Efficacy of 3 commonly used hearing aid circuits: A crossover trial. NIDCD/VA Hearing Aid Clinical Trial Group.

CONTEXT: Numerous studies have demonstrated that hearing aids provide significant benefit for a wide range of sensorineural hearing loss, but no carefully controlled, multicenter clinical trials comparing hearing aid efficacy have been conducted. OBJECTIVE: To compare the benefits provided to patients with sensorineural hearing loss by 3 commonly used hearing aid circuits. DESIGN: Double-blind, 3-period, 3-treatment crossover trial conducted from May 1996 to February 1998. SETTING: Eight audiology laboratories at Department of Veterans Affairs medical centers across the United States. PATIENTS: A sample of 360 patients with bilateral sensorineural hearing loss (mean age, 67.2 years; 57% male; 78.6% white). INTERVENTION: Patients were randomly assigned to 1 of 6 sequences of linear peak clipper (PC), compression limiter (CL), and wide dynamic range compressor (WDRC) hearing aid circuits. All patients wore each of the 3 hearing aids, which were installed in identical casements, for 3 months. MAIN OUTCOME MEASURES: Results of tests of speech recognition, sound quality, and subjective hearing aid benefit, administered at baseline and after each 3-month intervention with and without a hearing aid. At the end of the experiment, patients ranked the 3 hearing aid circuits. RESULTS: Each circuit markedly improved speech recognition, with greater improvement observed for soft and conversationally loud speech (all 52-dB and 62-dB conditions, P

Dynamic sensorineural hearing loss: implications for audiologists: case reports.

Although many persons with sensorineural hearing loss (SNHL) seeking hearing care do not have active ear disease, audiologists must appreciate the potentially dynamic and treatable nature of some etiologies of SNHL. This is particularly important now as audiologists are increasingly employed in private practice or other clinical settings that may serve as the point of entry for hearing care. In this paper, we review a variety of clinical entities affecting newborn infants, children, and adults that are associated with dynamic SNHL. Using a case report format, we illustrate treatment-related changes in SNHL, emphasizing the audiologist's role in patient management.

Achieving prescribed gain/frequency responses with advances in hearing aid technology.

Technological limitations have restricted the capability of older generation in-the-ear (ITE) hearing aids to closely match prescribed real ear gain/frequency responses. Newer technology, widely available in currently marketed ITE hearing aids, has considerably improved this capability. Data for 60 ears are presented comparing the real ear insertion gain (REIG) actually achieved to the target REIG, using ITE hearing aids having: 1) older generation narrow-band receivers, and amplifiers with single-pole-filter low frequency tone control and a class A amplifier output stage (n = 30), and 2) newer generation amplifiers with a two- or four-pole-filter low frequency tone control, and wide band receivers, containing a class D amplifier output stage (n = 30). With the newer technology ITE hearing aids, the means and ranges of deviation from target gain were reduced. Capability for achieving prescription REIG with ITE hearing aids can be further improved with multichannel amplifiers. Examples of the latter are shown for several difficult-to-fit audiograms.

Ability to achieve gain/frequency response and SSPL-90 under three prescription formulas with in-the-ear hearing aids.

Custom in-the-ear (ITE) hearing aids (standard linear amplifiers with single-pole-filter low-frequency tone control and a class A amplifier output stage) were fit to 90 ears using the revised National Acoustics Laboratories' formula (NAL-R), and to 20 ears each using Prescription of Gain/Output II (POGO II) and Memphis State University (MSU) formulas. Both real-ear insertion gain and 2-cc coupler gain were evaluated. Examination of differences between prescribed gain and that actually achieved in the fittings revealed that too much gain was often given in the low- and mid-frequency range and insufficient gain in the high frequencies. There was little difference among the formulas in the degree of deviation from target. For some fittings, the deviation resulted in poorer predicted speech recognition scores (modified Speech Transmission Index). For the POGO II and MSU methods, underfitting of prescribed SSPL-90 values was far more common than overfitting.

Validity of hearing thresholds obtained from the rising portion of the audiogram in sensorineural hearing loss.

Two experiments were performed for this study. The purpose of both experiments was to examine the validity of pure-tone hearing thresholds obtained near the rising portion of a sensorineural hearing loss. Recent work by other investigators has suggested that thresholds obtained near the rising portion of the audiogram may not correspond to the severity of damage at the cochlear place associated with the test frequency. In the first experiment this issue was addressed in 11 subjects having low-frequency sensorineural hearing loss, whereas 12 subjects (19 ears) having notch-shaped high-frequency sensorineural hearing losses were examined in the second experiment. The results indicated that thresholds obtained from the rising portion of the audiometric configuration were, in most instances, determined by sensitivity at test frequency. An exception to this generalization involved low-frequency sensorineural hearing loss with a slope for the rising portion of the audiogram exceeding -25 dB/octave. In these cases the severity of the loss may be underestimated for test frequencies immediately adjacent to the rising portion of the audiogram.

Intelligibility of time-compressed sentential stimuli.

Time-compressed monosyllables have been studied relative to the assessment of central auditory disorders. In certain instances, sentential stimuli may be more useful than word lists in central auditory testing, particularly when results may be contaminated by concomitant peripheral hearing losses. Central Institute for the Deaf (CID) and Revised CID sentence lists and a contrived sentential approximation task were presented to 96 normal hearing young adults at time-compression ratios of 0%, 40%, 60%, and 70%, under sensation levels of 24 and 40 dB. The CID and RCID stimuli were more intelligible than the sentential approximations. The results are presented and discussed as they pertain to central auditory testing and are compared to earlier data using consonant-nucleus-consonant monosyllabic stimuli.

Unexplained conductive hearing loss.

We report a series of unusual clinical cases which exhibit what we have referred to as unexplained conductive hearing loss. Audiometrically, these cases typically display mild to moderate conductive or mixed-type hearing loss and good word discrimination (80% to 100%). The otologic evaluations also lend support to the audiometric findings. When polytome roentgenograms were obtained thr results showed a normal inner ear system. Most often, the otologists' clinical impression was a fixed malleus or congenital stapes fixation, and exploratory tympanotomy with inspection of the ossicular chain was recommended. In each case, the ossicular chain was found to be intact. When the incudostapedial joint was separated the malleus and incus were seen to be mobile. Further, palpation of the stapes resulted in good round window reflexes. Possible explanations for this phenomenon are considered.

Glomus tumor of the middle ear: origin, symptomatology, and treatment.

The glomus tumor is considered to be the most common of all tumors that involve the middle ear. This report defines the glomus tumor and discusses the symptomatology of the tumor with respect to the various developmental courses it may follow. Forty clinical cases of glomus tumor are reviewed, with emphasis upon the incidence of the tumor and its symptoms, including the audiological manifestations noted in this series of cases. Current medical management of the glomus tumor recommends surgical removal of the lesion when possible; however, irradiation and embolization of the tumor may also be considered when its invasion into surrounding structures has been extensive. The pathology and its treatment may have marked temporary or permanent effects upon the hearing of the patient, and the importance of ongoing audiological management is therefore emphasized.