A simple word-recognition task in multitalker babble for clinic use was developed in the course of four experiments involving listeners with normal hearing and listeners with hearing loss. In Experiments 1 and 2, psychometric functions for the individual NU No. 6 words from Lists 2, 3, and 4 were obtained with each word in a unique segment of multitalker babble. The test paradigm that emerged involved ten words at each of seven signal-to-babble ratios (S/B) from 0 to 24 dB. Experiment 3 examined the effect that babble presentation level (70, 80, and 90 dB SPL) had on recognition performance in babble, whereas Experiment 4 studied the effect that monaural and binaural listening had on recognition performance. For listeners with normal hearing, the 90th percentile was 6 dB S/B. In comparison to the listeners with normal hearing, the 50% correct points on the functions for listeners with hearing loss were at 5 to 15 dB higher signal-to-babble ratios.

The purpose of this experiment was to determine the relationship between psychometric functions for words presented in multitalker babble using a descending presentation level protocol and a random presentation level protocol. Forty veterans (mean = 63.5 years) with mild-to-moderate sensorineural hearing losses were enrolled. Seventy of the Northwestern University Auditory Test No. 6 words spoken by the VA female speaker were presented at seven signal-to-babble ratios from 24 to 0 dB (10 words/step). Although the random procedure required 69 sec longer to administer than the descending protocol, there was no significant difference between the results obtained with the two psychophysical methods. There was almost no relation between the perceived ability of the listeners to understand speech in background noise and their measured ability to understand speech in multitalker babble. Likewise, there was a tenuous relation between pure-tone thresholds and performance on the words in babble and between recognition performance in quiet and performance on the words in babble.

Data from earlier studies that presented 70 words at 24 to 0 dB signal-to-babble (S/B) ratios indicated that most young listeners with normal hearing required 0 to 6 dB S/B ratios to attain 50% correct word recognition. Older listeners with hearing loss often required a >12 dB S/B ratio to attain 50% correct word recognition. In our study, we converted the Words in Noise test from one 70-word list into two 35-word lists for quicker administration by clinicians. Using baseline data from previous studies, we used two strategies to randomize the 35-word lists: based on recognition performance at each S/B ratio and based on recognition performance only. With the first randomization strategy, the 50% correct word-recognition points on the two lists differed by 0.5 dB for 72 listeners with hearing loss. With the second randomization strategy, 48 listeners with hearing loss performed identically on the two lists.

This study compares, for listeners with normal hearing and listeners with hearing loss, the recognition performances obtained with digit-pair and digit-triplet stimulus sets presented in multitalker babble. Digits 1 through 10 (excluding 7) were mixed in approximately 1,000 ms segments of babble from 4 to -20 dB signal-to-babble (S/B) ratios, concatenated to form the pairs and triplets, and recorded on compact disc. Nine and eight digits were presented at each level for the digit-triplet and digit-pair paradigms, respectively. For the listeners with normal hearing and the listeners with hearing loss, the recognition performances were 3 dB and 1.2 dB better, respectively, on digit pairs than on digit triplets. For equal intelligibility, the listeners with hearing loss required an approximately 10 dB more favorable S/B than the listeners with normal hearing. The distributions of the 50% points for the two groups had no overlap.