Ipsilateral Acoustic Reflex Thresholds Research Articles

Ipsilateral Acoustic Reflex Thresholds at Varying Click Rates in Humans

The effects of the click repetition rates on the ipsilateral acoustic reflex thresholds were investigated in 17 normal female subjects (total 34 ears) within the age-range of 20 to 26 years. The acoustic reflexes were elicited in response to condensation clicks (100 microseconds duration) at repetition rates of 50, 100, 150, 200, 250 and 300/sec. The probe tone frequency was 226 Hz and the intensity was 85dB SPL. The thresholds improved significantly with increase in the repetition rates. The mean threshold advantage was 11.2dB with an increase in the rate from 50 to 100/sec, it was 7.8dB when the rate was increased from 100 to 200/sec and was further reduced to 2.6dB when the rate was increased from 200 to 300/sec. These findings are discussed with reference to the temporal and the spatial summation and facilitation. Possible clinical implications of the findings are presented.

Effect of click‐repetition rate on acoustic reflex growth

Effects of click‐repetition rate on acoustic reflex growth were studied in 11 young female subjects (total 22 ears). The probe tone frequency was 226 Hz and the intensity was 85 dB SPL. Following the determination of ipsilateral acoustic reflex thresholds in response to condensation clicks at repetition rate of 50, 100, 150, 200, 250 and 300/s, reflex amplitudes were measured at levels 5 and 10 dB above the thresholds. For each of the measurements data were obtained across three trials. In 10 of the ears evaluated, data were also obtained at 95 dB peSPL for each of the repetition rate that revealed that acoustic reflex amplitudes increase with increase in repetition rates. A significant effect of repetition rate and sensation level and a significant interaction was apparent for the amplitudes obtained at 5‐ and 10‐dB sensation level (SL). For all the repetition rates 10 dB SL yielded higher amplitudes than those obtained at 5 dB SL except at the 50/s rate where increase in sensation level did not produce any significant increase in amplitudes. Detailed analyses will be presented and the results will be discussed with reference to rate integration in the acoustic reflex pathway. [Work supported by Bloomsburg University Grants for Research and Creative Projects and State System of Higher Education Minority Faculty Development Fund, Pennsylvania.]

Hearing in the Elderly

Many studies have documented the decline in auditory function with age. We broaden that data base in this the first of a series of reports emanating from the auditory testing of the Framingham cohort during biennial exam 18. The results of the auditory questionnaire, hearing sensitivity, acoustic compliance measures, and word recognition tests obtained from 1662 men and women in their 60th through 90th decades are presented. Pure-tone thresholds increased with age but the rate of change with age did not differ by gender even though men had poorer threshold sensitivity. Maximum word recognition ability declined with age more rapidly in men than in women and was poorer in men than in women at all ages. Acoustic compliance and middle ear pressure did not vary with gender or age. Acoustic reflex thresholds to a contralateral stimulus at 1 kHz increased slightly with age, more in women than in men; ipsilateral acoustic reflex thresholds did not vary with age or gender. Hearing aids were being used in only 10% of subjects likely to benefit from amplification.

Objective diagnosis of otitis media in early infancy by tympanometry and ipsilateral acoustic reflex thresholds

Otitis media in early infancy carries a high risk of recurrent otitis media and prolonged middle ear effusion. To fulfill the need for objective diagnostic methods in this age group, we investigated susceptance tympanograms and ipsilateral acoustic reflex thresholds in infants younger than 5 months of age. Tympanometry and acoustic reflex thresholds were performed with an otoadmittance meter using a 660 Hz probe tone. Tympanograms were interpreted using quantitative measures. These findings were compared with independent otoscopic diagnoses in 67 ears with middle ear effusion and 69 ears that were effusion free. Diagnoses were confirmed by tympanocentesis when clinically indicated. There was excellent agreement among otoscopy, peak tympanogram susceptance, and ipsilateral acoustic reflex thresholds (kappa 0.82 to 0.86, agreement 91% to 93%). We conclude that susceptance tympanograms and ipsilateral acoustic reflex thresholds are accurate diagnostic tests for otitis media in infants younger than 5 months of age.

Acoustic reflex abnormalities in behaviorally disturbed and language delayed children.

Contralateral and ipsilateral acoustic reflex thresholds were measured in 62 subjects referred for suspected delays in development of language, learning disabilities, or disorders of auditory processing, with normal peripheral hearing thresholds and normal tympanometry. Thirty-two percent of the subjects in this study showed abnormal contralateral and ipsilateral acoustic reflex thresholds. Both contralateral and ipsilateral acoustic reflex thresholds were involved when subjects showed abnormal reflex thresholds. Although a high percentage of abnormal acoustic reflexes occurred in this population, no strong correlation could be found with specific areas of language delay. A slight positive correlation was found between abnormal acoustic reflexes and delayed psychomotor development. Increased or absent acoustic reflex thresholds are usually associated with peripheral or low brain stem pathologies. While not conclusive, these results suggest brain stem involvement in this population.

Ipsilateral acoustic reflexes in infants.

Ipsilateral acoustic reflex thresholds were studied in otoscopically normal ears of infants 2 weeks to 12 months old. Probe tones of 220 and 660 Hz and pure tone activators were used. Reflex recordings were free of activator artifact and were measured using quantitative standards. Reflexes were detected in 85% to 95% of infant ears for 500, 1,000, and 2,000 Hz activators but were present in only 76% of ears at 4,000 Hz. Median thresholds of 80 to 85 dB hearing level were obtained with all activators and both probe tones. There were no differences in proportions of reflexes obtained with the two probe tones. With a 500-Hz activator, thresholds at 220 Hz were lower than those at 660 Hz, while no threshold differences were demonstrated between probe tones at other activators. No relationship was demonstrated between age in the first year of life and presence or threshold of reflexes. Ipsilateral acoustic reflex measures have potential use in the identification of hearing loss and middle ear disease in infancy.

Ipsilateral Acoustic Reflex Thresholds in Neonates and in Normal-Hearing and Hearing-Impaired Pre-School Children

Ipsilateral Acoustic Reflex Thresholds in Neonates and in Normal-Hearing and Hearing-Impaired Pre-School Children

Ipsilateral acoustic reflex thresholds in neonates and in normal-hearing and hearing-impaired pre-school children.

Acoustic reflex thresholds (ART) were measured ipsilaterally in 20 neonates, 220 children with normal hearing and 56 children with sensorineural hearing loss, using a probe-tone frequency of 660 Hz. Middle-ear function was assessed with tympanometry (220 Hz probe tone) in all children. All the neonates had normal tympanograms and middle- ear pressure better than -- 1kPa, even a few hours after birth. The mean acoustic reflex threshold (ART) averaged over the frequency range 0.5-4 kHz was 85 dB HL, with standard deviations (SD) varying between 5 and 9 dB. With broad-band noise (BBN), the mean ART average was 57 dB HL with SD +/- 10 dB. Measurements of the ART on the children with normal-hearing and at an age of 1 month up to 5 years showed that the ARTs increased in relation to age. At 4 kHz the ARTs increased from an age of 2 months. At an age of one year 28% of 40 ears failed to manifest a reflex at the maximum testing level (90 dB HL). At frequencies 1.0 and 2.0 kHz the mean ART increased from 85 dB HL in neonates to 90 and 92 dB HL at an age of 5 years. The standard deviations in the different age groups varied between 4 and 9 dB for pure tones and 6-8 dB for BBN. Twenty (9%) of the 220 children with normal hearing had elevated ARTs by puretone stimuli and 19 by BBN. No reflexes could be elicited at 0.5 kHz and at 1.0 and 2.0 kHz the ARTs were abnormally elevated.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of hearing loss with ipsilateral acoustic reflex thresholds.

This study consisted of two experiments both of which involved measurement of the ipsilateral acoustic reflex threshold (ART). In Experiment I, ipsilateral ARTs were measured in normal-hearing adults for a 2 000-Hz tone and computer-generated complex stimuli of varying bandwidth. Results of this experiment revealed that the bandwidth effect for the ipsilateral ART was similar to the contralateral effect. The ART decreased monotonically as a function of bandwidth of the reflex-eliciting stimulus. Results of Experiment II indicated that ipsilateral ARTs successfully differentiated between normal hearing and significant hearing loss, in difficult-to-test groups of young children, when used with the bivariate plotting procedure. In addition, obtaining reflexes ipsilaterally, rather than contralaterally, appeared to have advantages with this population. The ipsilateral test apparatus is less cumbersome, the possibility of calibration error from a malpositioned contralateral earphone is eliminated and the children were generally more accepting of the ipsilateral assembly.

Normal values of the ipsilateral acoustic stapedius reflex threshold.

It is frequently taken for granted that the acoustically evoked stapedius reflex is bilaterally symmetrical. Contrary to this, Møller described an asymmetry of the acoustic stapedius reflex with an ipsilaterally 2--14 dB lower threshold. The determination of normal values of the ipsilateral acoustic stapedius reflex threshold with a large number of patients is difficult as the intensity of the stimulus depends considerably on the position of the probe in the acoustic meatus and is therefore not defined with sufficient accuracy. For this reason we determined the values of the ipsilateral threshold by applying a stimulus sound of high intensity to the deaf ear of unilaterally completely deaf patients with a normal headphone, which can be calibrated much more accurately. After subtraction of the individual cross hearing loss, the exact ipsilateral intensity was obtained. By this method a stapedius reflex could be evoked with 49 of the 62 patients. By mathematical consideration of the data of the positive cases, as well as the maximum available intensities with the negative cases, determination of the median value of the ipsilateral threshold was possible: at 0.5 kHz 59 dB; at 1kHz 62.5 dB; at 2 kHz 67 dB; at 4 kHz approx. 67 dB. The difference between ipsilateral and contralateral stapedius reflex threshold was in the range of 15 dB. A new definition of the normal value for the ipsilateral measured Metz recruitment appears necessary.