Mishearing as a Side Effect of Rational Language Comprehension in Noise

Abstract

Language comprehension in noise can sometimes lead to mishearing, due to the noise disrupting the speech signal. Some of the difficulties in dealing with the noisy signal can be alleviated by drawing on the context - indeed, top-down predictability has shown to facilitate speech comprehension in noise. Previous studies have furthermore shown that strong reliance on the top-down predictions can lead to increased rates of mishearing, especially in older adults, which are attributed to general deficits in cognitive control in older adults. We here propose that the observed mishearing may be a simple consequence of rational language processing in noise. It should not be related to failure on the side of the older comprehenders, but instead would be predicted by rational processing accounts. To test this hypothesis, we extend earlier studies by running an online listening experiment with younger and older adults, carefully controlling the target and direct competitor in our stimuli. We show that mishearing is directly related to the perceptibility of the signal. We furthermore add an analysis of wrong responses, which shows that results are at odds with the idea that participants overly strongly rely on context in this task, as most false answers are indeed close to the speech signal, and not to the semantics of the context.

Keywords: aging; background noise; false hearing; mishearing; predictive context; speech comprehension.

Figure 1

This figure shows the different stages of the experiment, with a single trial between brackets. Participants completed four practice trials and sixty experimental trials.

Figure 2

This figure shows the participant’s answers; split for target and distractor items, with age plotted on the x-axis and answer type on the y-axis. Here 0 denotes the distractor response and 1 the target response. Different line colors show different noise conditions. The different plots show the high (HP)- and low-predictability (LP) items for stimuli differing in a plosive (P) or vowel (V).

Figure 3

This figure shows the wrong responses that semantically fit or did not fit the sentence, plotted with the normalized phonetic distance, in each of the three noise conditions. Lower phonetic distance means more similar to the target item. A distance of 1 means an empty response.

Figure 4

This figure shows the participants’ confidence ratings; split for the predictability conditions, with HP at the top row and LP at the bottom, as well as the three answer types. Age plotted on the x-axis and confidence on the y-axis. Here 1 denotes the lowest confidence and 1 the highest confidence. Different line colors show different noise conditions.