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PubMed2005

Decline of speech understanding and auditory thresholds in the elderly.

A group of 29 elderly subjects between 60.0 and 83.7 years of age at the beginning of the study, and whose hearing loss was not greater than moderate, was tested twice, an average of 5.27 years apart. The tests measured pure-tone thresholds, word recognition in quiet, and understanding of speech with various types of distortion (low-pass filtering, time compression) or interference (single speaker, babble noise, reverberation). Performance declined consistently and significantly between the two testing phases. In addition, the variability of speech understanding measures increased significantly between testing phases, though the variability of audiometric measurements did not. A right-ear superiority was observed but this lateral asymmetry did not increase between testing phases. Comparison of the elderly subjects with a group of young subjects with normal hearing shows that the decline of speech understanding measures accelerated significantly relative to the decline in audiometric measures in the seventh to ninth decades of life. On the assumption that speech understanding depends linearly on age and audiometric variables, there is evidence that this linear relationship changes with age, suggesting that not only the accuracy but also the nature of speech understanding evolves with age.

Acoustic Stimulation↗
PubMed2000

Auditory thresholds in a sound-producing electric fish (Pollimyrus): behavioral measurements of sensitivity to tones and click trains.

In this report we present the first behavioral measurements of auditory sensitivity for Pollimyrus adspersus. Pollimyrus is an electric fish (Mormyridae) that uses both electric and acoustic signals for communication. Tone detection was assessed from the fish's electric organ discharge rate. Suprathreshold tones usually evoked an accelerated rate in naive animals. This response (rate modulation > or =25%) was maintained in a classical conditioning paradigm by presenting a weak electric current near the offset of 3.5-s tone bursts. An adaptive staircase procedure was used to find detection thresholds at frequencies between 100 and 1700 Hz. The mean audiogram from six individuals revealed high sensitivity in the 200-900 Hz range, with the best thresholds near 500 Hz (66.5+/-4.2 SE dB re: 1 microPa). Sensitivity declined slowly (about 20 dB/octave) above and below this sensitivity maximum. Sensitivity fell off rapidly above 1 kHz (about 60 dB/octave) and no responses were observed at 5 kHz. This behavioral sensitivity matched closely the spectral content of the sounds that this species produced during courtship. Experiments with click trains showed that sensitivity (about 83-dB peak) was independent of inter-click-interval, within the 10-100 ms range.

Acoustic Stimulation↗
PubMed2005

Delayed-onset temporary auditory threshold shift following head blow in guinea pigs.

This study attempts to investigate the development of sensorineural hearing loss following a head blow without skull fracture in association with physiological and histopathologic changes in an experimental animal model. With the head in a freely movable position, albino guinea pigs were given a single blow to the occipital region by a head blow device. At 1, 7, and 14 days after the blow, the animals' auditory brainstem response (ABR) and cochlear microphonics (CM) were examined, and both the temporal bone and brain stem were observed by light and electron microscopy. The ABR threshold was unchanged at day 1, was significantly increased at day 7, and was fully recovered at day 14. The I-V and I-II interpeak latencies were significantly prolonged at days 1 and 7, and wave I latency was significantly prolonged at day 7 only. These latencies were recovered to normal limits at day 14. On the other hand, no significant change in CM versus the control group was observed at any point in the measurements. Histopathologically, no abnormal finding was seen at the light microscopic level. However, at the electron microscopic level, there were some injuries to the eighth nerve. At day 1, the lamellar structure of the myelin sheath was irregular, and the periaxonal space was expanded; at day 7, the myelin sheath was disintegrated. At day 14, however, these changes were partially reversed. These results suggest that sensorineural hearing loss following a head blow in this model is attributed to dysfunction of the eighth nerve rather than to cochlear impairment.

Animals↗
PubMed1988

Low-frequency auditory brainstem response threshold.

Auditory brainstem thresholds have been determined in 35 non-cooperative, anaesthetized children using a 'two-point audiogram' paradigm. The high-frequency point was found with a 2 kHz tone-burst without masking, and the low-frequency with a 0.5 kHz tone-burst together with 1 kHz high-pass noise masking. Great variability was found in the low-frequency thresholds, and only 3 of 18 ears with normal high-frequency thresholds had low-frequency thresholds below 70 dB nHL. It is concluded that the 0.5 kHz tone-burst with 1 kHz high-pass noise masking is not a reliable method for routine assessment of low-frequency auditory threshold at the brainstem level.

Adolescent↗
PubMed1993

Cortical evoked potential criteria in the objective assessment of auditory threshold: a comparison of noise induced hearing loss with Ménière's disease.

Amplitude of the N1 component of the cortical response was used to objectively determine threshold of hearing at 1 kHz and 4 kHz in a series of consecutively referred medicolegal cases with alleged occupational noise induced hearing loss and a control group of patients with Ménière's disease who were not seeking compensation for their hearing loss. The cortical response thresholds were compared with the subjective pure tone audiometric (PTA) thresholds at the same frequencies. The cortical and PTA thresholds were 'within 10 dB' for 84 and 92 per cent of the cases of noise induced hearing loss (NIHL) and Ménière's disease respectively, confirming the validity of CERA as a means of defining accurately the frequency specific thresholds and the audiometric configuration. Of the remaining 16 per cent of NIHL, 13 per cent exaggerated their PTA thresholds at 1 kHz and 10 per cent at 4 kHz whilst the error in cortical threshold estimation was beyond the 10 dB level for three and six per cent of cases at those frequencies respectively. The median exaggeration of threshold was 25 dB. For eight per cent of the Ménière's patients, thresholds exceeded 10 dB at both 1 and 4 kHz, four per cent of whom exaggerated their PTA thresholds and four per cent had a test error greater than 10 dB. A similar percentage (four per cent) of both groups revealed a cortical test error greater than 10 dB whereas three times as many cases of noise induced hearing loss (13 per cent) revealed exaggeration of their subjective audiometric thresholds compared with the Ménière's group (four per cent).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

[Measurement of the temporary auditory threshold shift (TTS) for evaluation of the degree of noise hazard].

Long-term investigations of noise in coal mines enhanced the need to take measurements at work stations posing high risk of methane explosion. To facilitate evaluation of noise hazard at the workplace in coal mines, attempts have been made to apply TTS measurements. Measurements of TTS taken within 3 to 5 minutes after cessation of noise exposure in industrial conditions made it possible to evaluate equivalent sound level.

Adult↗
PubMed2005

Comparisons between neural response imaging thresholds, electrically evoked auditory reflex thresholds and most comfortable loudness levels in CII bionic ear users with HiResolution sound processing strategies.

CONCLUSIONS: The data collected in this study indicated that first Neural Response Imaging (NRI) thresholds had a better correlation with HiResolution most comfortable loudness (M) levels than tNRI thresholds. Electrically evoked auditory reflex thresholds (EARTs) had a higher correlation with HiResolution M levels than tNRI thresholds and a lower correlation than first NRI thresholds. NRI is a very useful method for programming the cochlear implants of young children who cannot demonstrate a reliable judgment of loudness. OBJECTIVE: To investigate how HiResolution sound processing, designed to deliver high-rate stimuli, relates to EARTs and electrically evoked compound action potential measurements produced by low-rate stimuli. MATERIAL AND METHODS: Nine profoundly hearing-impaired children and adults aged 6-29 years participated in the study. NRI responses were elicited using pulse trains consisting of biphasic pulses at a pulse width per phase of 32 micros delivered at a frequency of 30 Hz using SoundWave programming software. Stimuli were delivered to the odd electrodes (1, 3, 5, 7, 9, 11, 13 and 15) along the array. tNRI (NRI threshold) and first NRI thresholds were recorded for each stimulating electrode. "Speech bursts" stimuli used in EARTs recording were delivered to four electrodes at a time and stapedial reflexes were recorded from the impedance bridge. The M levels used were those used by each patient in their everyday HiResolution programs. RESULTS: For 8 patients (53 stimulating electrodes) the correlation between tNRI threshold and M level was r=0.675 (p=0.000) and that between first NRI thresholds and M level was r=0.741 (p=0.000). On average the M-level value was 20 CU (Current Unit) lower than the first NRI threshold value and 12 CU higher than the tNRI threshold value. The M-level patterns across the electrode array overall were similar to the tNRI or first NRI threshold patterns. For 7 patients (112 stimulating electrodes) the correlation between EART and M levels was r=0.710 (p=0.000). On average the EART value was 14 CU higher than the M-level value.

Adolescent↗
PubMed1982

Auditory masking effects on lingual vibrotactile thresholds.

Auditory interaction effects on lingual vibrotactile thresholds were examined for 20 adult subjects. The thresholds from two different masking conditions were compared to the thresholds from a no-masking condition for three different frequencies. Results showed no auditory interference on obtained thresholds for any condition with any frequency. Future research endeavors are discussed with respect to gaining a more complete understanding of auditory interactions in lingual vibrotactile threshold measurement.

Adult↗
PubMed1998

Auditory arousal thresholds are higher when infants sleep in the prone position.

OBJECTIVE: To evaluate the possibility that infants sleeping in the prone position have higher arousal thresholds to auditory challenges than when sleeping in the supine position. STUDY DESIGN: Polygraphic recordings were performed for 1 night in 25 healthy infants with a median age of 9 weeks. The infants were exposed to white noises of increasing intensities while sleeping successively in the prone and supine positions, or vice versa. Arousal thresholds were defined by the auditory stimuli needed to induce polygraphic arousals. RESULTS: Three infants were excluded from the study because they awoke while their position was being changed. For the 22 infants included in the analysis, more intense auditory stimuli were needed to arouse the infants in the prone position than those in the supine body position (p = 0.011). Arousal thresholds were higher in the prone than in the supine position in 15 infants; unchanged in 4 infants; and lower in the prone position in 3 infants (p = 0.007). CONCLUSIONS: Infants show higher arousal thresholds to auditory challenges when sleeping in the prone position than when sleeping in the supine position. The finding could be relevant to mechanisms concerned with the reported association between sudden deaths and the prone sleeping position in infants.

Auditory Threshold↗
PubMed1984

On-line computer scoring of the auditory brainstem response for estimation of hearing threshold.

Auditory brainstem responses (ABRs) to click stimuli have become established as a useful indicator of hearing thresholds in infants and young children. Although the investigation is objective in so far as the patient is concerned, a subjective element remains in the decision by the operator as to whether or not an ABR is present in an averaged waveform. A simple on-line computer detection technique is described which removes some of the reliance placed upon the operator. The technique employs a scanning window for correlation and amplitude analysis of pairs of averaged ABR waveforms. The reliability and accuracy of computer and operator scoring of 25 thresholds in normally hearing adults and 50 thresholds in infants and young children with suspected hearing impairment have been investigated. In the adult group, 96% of computer estimates of the threshold were within +/- 10 dB of the subjective hearing threshold, compared with 92% for operator scoring. There were 92% of computer and operator scores within +/- 10 dB of each other. In the patient group there was equally good agreement between computer and operator scoring with 90% of the thresholds within +/- 10 dB of each other; the incidence of possible false-positive thresholds was also lower with computer scoring. This on-line scoring technique, therefore, offers useful assistance to the operator; requires only limited computing power, and is suitable for use in a routine clinical environment.

Adult↗