Aging and the effect of target-masker alignment

Abstract

Similarity between target and competing speech messages plays a large role in how easy or difficult it is to understand messages of interest. Much research on informational masking has used highly aligned target and masking utterances that are very similar semantically and syntactically. However, listeners rarely encounter situations in real life where they must understand one sentence in the presence of another (or more than one) highly aligned, syntactically similar competing sentence(s). The purpose of the present study was to examine the effect of syntactic/semantic similarity of target and masking speech in different spatial conditions among younger, middle-aged, and older adults. The results of this experiment indicate that differences in speech recognition between older and younger participants were largest when the masker surrounded the target and was more similar to the target, especially at more adverse signal-to-noise ratios. Differences among listeners and the effect of similarity were much less robust, and all listeners were relatively resistant to masking, when maskers were located on one side of the target message. The present results suggest that previous studies using highly aligned stimuli may have overestimated age-related speech recognition problems.

FIG. 1.

Composite audiograms for the middle-aged and older groups. Dotted and dashed lines represent one standard deviation from the mean of obtained thresholds for the right and left ear, respectively.

FIG. 2.

Schematic depiction of the target and maskers during aligned and non-aligned trials.

FIG. 3.

Percent-correct performance on the speech recognition task averaged across the five scored words in each sentence. Error bars show the standard error.

FIG. 4.

(Top) Effect of alignment on speech recognition performance. Reported values were calculated as percent-correct in the non-aligned masker condition minus percent-correct in the aligned masker condition. Error bars show the standard error. (Bottom) Effect of spatial configuration of maskers on speech recognition performance. Reported values were calculated as percent-correct when maskers were on one side minus percent-correct when maskers were symmetric around the target. Error bars show the standard error.

FIG. 5.

Word-by-word analysis of responses for each word in the target sentences for data collected at −6 dB SNR in the symmetric (RL) masker condition. Error bars show the standard error.

FIG. 6.

Error patterns produced by participants in the symmetric masking condition at −6 dB SNR. Values represent the proportion of each error type relative to all errors.