Fitting hearing aids to individual loudness-perception measures. 1996

T A Ricketts
Department of Speech Pathology and Audiology, University of Iowa, Iowa City, USA.

OBJECTIVE The purpose of this study was to compare the prescribed gain, compression ratios, compression thresholds, and the relative predicted speech intelligibility (Speech Intelligibility Index [SII], American National Standards Institute 3.79, proposed) provided by four strategies proposed for selecting hearing aid parameters for low-threshold compression hearing instruments and by a traditional threshold-based hearing aid fitting procedure. The strategies used were Desired Sensation Level Input/Output (DSLTM[i/o]; Cornelisse, Seewald, & Jamieson, 1994), Visual Input-Output Locator Algorithm (VIOLA; Cox, 1994), FIG6 strategy (Killion, Reference Note 2), Ricketts and Bentler strategy (RAB), and a threshold-based hearing aid fitting procedure (National Acoustics Laboratories-Revised [NAL-R]; Byrne & Dillion, 1986). These new strategies have been suggested as alternatives to threshold-based strategies, which do not provide the varying amounts of target gain, as a function of input level, necessary to fit low-threshold compression hearing aids. METHODS The electroacoustic prescriptions and the predicted speech intelligibility were calculated across all five fitting strategies for 20 subjects. The threshold and loudness growth information used for each fitting was reported previously (Ricketts & Bentler, in press). RESULTS Comparison across prescriptions revealed that the NAL-R strategy (due to the linear gain provided) prescribed the least gain for low-level inputs and the greatest gain for high-level inputs. Gain comparisons across fitting by loudness (FBL) strategies revealed a more shallow frequency response slope for strategies that require individual measures of loudness growth (RAB, VIOLA) in comparison with strategies that assumed average data (FIG6, DSLTM[i/o]). SII results revealed greater predicted speech intelligibility for the FIG6 and the DSLTM[i/o] compared with the NAL-R, RAB, and VIOLA. These differences were most apparent in noise backgrounds and least evident when loudness differences were minimized. CONCLUSIONS It appears that differences in SII scores across the FBL fitting strategies are due, in part, to differences in the loudness of the output signal. It is assumed that differences in high-frequency shaping may also be a factor. These data do not appear to support the use of additional clinical time to obtain individual loudness growth measures. However, due to the fact that SII results are based on average performance, it is difficult to predict whether differences across these fitting strategies would be realized in actual measures of speech intelligibility or sound quality on an individual basis.

UI MeSH Term Description Entries
D008144 Loudness Perception The perceived attribute of a sound which corresponds to the physical attribute of intensity. Loudness Perceptions,Perception, Loudness,Perceptions, Loudness
D012048 Correction of Hearing Impairment Procedures for correcting HEARING DISORDERS. Correction of Auditory Perception,Habilitation of Hearing Impairment,Hearing Impaired Rehabilitation,Rehabilitation of Hearing Impaired,Audiologic Habilitation,Audiologic Rehabilitation,Aural Habilitation,Aural Rehabilitation,Correction of Hearing Loss,Habilitation of Hearing Impaired,Rehabilitation of Hearing Impairment,Audiologic Habilitations,Audiologic Rehabilitations,Auditory Perception Correction,Auditory Perception Corrections,Aural Habilitations,Aural Rehabilitations,Habilitation, Audiologic,Habilitation, Aural,Habilitations, Audiologic,Habilitations, Aural,Hearing Impaired Habilitation,Hearing Impaired Habilitations,Hearing Impairment Correction,Hearing Impairment Corrections,Hearing Impairment Habilitation,Hearing Impairment Habilitations,Hearing Impairment Rehabilitation,Hearing Impairment Rehabilitations,Hearing Loss Correction,Hearing Loss Corrections,Impaired Habilitation, Hearing,Impaired Habilitations, Hearing,Impairment Correction, Hearing,Impairment Corrections, Hearing,Impairment Habilitation, Hearing,Impairment Habilitations, Hearing,Impairment Rehabilitation, Hearing,Impairment Rehabilitations, Hearing,Loss Correction, Hearing,Loss Corrections, Hearing,Perception Correction, Auditory,Perception Corrections, Auditory,Rehabilitation, Audiologic,Rehabilitation, Aural,Rehabilitation, Hearing Impaired,Rehabilitations, Audiologic,Rehabilitations, Aural
D006310 Hearing Aids Wearable sound-amplifying devices that are intended to compensate for impaired hearing. These generic devices include air-conduction hearing aids and bone-conduction hearing aids. (UMDNS, 1999) Ear Molds, Hearing Aid,Aid, Hearing,Aids, Hearing,Hearing Aid
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D013067 Speech Perception The process whereby an utterance is decoded into a representation in terms of linguistic units (sequences of phonetic segments which combine to form lexical and grammatical morphemes). Speech Discrimination,Discrimination, Speech,Perception, Speech
D017755 Prosthesis Fitting The fitting and adjusting of artificial parts of the body. (From Stedman's, 26th ed) Prosthesis Adjustment,Adjustment, Prosthesis,Adjustments, Prosthesis,Fitting, Prosthesis,Fittings, Prosthesis,Prosthesis Adjustments,Prosthesis Fittings

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