The Performance-Perceptual Test (PPT) and its relationship to aided reported handicap and hearing aid satisfaction

Results of objective clinical tests (e.g., measures of speech understanding in noise) often conflict with subjective reports of hearing aid benefit and satisfaction. The Performance-Perceptual Test (PPT) is an outcome measure in which objective and subjective evaluations are made by using the same test materials, testing format, and unit of measurement (signal-to-noise ratio, S/N), permitting a direct comparison between measured and perceived ability to hear. Two variables are measured: a Performance Speech Reception Threshold in Noise (SRTN) for 50% correct performance and a Perceptual SRTN, which is the S/N at which listeners perceive that they can understand the speech material. A third variable is computed: the Performance-Perceptual Discrepancy (PPDIS); it is the difference between the Performance and Perceptual SRTNs and measures the extent to which listeners "misjudge" their hearing ability. Saunders et al. in 2004 examined the relation between PPT scores and unaided hearing handicap. In this publication, the relations between the PPT, residual aided handicap, and hearing aid satisfaction are described.

Ninety-four individuals between the ages of 47 and 86 yr participated. All had symmetrical sensorineural hearing loss and had worn binaural hearing aids for at least 6 wk before participating. All subjects underwent routine audiological examination and completed the PPT, the Hearing Handicap Inventory for the Elderly/Adults (HHIE/A), and the Satisfaction for Amplification in Daily Life questionnaire. Sixty-five subjects attended one research visit for participation in this study, and 29 attended a second visit to complete the PPT a second time.

Performance and Perceptual SRTN and PPDIS scores were normally distributed and showed excellent test-retest reliability. Aided SRTNs were significantly better than unaided SRTNs; aided and unaided PPDIS values did not differ. Stepwise multiple linear regression showed that the PPDIS, the Performance SRTN, and age were significant predictors of scores on the HHIE/A such that greater reported handicap is associated with underestimating hearing ability, poorer aided ability to understand speech in noise, and being younger. Scores on the Satisfaction with Amplification in Daily Life were not well explained by the PPT, age, or audiometric thresholds. When individuals were grouped by their HHIE/A scores, it was seen that individuals who report more handicap than expected based on their audiometric thresholds, have a more negative PPDIS, i.e., underestimate their hearing ability, relative to individuals who report expected handicap, who in turn have a more negative PPDIS than individuals who report less handicap than expected. No such patterns were apparent for the Performance SRTN.

The study showed the PPT to be a reliable outcome measure that can provide more information than a performance measure and/or a questionnaire measure alone, in that the PPDIS can provide the clinician with an explanation for discrepant objective and subjective reports of hearing difficulties. The finding that self-reported handicap is affected independently by both actual ability to hear and the (mis)perception of ability to hear underscores the difficulty clinicians encounter when trying to interpret outcomes questionnaires. We suggest that this variable should be measured and taken into account when interpreting questionnaires and counseling patients.