Using an adaptive strategy, the effects of mild sensorineural hearing loss and adult listeners' chronological age on speech recognition in babble were evaluated. The signal-to-babble ratio required to achieve 50% recognition was measured for three speech materials presented at soft to loud conversational speech levels. Four groups of subjects were tested: (1) normal-hearing listeners less than 44 years of age, (2) subjects less than 44 years old with mild sensorineural hearing loss and excellent speech recognition in quiet, (3) normal-hearing listeners greater than 65 with normal hearing, and (4) subjects greater than 65 years old with mild hearing loss and excellent performance in quiet. Groups 1 and 3, and groups 2 and 4 were matched on the basis of pure-tone thresholds, and thresholds for each of the three speech materials presented in quiet. In addition, groups 1 and 2 were similar in terms of mean age and age range, as were groups 3 and 4. Differences in performance in noise as a function of age were observed for both normal-hearing and hearing-impaired listeners despite equivalent performance in quiet. Subjects with mild hearing loss performed significantly worse than their normal-hearing counterparts. These results and their implications are discussed.

Previous investigations have established that, under identical test conditions, hearing-impaired listeners have more difficulty than normal-hearing listeners understanding speech in noise. Using an adaptive strategy, the effect of mild sensorineural hearing loss on speech recognition in babble was evaluated and the extent of the interaction of mild hearing loss with adult listeners' chronological age was examined. The signal-to-babble ratio required to achieve 50% recognition was measured for three speech materials presented at 56, 72, and 88 dB SPL; likewise, performance without babble was measured. Four sets of subjects (N = 18, each set) were tested: normal-hearing listeners <44 and >65 years of age, and hearing-impaired subjects <44 and >65 years. Subjects were selected so that age-group audiograms were closely matched. For results in babble, a consistent and statistically significant difference was demonstrated between the groups differentiated by age and by hearing loss, while only the latter effect was present in the absence of babble. Significant differences in articulation indices (AIs) between the two age groups were found for results in babble only, while no differences in AIs were seen between the two hearing loss groups under either listening condition. [Work supported by NINCDS.]

Although certain jobs could be affected, the gap between capacity and need is so great that automated audiometry will not significantly affect employment. Automation could increase the number of hearing impaired patients that could be served. The reallocation of personnel time would be a positive change for our patients and our profession.

This paper describes the results of two experiments in which speech recognition performance was determined for listeners with sensorineural hearing loss, while listening in babble. Adaptive strategies were used in both experiments to measure the signal-to-babble ratio required to achieve a preselected level of performance at several speech presentation levels encountered in normal conversation or when listening through an amplification system. The results suggest that the proposed adaptive strategy may provide a practical method by which the relative effects of competition on speech recognition may be quantified in an individual listener.

The auditory brain stem response to click stimuli was investigated in a group of 50 full-term healthy newborns, as well as in a group of 20 older children and adults. The stimulus parameters of click level and click repetition rate were varied systematically to quantify the characteristics of the auditory brain stem response in the full-term newborn infant. The results reveal increased latencies for waves I, III, and V for all conditions among the newborns, relative to the older age group. The results suggest that the neurological system is the primary source of differences between newborns and older subjects, but do not rule out the possibility that external ear, middle ear, or cochlear mechanisms may also contribute to the differences observed.