Evaluation of prescriptive fitting.

The purpose of this study was to determine the minimum tolerance needed when choosing a manufacturer who custom-built analog circuitry for all-in-the-ear hearing aids to match a popular prescriptive amplification formula. Given the tolerance, a second purpose was to evaluate fitting success by calculating the differences in prescribed versus preferred gain and pre- versus postfitting perceived benefits. Eight elderly adults with mild to moderate sensorineural hearing losses participated. Real ear measurements were obtained via a probe-tube microphone system. Even when providing for the optimal scenario of custom-building the circuitry, the inherent limitations of analog technology allowed no better than a +/- 12 dB electroacoustic match to prescribed gain. Although the minimum tolerance found was less than previous studies, it was still considered excessive given the differences in prescribed gain among formulae. Regardless of the large tolerance and a preference for less gain than prescribed, the subjects reported substantial benefit with the fitting approach.

Interaction of stimulus parameters on the auditory brain stem response: a normal variant.

The purpose of this investigation was to further define the effect that stimulus parameters of phase, intensity, and rate have in significantly reducing the wave V amplitude. Two separate experiments were conducted to determine whether an interactive effect exists and how robust the effect was on wave V. Results revealed that wave V amplitude was reduced to less than half the absolute amplitude of the wave IV-V complex in 9 of the 39 subjects. The phenomenon was dependent upon stimulus parameters of rarefaction phase, high intensity, and low repetition rate. Conversely, the phenomenon was independent of cochlear integrity, sex, and test equipment. The implications to diagnostic interpretation during routine auditory brain stem response testing are discussed.

Cordless telephones and acoustic trauma: a case study.

Cordless telephones have been reported to cause irreversible damage to the ear due to acoustic trauma. The present case study reports an unusual audiometric configuration associated with direct exposure to the ring from a cordless phone. Although pure-tone sensitivity was only moderately affected, speech understanding was severely compromised.

Auditory brainstem response with high stimulus rates in normal and patient populations.

Normative data were collected on 48 subjects to determine the effects of increasing stimulus rates on the auditory brainstem response. These subjects were then compared to 221 patients referred for otoneurologic evaluation. The 90 patients with impaired auditory sensitivity demonstrated significantly less wave V latency shift than either the 131 patients with normal auditory sensitivity or the normal subjects. The incidence of abnormal wave V latency shift was 12% in the patients with normal auditory sensitivity and 8% in the patients with impaired auditory sensitivity. The high stimulus rate was often the only ABR parameter indicative of brainstem involvement in patients with documented CNS pathology. The authors conclude that a high stimulus rate contributes to the diagnosis of brainstem pathology often enough to warrant its routine use.

Brainstem conduction abnormalities in spasmodic dysphonia.

Twelve spasmodic dysphonia patients were evaluated by three different auditory brainstem response parameters; 75% were abnormal. Three of the 12 had prolonged wave I-V interpeak latency. Seven had pathologic wave V latency shifts at a high stimulus rate. Amplitude ratios were normal for all subjects. The authors hypothesize that spasmodic dysphonia is a disorder of variable cranial nerve symptom presentations, and offer several possible models to account for its sporadic representation in the nervous system.

Auditory brainstem response abnormalities in adductor spasmodic dysphonia.

Six patients with adductor spasmodic dysphonia were evaluated for evidence of brainstem dysfunction using the auditory brainstem response (ABR). In four, abnormally large increments in wave V latencies were found at high stimulus repetition rates. Latency increments exceeded three standard deviations above the mean in a normative adult population. A fifth patient had the prolonged interpeak latencies described previously by other investigators. In five of six patients the capacity of the auditory brainstem to conduct impulses was compromised. These results suggest a central nervous system abnormality in adductor spasmodic dysphonia.

A modified polymer foam earplug for the hearing aid evaluation.

Functional gain was compared with 12 subjects using three earmold conditions: an E-A-R polymer foam earplug modified for use with a hearing aid, a personal custom earmold, and a best-fit receiver-type stock earmold. Functional gain was equivalent between the modified E-A-R earplug and the custom earmold conditions. The stock earmold condition resulted in a significant shunting of low-frequency amplification. The gain control of the personal hearing aids could be adjusted to the user comfort level gain setting without resulting in acoustic feedback in only the modified E-A-R earplug and custom earmold conditions. These findings are discussed relative to the hearing aid evaluation.

A sound effects recognition test for the pediatric audiological evaluation.

In this paper, we describe the development and evaluation of a Sound Effects Recognition Test as part of the pediatric audiological evaluation. Such a test may be the only available standardized measure of auditory discrimination in certain children with very limited verbal abilities. The test is comprised of 3 equivalent sets, each containing 10 familiar environmental sounds. Results for normal-hearing pre-schoolers are presented with suggestions for clinical application of the test with hearing-impaired patients.