Clinical trial to compare tinnitus masking and tinnitus retraining therapy.

CONCLUSION: Both tinnitus masking (TM) and tinnitus retraining therapy (TRT) can be effective therapies for amelioration of tinnitus. TM may be more effective for patients in the short term, but with continued treatment TRT may produce the greatest effects. OBJECTIVES: Although TM and TRT have been used for many years, research has not documented definitively the efficacy of these methods. The present study was a controlled clinical trial to prospectively evaluate the clinical efficacy of these two methods for US military veterans with severe tinnitus. SUBJECTS AND METHODS: Over 800 veterans were screened to ensure that enrolled patients had tinnitus of sufficient severity to justify 18 months of individualized treatment. Qualifying patients (n=123) were placed quasi-randomly (alternating placement) into treatment with either TM or TRT. Treatment was administered at 0, 3, 6, 12, and 18 months. Outcomes of treatment were evaluated primarily using three self-administered tinnitus questionnaires (Tinnitus Handicap Inventory, Tinnitus Handicap Questionnaire, Tinnitus Severity Index). RESULTS: Findings are presented from the three written questionnaires with respect to three categories of patients: describing tinnitus as a 'moderate,' 'big,' and 'very big' problem at baseline. Based on effect sizes, both groups showed considerable improvement overall. In general, TM effects remained fairly constant over time while TRT effects improved incrementally. For the patients with a 'moderate' and 'big' problem, TM provided the greatest benefit at 3 and 6 months; benefit to these TRT patients was slightly greater at 12 months, and much greater at 18 months. For patients with a 'very big' problem, TM provided the greatest benefit at 3 months. For these latter patients, results were about the same between groups at 6 months, and improvement for TRT was much greater at 12 months, with further gains at 18 months.

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.

A prospective study of high-frequency auditory function in patients receiving oral neomycin.

Orally administered, neomycin is reported to cause ototoxicity rarely. Most reports on hearing loss due to oral neomycin have been case studies. One prospective study of a pediatric sample demonstrated a significant loss of hearing in the frequency range of 2 to 8 kHz in 9 of 17 children. To our knowledge there are no published prospective studies on this type with adult samples and therefore little is known of the true incidence or nature of ototoxicity from oral neomycin. This prospective study presents the results of long-term use of oral neomycin in 30 adult subjects. Hearing sensitivity was serially monitored in the frequency range 250-20,000 Hz. Two of the 30 subjects subsequently revealed ototoxicity. Thus the results of this investigation suggest that clinical use of oral neomycin implies relatively little risk of ototoxicity.

Detection of aminoglycoside ototoxicity by high-frequency auditory evaluation: selected case studies.

A practical monitoring procedure utilizing frequencies higher than those tested by conventional audiometry for the detection of ototoxicity has the potential for preventing or minimizing irreversible communication deficits in patients receiving aminoglycoside antibiotic therapy. If ototoxicity produced by these drugs could be detected before it progresses to involve the frequencies essential for communication, it might be possible to lower the dose or to change to another antibiotic to prevent a permanently handicapping hearing impairment. From a total of 77 patients monitored by serial audiograms, three case studies illustrate the various types of auditory sensitivity changes observed with high-frequency audiometry. Ototoxicity was generally detected by high-frequency auditory testing before it could be detected by conventional audiometric procedures. These cases demonstrate the utility of monitoring audition at frequencies higher than those tested conventionally in patients receiving aminoglycoside antibiotics.

Early detection of cisplatin ototoxicity. Selected case reports.

A recently developed high frequency auditory measurement technique was applied to a sample of patients receiving the antineoplastic agent cis-dichlorodiammineplatinum II (cisplatin [CDDP, DDP]). Ototoxicity as a result of cisplatin administration is well documented. The ability to detect ototoxicity, however, varies with the methods and instrumentation utilized, and the criteria by which ototoxicity is defined. The auditory function of subjects receiving cisplatin for genitourinary tumors and head and neck cancers was serially monitored with conventional audiometry and with a high frequency testing system. Results reveal a high incidence of nonreversible cochlear toxicity with a predilection for involvement of the higher frequencies. Cochlear toxicity was detected earlier with the high frequency evaluation system than with conventional audiometry. The case reports presented are characteristic of the type and magnitude of auditory changes observed.

An investigation of the validity of high-frequency audition.

In this investigation, a masking experiment was utilized to explore the validity of high-frequency audition. Threshold shifts produced by a narrow-band noise with sharp filter slopes and variable center frequency were determined for pure-tone stimuli from 8000 to 14 000 Hz. Subjects were young adults with normal hearing from 250 through 8000 Hz, and with high-frequency thresholds comparable to those obtained in a previously conducted normative survey. After pure-tone thresholds were obtained for each test frequency, a narrow-band masker was presented ipsilateral to the pure-tone stimulus with center frequency equal to the pure tone. The masker was adjusted to an intensity level necessary to shift the pure-tone threshold approximately 17 dB. The center frequency of the masker was then decreased in discrete steps with the pure-tone threshold re-established at each step. The experimental results, as demonstrated by release-from-masking functions, are consistent with the expectation of increased masker effectiveness as the center frequency of the masker approximates the test frequency. The findings of this investigation suggest that responses to high-frequency auditory stimulation are the result of high-frequency perception, and not the perception of some lower frequency distortion process.

The effects of noise upon human hearing sensitivity from 8000 to 20 000 Hz.

High-frequency (8 to 20 kHz) hearing sensitivity was compared in thirty-six, 20 to 29-year-old military veterans with histories of steady-state or impulsive noise exposure. Threshold shifts were prominent for the steady-state noise subjects from 13 to 20 kHz. Mean thresholds from 8 through 12 kHz were maximally 20 dB poorer than a sample of young adult normals. Audiometric configurations for this group were generally smooth and symmetrical above 8000 Hz. For the impulsive noise group, substantial shifts in sensitivity were seen from 2 to 20 kHz and the high-frequency audiometric configurations were often jagged and/or asymmetrical. The variability of subjects in this group was greater than that seen in the steady-state noise exposed sample. Several case studies are presented to illustrate these characteristics. Measurement of auditory sensitivity from 8 to 20 kHz extends the mapping of basal cochlear function, providing information which often is not predictable from conventional audiometric measurement. This additional information provides for more comprehensive inter- and intra-subject comparison of the degree and extent of threshold changes present.