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Biomedical subjects

W J Ballad

Publications and source records attributed to W J Ballad.

5 recordsLinked to original sources
PubMed1995

Comparison of two hearing aid receiver-amplifier combinations using sound quality judgments.

Sound quality judgments were obtained on two binaural pairs of laboratory hearing aids with similar battery drain. One pair had a traditional low-current-drain "starved Class A" output stage. The other had a new (at the time) "Class D" output stage. Speech and music reproduction was rated, for seven input levels between 70 and 100 dB SPL, on an overall quality scale by juries of normal-hearing and hearing-impaired subjects. The same subjects also were asked to assign a dollar value to each condition by answering the question "What would you pay for a hearing aid that sounded like that?" Both subject groups rated the hearing aids with the Class D output stage as having superior sound quality across a variety of input levels and test materials, consistent with objective distortion measurements. On the average, each one-percentage point increase in sound quality rating corresponded to a $6.75 increase in perceived value in these experiments.

Adult↗
PubMed1986

Relative frequency of inferior vestibular schwannoma.

Until quite recently, acoustic tumors were not diagnosed until they had reached relatively large size. Vestibular function tests were positive in a large percentage of these cases. Since vestibular function tests are limited to lesions of the superior branch of the vestibular nerve, it was thought that 90% of vestibular schwannomas arose from the superior vestibular nerve. Recently, as the diagnostic efficiency of auditory tests has improved, many small tumors are being detected. As the size of the tumors decreases, the efficiency of vestibular function testing has also decreased. A review of histologic and surgical literature demonstrates that the earlier estimate is inaccurate, and that only 50% of vestibular schwannomas originate on the superior branch of the vestibular nerve. This warrants a critical review of the value of vestibular function tests in the evaluation of suspected vestibular schwannomas.

Cranial Nerve Neoplasms↗
PubMedDate not supplied

Clinical use of an insert earphone.

There are several applications of and advantages to using an insert earphone. An insert earphone has three parts: a transducer to convert electrical energy to sound, a conduit to deliver the sound into the ear canal, and a coupler connecting the device to the canal. The data from this study indicate that there is a distinct advantage in using insert earphones over TDH-49 phones (standard headphones) in the attenuation of low frequency ambient noise. The use of insert earphones will permit one to test hearing in areas of higher ambient noise than was previously possible. Insert earphones are used to shorten the hearing aid selection process. A technique is described in which only one real ear measurement is required for an accurate hearing aid fitting. Most, but not all, of the masking dilemmas that are encountered with standard headphones are circumvented or eliminated by using insert earphones. In brain stem auditory evoked response testing, the insert earphone reduces the stimulus artifact without influencing the acoustic signal. Finally, the insert earphone solves the collapsing ear canal problem.

Audiometry↗
PubMedDate not supplied

Monitoring of the glycerol test with sinusoidal harmonic acceleration in Menière's disease patients.

Changes in auditory pure tone threshold and speech discrimination and the phase and gain in the sinusoidal harmonic acceleration test were measured in subjects with endolymphatic hydrops (Meniere's disease) following the administration of glycerol. Although all subjects showed a marked improvement in auditory function, a comparable change in vestibular function, as measured by the sinusoidal harmonic acceleration test, was not observed.

Acceleration↗