aid settings will vary when an audiologist-driven (AD) versus a patient-driven protocol is employed. When an AD protocol is used, few changes are made during the initial fitting session based on user feedback. It is assumed that the patient will adapt to the loudness and/or sound quality provided by the hearing aids if not immediately acceptable. The following three case reports document varying degrees of adaptation to hearing aid settings derived using an AD approach. Clinical implications will be discussed.

Adaptation, Physiological↗
PubMed1999

A model of frequency coding in the central auditory nervous system.

A phenomenological model for neural coding in the central auditory system is presented. This model is based on average rate-place codes and the hypothesis is that the rate-place code present in the population of low spontaneous rate nerve fibres is adequate to account for frequency discrimination thresholds across the entire audible frequency range. The activity of a population of nerve fibres in response to an input pure tone is calculated and a neural spike train pattern is generated. An optimal central observer estimates the input frequency from the spike train pattern. The model output is the frequency difference limen at the specific input frequency, determined from the estimated input frequency. It is shown that a rate-place code can account for psychoacoustically observed frequency difference limens. The model also supports the hypothesis that a human listener does not make full use of all the information relevant to frequency that is available in auditory nerve spike trains.

Auditory Cortex↗
PubMedDate not supplied

Effect of hearing loss, centre frequency, and bandwidth on the shape of loudness functions in categorical loudness scaling.

Loudness functions of narrow-band and broad-band stimuli were measured with eight normally-hearing and eight hearing-impaired listeners using a categorical loudness scaling method. In the normally-hearing listeners, narrow-band stimuli, generally generated loudness functions whose slope increased with increasing level, whereas broad-band stimuli generated more linear loudness functions. These differences can be explained by the level dependence of spectral loudness summation, which is known to be most prominent at moderate levels. In the hearing-impaired listeners, the narrow-band loudness functions generally showed a more linear shape than in the normally-hearing listeners. A consequence of these findings might be that the optimal shape of the input/output curve of a hearing aid is affected not only by the signal power in the respective frequency channels but also by the bandwidth of the input signal. However, there were considerable differences between listeners in both groups regarding the individual shape and absolute position of the loudness functions. Therefore, no normative reference could be extracted that would allow for a quantification of the bandwidth effect on an individual basis.

Adult↗
PubMed2001

Inhibition of pericranial muscle activity, respiration, and heart rate enhances auditory sensitivity.

We investigated whether previously observed inhibition of pericranial electromyographic (EMG) activity, respiration, and heart rate during sensory intake processes improves auditory sensitivity. Participants had to detect weak auditory stimuli. We found that EMG activity in masticatory and lower facial muscles, respiration, and heart rate were more strongly inhibited when stimulus intensity was gradually lowered to threshold level whereas EMG of upper facial muscles progressively increased. Detection of near-threshold stimuli was inversely related to prestimulus EMG levels in masticatory and lower facial muscles. In two additional experiments, it was investigated whether steady, voluntary contractions negatively influence auditory sensitivity. As expected, contraction of zygomaticus produced an increase in auditory threshold in comparison with contraction of corrugator or first dorsal interosseus. It is concluded that attention to external stimuli is accompanied by quieting of those somatic activities that produce internal noise or are accompanied by impaired middle ear transmission of auditory stimuli.

Adolescent↗
PubMed2001

Interactive effects of low-pass filtering and masking noise on word recognition.

A word recognition in noise paradigm was employed to examine temporal resolution in individuals with simulated hearing loss. Word recognition scores were obtained for low-pass filtered speech (i.e., cutoff frequencies of 1000,1250, and 1500 Hz) presented in continuous and interrupted noise at signal-to-noise ratios (SNRs) of -10, 0, and 10 dB. Performance improved with increasing SNR and low-pass frequency filter settings. Generally, word recognition performance was better in the interrupted noise condition than the continuous noise condition. This effect was greatest in the -10 dB SNR condition. Since the continuous/interrupted performance difference steadily declined as a function of low-pass filter cutoff frequency, these findings suggest that one factor leading to poorer speech recognition in individuals with high-frequency hearing impairment may be their dependence on low-frequency hearing channels that are inherently poorer than high-frequency channels for temporal resolution.

Adult↗
PubMed2001

Effect of spectral shaping and content on loudness discomfort.

The purpose of this investigation was to study the impact of spectral shape and content on thresholds of discomfort (TD) for listeners with normal hearing and listeners with hearing loss. Secondary to that purpose was to quantify binaural summation at high intensities across complex stimulus conditions for both groups of listeners. Forty subjects (20 with normal hearing, 20 with hearing loss) participated. Complex acoustic stimuli (multitone and continuous discourse) were filtered to have four spectral shapes: (1) flat spectrum, (2) long-term average speech spectrum, (3) reverse long-term average speech spectrum, and (4) the TD contour derived for each subject from pure-tone TD obtained with eight pure tones from 250 to 4000 Hz. The results suggest that (1) TD for complex stimuli are lower for subjects with hearing loss compared with those with normal hearing, suggesting increased loudness summation with this population; (2) binaural summation of approximately 6 dB (independent of stimulus type, filter shape, or spectral content), indicating that a correction of similar magnitude for bilateral hearing aid fittings is appropriate; and (3) TD obtained at 750, 1500, and 3000 Hz accounted for approximately 60 percent of the variance in the complex TD measures, suggesting that TD at these frequencies be used to set the output obtained from a hearing aid with a 90-dB pure-tone sweep as the input stimulus.

Adult↗
PubMed2002

From spectrum to space: the contribution of level difference cues to spatial receptive fields in the barn owl inferior colliculus.

Space-specific neurons in the owl's inferior colliculus have spatial receptive fields (RFs) computed from interaural time (ITD) and level (ILD) differences. Because of the shape of the owl's head, these cues vary with frequency in a manner specific for each location. We sought to determine the contribution of ILD to spatial selectivity. We measured the normal spatial receptive fields of space-specific neurons using virtual sound sources (i.e., noises filtered to simulate external sound sources, presented using headphones). The virtual-source filters were then altered so that ITD was fixed while frequency-specific ILDs varied according to location in the usual manner. The resulting "ILD-alone" RF typically revealed a horizontal band of excitation that included the normal RF. Above and below, the neurons were inhibited. Interestingly, the maxima of ILD-alone RFs were generally outside the normal RF, suggesting that space-specific neurons are not optimally tuned to the ILD spectrum occurring at the normal RF location. Congruously, frequency-specific ILD tuning, assessed with tones, better matched the ILDs at the peak of the ILD-alone RF than those at the peak of the normal RF. The firing evoked from the normal RF may thus reflect the balance of excitatory and inhibitory inputs needed to appropriately restrict the receptive field. Frequency-specific ILD tuning curves were combined with measured head-filtering characteristics to predict responses to the frequency-specific ILDs at each location. The predicted ILD-alone RFs, which are based on a simple sum of frequency-specific inputs, accounted for 56% of the variance in our measured ILD-alone RFs.

Acoustic Stimulation↗
PubMed2002

[Sensitivity of the neurons in the auditory inferior colliculus of mice to the direction of the shift of broadband spectral notch noise].

Series of a notch noise with regular shifts of the notch center frequency: one--from low frequencies to high frequencies and the other--from high frequencies to the low, were synthesized. The notch noise series imitated sound source vertical moving. Single neuron's responses of inferior colliculus of the house mouse (Mus musculus) to the notch-noises altered with notch central frequency varying through excitatory and inhibitory frequency response areas in neurones' receptive fields. The neural responses alteration to the notch noise varying depended on the bandwidth of notch. Disinhibition in inhibitory side band could be higher if the notch overlying the inhibitory areas followed the notch overlying the excitatory areas. The data obtained make it possible to consider the excitatory and inhibitory interaction as a mechanism of neural sensitivity to the notch moving direction. Neurones' response set could provide information about sound source moving over auditory space.

Acoustic Stimulation↗
PubMedDate not supplied

The sound exposure of the audience at a music festival.

During the Paleo Festival in Nyon, Switzerland, which took place from 24th to 29th July 2001, ten volunteers were equipped each evening with small sound level meters which continuously monitored their sound exposure as they circulated among the various festival events. Sound levels at the mixing console and at the place where people are most heavily exposed (in front of the speakers) were measured simultaneously. In addition, a sample of 601 people from the audience were interviewed over the six days of the festival and asked their opinion of sound level and quality, as well as provide details of where in the arena they preferred to listen to the concerts, whether they used ear plugs, if they had experienced any tinnitus, and if so how long it had persisted. The individual sound exposure during a typical evening was on average 95 dB(A) although 8% of the volunteers were exposed to sound levels higher then 100 dB(A). Only 5% of the audience wore ear plugs throughout the concert while 34% used them occasionally. While some 36% of the people interviewed reported that they had experienced tinnitus after listening to loud music, the majority found both the music quality and the sound level good. The sound level limit of 100 dB(A) at the place where the people are most heavily exposed seems to be a good compromise between the public heath issue, the demands of artists and organisers, and the expectations of the public. However, considering the average sound levels to which the public are exposed during a single evening, it is recommended that ear plugs be used by concert-goers who attend more than one day of the festival.

Adolescent↗
PubMed2003

[Otoacoustic emissions in sudden deafness].

UNLABELLED: The idiopathic type of sudden deafness installed in few hours become evident in audiometry as deafness perceptive of loud tones, neurosensorial deafness of loud tones and completely of treble sounds or cofosis. The otoacoustic emissions are modificated in sudden deafness. OBJECTIVES: To know and describe how are the otoacoustic emissions and the audition in sudden deafness. To analyse a possible relationship between audition, otovestibular and clinic participation with the parameters of the graphoelements of the otoacoustic emissions. PATIENTS AND METHODS: We study 52 patients with diagnostic of sudden deafness with a backward, observational and descriptive and analytic design of the results. Patients with ORL diagnostic were selectioned and audiometric, vestibular test and otoacoustic emissions were made. RESULTS: In our research we find quantitative and qualitative variations statistically significative in the otoacoustic emissions design. Its presence in the different frequencies is altered or is missing in any case of sudden deafness in which there are damages of the inner ear. There is not associative correlation between the alterations of otoacoustic emissions and the kind of sudden deafness, neither its provoking factors, anigiohematical, viral or traumatic. DISCUSSION AND CONCLUSIONS: There are modifications of the otoacoustic emissions but not specificals or the kinds of sudden deafness and its provoking factors. Another publications agree and underwrite our discoveries. We thought that our aportation with this study is fundamental for the clinic application of the otoacoustic emissions in the processes of sudden deafness.

Adult↗
PubMed1992

[Dependence of 'audio-phonatoric coupling' of speech rate and speech loudness].

The 'audio-phonatoric coupling' (APC) was investigated in two independent experiments. Slightly delayed auditory feedback (delay time 40 ms) of the subjects' own speech was used as experimental method. The first experiment was conducted to examine whether the strength of the APC depends on the speech rate. In this experiment 16 male Subjects (Ss) were required to utter the testword/tatatas/either with stress placing on the first or second syllable at two different speech rates (fast and slow). In 16% of the randomly chosen speech trials, the delayed auditory feedback (DAF; 40 ms delay) was introduced. It could be shown that the stressed phonation was significantly lengthened under the DAF condition. This lengthening was greater when Ss spoke slowly. The unstressed phonations were not influenced by the DAF condition. The second experiment was conducted to examine whether or not speech intensity effects APC. Nine male Ss were required to utter the testword/tatatas/either with stress placing on the first or second syllable using three different speech intensities (30 dB, 50 dB and 70 dB). In 16% of the randomly chosen speech trials DAF condition was introduced. It could be shown that speech intensity does not influence the DAF effect (lengthening of stressed phonation). These findings were taken as evidence that the auditory feedback of the subjects' own speech can be incorporated into speech control during ongoing speech. Obviously, this feedback information is efficient only during the production of stressed syllables, and varies as a function of speech rate. In addition, the significance of stressed syllables for the structuring of speech is discussed.

Adult↗
PubMed2003

[Dependence of the mouse inferior colliculus neurons activity on position and direction of movement of the spectral contrast].

Response variability of the single neurons of the inferior colliculus of mouse (Mus musculus) to series of noise bands and of notch noises with regular 1/12 octave steps of the band/notch center frequency and width of noise band/notch 1/3 octave, was studied. Neurons with strong inhibitory influence in excitatory response area (inhibitory-dominated) show low impulse activity when noise band exceeded excitatory response area. Spectral contrasts crossing the center of excitatory response area (at CF or nearly CF) were found to be the most efficient stimuli for such neurons. Neuron responses to spectral contrasts derived both from noise band and noise notch were identical. Approaching of inhibitory and excitatory inputs is expected to sharpen the auditory neurons frequency tuning to position of spectral contrasts, similar to neuronal processing in visual system. Neuron selectivity to the direction of spectral contrasts movement was determined in neuron response differences when the noise band or notch shifted from excitatory area to inhibitory areas as compared with shift in the opposite direction. Functional role of contrast mechanism for sound localization on the base spectral cues related to external ear transfer characteristics is discussed.

Acoustic Stimulation↗
PubMed2003

GABAergic inhibition and the effect of sound direction on rate-intensity functions of inferior collicular neurons of the big brown Bat, Eptesicus fuscus.

GABAergic inhibition shapes many auditory response properties of neurons in the inferior colliculus of the big brown bat, Eptesicus fuscus. This study examined the role of GABAergic inhibition on direction-dependent rate-intensity functions of bat inferior collicular neurons. When plotted at three sound directions (60 degrees contralateral, 0 degrees and 60 degrees ipsilateral relative to recording site), most collicular neurons had nonmonotonic and saturated rate-intensity functions at 60 degrees contralateral and 0 degrees but had monotonic rate-intensity functions at 60 degrees ipsilateral. The dynamic range of rate-intensity functions of majority (>90%) of collicular neurons significantly decreased as the sound direction changed from 60 degrees contralateral to 60 degrees ipsilateral. Bicuculline application increased or decreased the dynamic range of IC neurons in different degrees with sound direction and abolished direction-dependent intensity sensitivity of these IC neurons. Possible mechanisms for these observations are discussed.

Animals↗
PubMed2003

Masking effect of music upon oral information processing.

The masking effect of three types of music and white masking noise upon special audiometric tests was determined in laboratory c. The stimulus-noise (S/N) ratio was found to be the most considerable factor influencing oral information processing in spite of the type of music or noise used as a masking agent. All types of music (modern, classic or modern music records in backwards order) showed no significant differences in masking being in the same way stronger maskers as white noise. Some conclusions are made concerning hygienic and ergonomic aspects of the problem.

Audiometry, Speech↗
PubMed1992

Effects of radiation on hearing in patients with malignancies of head and neck.

Patients with normal hearing at the start of radiation were tested for hearing during (30 GY) and at the end of radiation therapy (45-60 GY) in order to determine if there was any alteration in their pure tone hearing thresholds. A significant increase in the hearing threshold was found at high frequencies at the end of therapy. At the end of the course of radiation, clinical findings suggestive of middle ear changes due to radiation were seen in 33% of the ears. Patients whose ears are included in the field of radiation may have to be forewarned to expect a loss in their acuity of hearing, especially those whose professional life may depend on it.

Adolescent↗