885095942

2:30-2:45

Break

2:45

7PP5. Normal hearing levels for an ER-3A insert earphone. Michael J. Vavrek and Tom Frank (Dept. of Conimun. Disord., 5-A Moore, Penn Stale Univ., Univcrsity Park, PA 16802)

Equivalent threshold sound pressure Icvels were obtuined on each ear of 48 normal hearing adult subjects from 125-8000 Hz using TDH-49P earphones, referenced to a NBS-9A coupler, and ER-3A insert earphoncs, referenced to a HA-2 coupler. At each frequency (N =9), the thresholds were significantly higher for the TDH-49P than for the ER-3A; however, the test versus retest and right versus left ear thresholds were not significantly diffcrent. The unadjustcd ER-3A thresholds were in agreement with the reference equivalent threshold sound pressure levels (RETSPLs) reported by ISO [ISO 389, DAD 3, 1990]. After correcting for the subject‘s deviation from normal TDH-49P hearing levels and coupler (HA-2 to HA-1), the F.R-3A thresholds were also in agreement with interim RETSPLs reported by ANSI [ANS1 S3.6-1989, Appcndi* G]. A complcte data basc conccrning normative ER-3A thresholds will be presented and discussed in reference to the results of the present study, ISO and ANSI RETSPLs, and for futurę standard-ization.

3:00

7PP6. Low- and high-frequency threshold reliability. Laura E. Dreisbach and Tom Frank (Dept. of Commun. Disord., 5-A Moore, Penn State Univ., University Park, PA 16802)

The purpose of this study was done to dctcrmine intrasubjcct low-and high-frequency hearing threshold reliability. Low-frequency (1, 4, 8 kHz) and high-frequency (10, 12, 14, 16, 18 kHz) thresholds were obtained on each ear of 30 normal hearing young adult subjects over four trials separated by I but no morę than 2 weeks using a Beltone 2000 audiometer. At each frequency, the thresholds were not significantly diflferent for the first vcrsus second car tested or for the four trials. Between trial threshold differences for each possible trial minus trial threshold combination (N = 6) were determined for each ear of each subjcct at each frequency. For the possible 2880 between trial threshold comparisons (6 trial combinations X 8 frequencics X 30 subjects X 2 ears), only 23 resulted in threshold differences >±11 dB. It was con-cludcd that repeated intrasubjcct high-frequency thresholds were as re-liable as for the lower frequencies. Clinical implications regarding high-frequency serial monitoring of hearing thresholds will be discussed.

3:15

7PP7. MacCAD, a new Macintosh-based HyperCard program for central auditory diagnostics: Description and preliminary findings. Judith L. Lauter, Nancy Solomon, and Colette Coe (Dept. of Speech and Hear. Sci., Univ. of Arizona, Tucson, AZ 85721)

Although most components of the classical auditory system lie be-twcen the pcriphcry and association cortex, our information about au-ditory disorders is limited primarily to those extremes. This ignorance is due to the fact that until recently, appropriately sensitive methodolo-gies, both in terms of test design as well as modes for noninvasive brain monitoring, have not been readily available in the clinic. MacCAD is an attempt to address the first of these issues; a companion paper will report on results combining MacCAD with noninvasive physiological testing [repeated evoked potcntials (REPs)]. MacCAD brings features of basic-research test design into the clinic, including: ease of use by both tester and client, monaural and dichotic modes for a variety of speech and nonspeech sounds, cxpansion capability for additional sounds, graduated difficulty for each sound set, client control of test pacing, automatic stimulus/response recording, trial-by-trial feedback, and analysis options including trial-by-trial monitoring, confusion ma-trices, and percent correct for individual sounds and complete sets. Initial field testing with populations predicted to have damage between periphery and language cortex, including adults with central auditory dysfunction, multiple sclerosis, Parkinson’s disease, and presbyacusis, indicates that MacCAD’s unique features may render it sensilive to individual characteristics which, when interpreted in the context of results on other lests such as evokcd potentiaLs, may be indicative of auditory dysfunctions which are invisible to standard audiological testing. [Work supported in part by Apple Computer, Inc., Community Affairs, with the American Speech-Language-Hearing Foundation.]

3:30

7PP8. MacCAD and REP/ABRs: A new test battery for central auditory dysfunction. Judith L. Lauter and Janiece Lord-Maes (Dept. of Speech and Hear. Sci., Univ. of Arizona, Tucson, AZ 85721)

Traditionally, audiologists have specialized in the peripheral hearing system. However, recent advances in the diagnosis and treatment of peripheral problems, together with developmcnts in brain imaging, sug-gest that the futurę of audiology is in the brain, focusing on dysfunctions resulting from CNS pathology. Financial realities dictate that the first steps toward this new futurę emphasizc techuologies which are already available and/or reasonably priced. I wo components of a test battery based on these principles havc been developed in our laboratories. A companion paper describes MacCAD, a Macintosh-bascd program for monaural/dichotic testing of speech and nonspeech sounds, which can be run on a Macintosh SE/30 with no additional hardware. Second, a simple repeated-measures modification of evoked-potential testing [repeated evoked potcntials (REPs)] applied to auditory brainstem re-sponses (ABRs) yields a dramatic inerease in sensitivity to individual characteristics, based on standard EP equipment and procedures. Pilot testing with a combination of these two tests suggests that the two-part battery is not only sensitivc to individual characteristics of central auditory function, but may also rcveal striking correlations between the results on each test, such that details of an individual’s performance on one may predict specific details observed with the other. Thus the combination of the two tests can provide complementary behavioral/ physiological documentation of underlying dysfunction which may be invisible to convcntional testing. In those cases where testing is available on morę expensive brain-monitoring tooLs such as MRI, qEEG, and PET, this battery could also serve as a basis for hypothesis formulation, thus rendering their use morę cost-effective.

1975 J. Acoust. SOC. Am.. Vol. 89, No. 4, Pt. 2. Aprif 1991

121 st Meeting. Acouslical Society of America 1975