Biomedical subjects

R H Frey

Publications and source records attributed to R H Frey.

At least 19 recordsLinked to original sources

PubMed1999

An individualized, sensitive frequency range for early detection of ototoxicity.

OBJECTIVE: The aim of this study was to identify auditory frequencies at which serial threshold testing would provide the greatest sensitivity for early detection of ototoxicity. The overall objective is to develop a more time-efficient ototoxicity monitoring protocol. DESIGN: Threshold data were analyzed from 370 hospitalized patients treated with aminoglycoside antibiotics (AMGs) or cisplatin (CDDP) who received serial auditory monitoring before, during, and after treatment at conventional (0.25 to 8 kHz) and high (9 to 20 kHz) frequencies. RESULTS: For patients showing hearing changes due to ototoxicity, a frequency range was identified for its apparent high sensitivity to initial ototoxicity. This sensitive range is identified according to an individual's hearing threshold configuration, and is, therefore, unique for each patient. The range consists of five frequencies, generally separated by 1/6 octave, e.g., 8, 9, 10, 11.2, and 12.5 kHz. To determine frequencies and combinations of frequencies that were most often involved in ototoxicity detection, threshold data in the sensitive range were analyzed in detail. This analysis suggests that patients receiving treatment with AMG or CDDP can be monitored for hearing thresholds at only five frequencies, resulting in an 84% detection rate for AMG and 94% for CDDP compared with monitoring at all conventional and high frequencies. CONCLUSIONS: This comprehensive analysis supports earlier observations that a sensitive, limited frequency range exists in which serial threshold monitoring will provide early warning of ototoxicity before effects in the speech frequency range. This finding is now being evaluated in a prospective investigation.

Aminoglycosides↗

PubMed1998

Intrasubject reliability of high-frequency (9-14 kHz) thresholds: tested separately vs. following conventional-frequency testing.

Retrospective analysis of hearing-threshold data from a multisite ototoxicity monitoring study identified an individualized range of predominantly high frequencies (> 8 kHz) that appeared to be highly sensitive to early threshold changes caused by ototoxicity. This suggested the potential for a limited-frequency monitoring protocol that could be conducted rapidly without compromising sensitivity to ototoxicity. Such testing would require high-frequency thresholds to be obtained independently, that is, without prior testing at conventional frequencies (0.25-8 kHz). This study was conducted to determine the test-retest reliability of isolated threshold testing in a "target" frequency range of high frequencies (9, 10, 11.2, 12.5, and 14 kHz) that represented a shortened ototoxicity monitoring test. Twenty normal-hearing subjects were evaluated over five sessions. During each session, subjects were tested in each of two conditions: (1) conventional frequencies (0.25-8 kHz) tested first, followed by target frequencies; and (2) target frequencies tested alone (isolation condition). Depending on test frequency, reliability of high-frequency thresholds was either unchanged or improved in the isolation condition. Although these results cannot be generalized to ill hospitalized patients, who may also have pre-existing hearing loss, they lay the groundwork for development of a time-saving limited-frequency test to monitor for ototoxicity in these patients.

Adult↗

PubMed1995

High-frequency toneburst-evoked ABR latency-intensity functions in sensorineural hearing-impaired humans.

The latency-intensity functions (LIFs) of ABRs elicited by high-frequency (8, 10, 12, and 14 kHz) toneburst stimuli were evaluated in 20 subjects with confirmed 'moderate' high-frequency sensorineural hearing loss. Wave V results from clicks and tonebursts revealed all intra- and intersession data to be reliable (p > 0.05). Linear regression curves were highly significant (p < or = 0.0001), indicating linear relationships for all stimuli analyzed. Comparisons between the linear regression curves from a previously reported normal-hearing subject group and this sensorineural hearing-impaired group showed no significant differences. This study demonstrated that tonebursts at 8, 10, and 12 kHz evoked ABRs which decreased in latency as a function of increasing intensity and that these LIFs were consistent and orderly (14 kHz was not determinable). These results will contribute information to facilitate the establishment of change criteria used to predict change in hearing during treatment with ototoxic medications.

Acoustic Stimulation↗

PubMed1994

Paired tone-burst study of auditory brainstem response adaptation in guinea pigs: implications for development of multiple-stimulus methods.

In clinical testing using auditory evoked potentials, the practical length of a test session is limited. Thus, the amount of information that can be obtained during a routine test session is limited in electrocochleography and auditory brainstem testing. Attempts to obtain more information within a test session by increasing the stimulus repetition rate yields adapted responses. Multiple-stimulus method that present sequences of stimuli at different frequencies and intensities can increase the efficiency of data collection while avoiding adaptation. This study was designed to investigate rapid adaptation of these early responses to enable more efficient data acquisition using multiple stimuli. Five experiments in guinea pigs using single and paired tone-burst stimuli are described. The intrapair time, frequency, and intensity were varied to determine when adaptation, measured by a latency delay, occurred. The effects of adaptation on waves I through IV are described. The differences in stimulus parameters that avoid adaptation can be determined from these experiments.

Acoustic Stimulation↗

PubMed1994

Multiple-stimulus method for rapid collection of auditory brainstem responses using high-frequency (> or = 8 kHz) tone bursts.

Auditory brainstem responses (ABR) to high-frequency (> or = 8 kHz) tone-burst stimuli have shown potential for objective early detection of ototoxicity. In the case of ill, unresponsive, or otherwise difficult-to-test individuals, the patient group for whom this test is targeted, a threshold-seeking process can be too lengthy. A new method is described for obtaining responses to several high-frequency tone bursts in the same amount of time as that used in obtaining a single responses. Using 10 normal-hearing subjects, four high-frequency tone-burst stimuli (14, 12, 10, and 8 kHz) were presented singly, then in a multiple-stimulus sequence with onsets separated by 10 msec. Wave V response latencies from the multiple-stimulus sequences are compared to those presented singly, with small but statistically significant longer latencies observed for all stimuli following the initial stimulus (14 kHz) in the multiple sequence. Test-retest reliability was comparable between multiple and single conditions. These findings support the development of this technique for clinical auditory monitoring.

Acoustic Stimulation↗

PubMed1993

High-frequency monitoring for early detection of cisplatin ototoxicity.

Cisplatin can cause irreversible hearing loss initially detectable as impairment of high-frequency hearing with progression to lower frequencies. Many patients receiving cisplatin are too ill to tolerate lengthy audiometric testing. Therefore, a rapid and sensitive high-frequency monitoring strategy to detect cisplatin-induced ototoxicity is needed. Serial conventional (0.25 to 8 kHz) and high-frequency (> or = 8 kHz) threshold monitoring was performed in patients receiving cisplatin, resulting in 84% of ears showing hearing loss, of which 71% were detected first in frequencies of 8 kHz or greater. By analysis according to an individualized, specific high-frequency range, early identification of hearing loss occurred in 94% of ears showing change. This five-frequency procedure is a sensitive detector of ototoxicity and is proposed as an alternative monitoring protocol for patients receiving cisplatin who cannot tolerate extended testing.

Algorithms↗

PubMed1993

High-frequency tone burst-evoked ABR latency-intensity functions.

High-frequency tone burst stimuli (8, 10, 12, and 14 kHz) have been developed and demonstrated to provide reliable and valid auditory brainstem responses (ABRs) in normal-hearing subjects. In this study, latency-intensity functions (LIFs) were determined using these stimuli in 14 normal-hearing individuals. Significant shifts in response latency occurred as a function of stimulus intensity for all tone burst frequencies. For each 10 dB shift in intensity, latency shifts for waves I and V were statistically significant except for one isolated instance. LIF slopes were comparable between frequencies, ranging from 0.020 to 0.030 msec/dB. These normal LIFs for high-frequency tone burst-evoked ABRs suggest the degree of response latency change that might be expected from, for example, progressive hearing loss due to ototoxic insult, although these phenomena may not be directly related.

Acoustic Stimulation↗

PubMed1993

High-frequency testing techniques and instrumentation for early detection of ototoxicity.

Veteran patients with certain types of infections and cancers are routinely treated with therapeutic agents having ototoxic potential, thus threatening loss of hearing sensitivity which preexists in the majority of these patients. To prevent communication deficits requiring intervention, this laboratory is developing instrumentation and techniques for early detection of ototoxicity. For this study, conventional (< or = 8 kHz) and high-frequency (> or = 8 kHz) hearing thresholds were monitored behaviorally in hospitalized veterans receiving treatment with ototoxic drugs. Data analysis revealed that monitoring only the high-frequency range would have identified 67% of ears showing change. A five-frequency range of hearing, specific to each individual, was identified for its high sensitivity to early ototoxic change. Monitoring of only these five frequencies in each patient would have identified 82% of ears that showed behavioral change. Auditory brainstem responses (ABR) were obtained in a subgroup using clicks and high-frequency (8-14 kHz) tone bursts. ABR latency/morphology changes were observed in 95% of ears demonstrating behavioral change. High-frequency tone-burst-evoked ABRs alone would have identified 93% of initial changes. Monitoring of high-frequency audition using these techniques shows promise for early detection of ototoxicity with potential for prevention of hearing loss in frequencies essential for verbal communication.

Acoustic Impedance Tests↗

PubMed1992

High-frequency audiometric monitoring for early detection of aminoglycoside ototoxicity.

Treatment with aminoglycosides is known to cause irreversible hearing loss, typically affecting higher-frequency hearing first and progressing to lower frequencies. Standardized methodology has not been developed for early detection of ototoxicity. Serial conventional (0.25-8 kHz) and high-frequency (9-20 kHz) hearing threshold monitoring was done prospectively in 53 hospitalized patients administered aminoglycosides. Hearing loss occurred in 47% of the ears studied, with hearing loss first appearing in the high-frequency range in 71% of ears showing change. Analysis of data on an individual basis revealed a five-frequency range most susceptible to initial ototoxicity. Testing only this range would have resulted in early identification of 82% of ears showing change. Results confirm the critical need for serial auditory threshold monitoring encompassing high frequencies in patients receiving aminoglycosides. A shortened five-frequency monitoring protocol is presented and suggested for use with patients unable to tolerate lengthy audiometric testing procedures.

Amikacin↗

PubMed1992

Comparing laboratory and portable tone-burst auditory brain-stem-response (ABR) systems for monitoring high-frequency (> or = 8 kHz) auditory function.

High-frequency (8-20 kHz) hearing sensitivity is of special interest because of its early warning potential for ototoxicity. Many ill patients, however, are unable to respond behaviorally to auditory test procedures. To objectively monitor high-frequency auditory function in these patients, laboratory instrumentation to evoke the auditory brain-stem response (ABR) with high-frequency (8-14 kHz) tone-burst stimuli was developed and documented. To provide evaluation at bedside, a portable high-frequency tone-burst generator was developed to elicit the ABR. Combined with a portable signal averager, this system was validated by comparison with the laboratory system. Thirty-five normal-hearing subjects were used to compare ABRs to high-frequency tone bursts from each system. Analysis of responses to tone bursts revealed no significant mean latency differences, and no significant intersession reliability differences between systems. These results confirm that the portable system is comparable to the laboratory system in obtaining reliable high-frequency tone-burst responses.

Acoustic Stimulation↗

PubMed1992

Early detection of ototoxicity using high-frequency, tone-burst-evoked auditory brainstem responses.

Subjects receiving treatment with ototoxic agents were evaluated concurrently with conventional and high-frequency (> or = 8 kHz) behavioral threshold measures and with ABR to click and to 8, 10, 12, and 14 kHz tone-burst stimuli. Behavioral threshold data revealed ototoxic change in 51 percent of ears evaluated. Of these ears demonstrating behavioral change, 90 percent revealed concurrent ABR changes. If only ABR monitoring with high-frequency tone-burst stimuli had been used, 87 percent of allears showing behavioral change would have been identified. Three fourths of these would have been identified from wave V responses, with 87 percent identified from the two highest frequencies tested for each individual. This research suggests that behavioral change is reflected accurately in the ABR, that high-frequency tone bursts will identify a majority of initial ototoxic changes, and that monitoring hearing with high-frequency, tone-burst-evoked ABRs during treatment with potentially ototoxic agents is significantly more effective than click-evoked ABRs for early detection of ototoxicity.

Acoustic Impedance Tests↗

PubMed1992

Portable stimulus generator for obtaining high-frequency (8-14 kHz) auditory brainstem responses.

Currently, the most useful application of high-frequency (greater than or equal to 8 kHz) auditory evaluation is for serial monitoring of patients receiving potentially ototoxic agents. Many individuals, however, are unable to respond to behavioral auditory test techniques. An objective evaluation method such as the auditory brainstem response (ABR) is valuable with difficult-to-test individuals. Laboratory instrumentation has been demonstrated to evoke high-frequency-specific (8-14 kHz) ABRs with reliable intrasubject latencies over time. This instrumentation is limited, however, because it cannot be transported to the patient confined to a hospital room. A portable device has now been constructed to deliver high-frequency (8-14 kHz) tone-burst stimuli comparable to the lab system. This digital/analog high-frequency tone-burst stimulus generator weighs less than 5 pounds. It can be utilized with any ABR signal averager capable of generating a positive (condensing) click at approximately 4.8 volts. Case studies are presented to demonstrate the frequency-specific responses obtained with these high-frequency tone-burst stimuli.

Acoustic Stimulation↗

PubMed1991

Rise time and center-frequency effects on auditory brainstem responses to high-frequency tone bursts.

The effects of rise time and center frequency on the auditory brainstem response (ABR) elicited by high-frequency tone bursts were examined in six normal-hearing adults. Tone bursts with rise times of 0.1, 0.25, 0.5, and 1.0 msec, duration of 2 msec, and center frequencies of 8, 10, and 12 kHz were used in this study. The absolute latencies of waves I, III, and V were obtained in all subjects, and interpeak intervals of I-III, III-V, and I-V were calculated. As would be expected, rise time significantly affected the absolute latencies of waves I, III, and V, i.e., faster rise times shortened the absolute latencies, but did not affect the interpeak latencies. The tone-burst frequency significantly affected the latency of wave I but not the later waves. No significant differences were found in reliability of the response at different rise times or frequencies, within or across sessions. An estimate of the effective bandwidth of the stimulus suggests that frequency specificity of the response is maintained with fast rise time tone-burst stimuli.

Acoustic Stimulation↗

PubMed1991

Reliability of evoked responses to high-frequency (8-14 kHz) tone bursts.

Instrumentation to evaluate the auditory brainstem response to high-frequency (8-14 kHz) tone bursts has been developed in the Auditory Research Laboratory, Portland, Oregon VA Medical Center. This system is intended to monitor the audition of patients receiving ototoxic drugs who are unresponsive to behavioral test procedures. The reliability of responses obtained with the high-frequency tone-burst system was studied in 30 normal ears. Intrasubject variability of intersession data from response waves I, III, and V to tone bursts of frequencies 8, 10, 12, and 14 kHz was not significantly different from click response variability. The results of this study demonstrate the reliability of the ABR to these high-frequency tone-burst stimuli. This technique may provide early identification of hearing loss in unresponsive subjects receiving treatment with potentially ototoxic agents, thus allowing alternative treatments to minimize or prevent communicative handicap.

Acoustic Stimulation↗

PubMed1991

Masked high-frequency bone-conduction audiometry: test reliability.

The present study examines the reliability of masked high-frequency bone-conduction threshold measurements in 95 normal-hearing subjects. High-frequency pure-tone air-and bone-conduction thresholds were measured with a dedicated laboratory high-frequency auditory evaluation system using matched, modified Koss Pro/4X Plus earphones, and the Pracitronic KH 70/5 bone vibrator. A 400-Hz wide band masking noise centered at the frequency of the test tone was used to mask the nontest ear. Monaural masked bone-conduction threshold measurements were obtained at the ipsilateral mastoid of the ear with better high-frequency hearing. Two measurements were performed in each session, and each subject participated in two sessions. In several comparisons for test-retest consistency, high-frequency bone-conduction threshold measurements were as repeatable as air-conduction thresholds of identical frequency, or bone-conduction thresholds for frequencies of 4 kHz and less. High-frequency bone-conduction threshold measurement appears to be a sufficiently reliable tool for diagnosis of auditory disorders.

Adolescent↗

PubMed1990

Effects of contralateral masking on high-frequency bone-conduction thresholds.

The present study reports effects of contralateral masking on high-frequency threshold force levels in 28 normal-hearing subjects. High-frequency air- and bone-conduction thresholds were measured with a high-frequency auditory evaluation system using matched Koss HV/1A earphones and the Pracitronic KH 70/5 bone vibrator. Measurements were made for both unmasked and masked bone-conduction thresholds at the ipsilateral mastoid of the better ear. The contralateral masked condition was performed using 30-dB-SL 400-Hz narrow-band masking noise centered at frequency of test tone. The results demonstrated that masked high-frequency bone-conduction thresholds were 1.5 to 3.4 dB poorer than the unmasked thresholds and that these differences were statistically significant at 0.01 level of confidence except at 12 kHz. ANSI and ISO standards for bone-conduction threshold force levels for frequencies below 8.0 kHz have been established with contralateral masking stimuli. This study supports the need to use effective contralateral masking to eliminate cross hearing in investigations of high-frequency bone-conduction threshold measurements.

Adult↗

PubMed1990

Reliability and validity of high-frequency (8-20 kHz) thresholds obtained on a computer-based audiometer as compared to a documented laboratory system.

A Macintosh computer-based audiometer (Virtual 320) was evaluated for reliability and validity of high-frequency (8-20 kHz) thresholds by comparison with a well documented laboratory high-frequency evaluation system (PARVA-HF). High-frequency earphones originally provided with the V320 for high-frequency testing required modification to improve reliability in calibration and in subject threshold testing. Twenty normal-hearing adults were evaluated in the 8-20 kHz frequency range on both testing systems. Results of intrasubject multiple-session testing were evaluated to determine the reliability of high-frequency thresholds obtained. The V320 produced reliable results comparable to the PARVA-HF. Validity of high-frequency thresholds was inferred by comparing V320 responses to those obtained with the PARVA-HF. Comparable findings between systems imply validity of thresholds obtained with the V320. Conventional frequency (0.25-8 kHz) threshold evaluation with the V320 and a Grason-Stadler 1701 audiometer also yielded comparable results.

Adult↗

PubMed1986

Age categorization of high-frequency auditory threshold data.

This article presents high-frequency (8- to 20-kHz) auditory threshold measurements for 157 subjects with normal conventional hearing, ranging in age from 6-30 years. Normative descriptive data are provided in five semidecade age categories. Intra-age category mean and variance values for threshold sensitivity and interaural threshold differences are included. Generally, the data are consistent with the expectation of a gradual diminution of high-frequency sensitivity through the adolescent and early adult years. Several unresolved issues related to high-frequency normative data and clinical applicability of high-frequency threshold measurements are discussed.

Adolescent↗