Effects of energetic and informational masking on interactive speech communication in younger and older adults

Our ability to communicate successfully with others can be strongly affected by the presence of noise and other voices in the environment, and older adults (OAs) can be more greatly affected than young adults (YAs) in these situations. The interference (or masking) that is caused by one sound on the perception of another depends on the characteristics of the masker: whether energetic (EM) or informational masking (IM, e.g., speech-on-speech masking), and the weighting between the effects of EM and IM can vary with the age of the listener, some studies showing increased effect of IM in older adults. However, these results are mostly based on perception tests using simple pre-recorded sentences that are void of communicative intent and, therefore, less representative of our everyday communicative situations.

The focus of this study is to investigate the impact of EM and IM on interactive speech communication between groups of YA and OA talkers. We audio record pairs of normally hearing YA and OA female talkers (18-30 and 55-75 years; N=30) while they carry out a “spot-the-difference” picture description task (diapix) with another volunteer from the same age range. The picture task is carried out in four listening conditions affecting both participants: both speakers in i) quiet, ii) IM that is semantically related to the picture description task iii) IM that is semantically unrelated to the task (both 3-talker maskers: male, female and a child), and iv) EM (speech-shaped-noise, SPSN, for the male, female and a child talker). To simulate acoustics in real rooms, we use real-time virtual audio environment software (www.phon.ucl.ac.uk/resource/audio3d/) with spatially separated sound sources, for each of the three talkers in the maskers, presented over headphones (at 72 dB in the noise conditions). To assess the impact of EM/IM on communication we measure i) communication efficiency (time it takes to find differences in the picture task) and ii) speaking effort (acoustic-phonetic features of their speech: f0 median, mean energy in 1-3 kHz range, articulation rate). We expect greater difficulty (less efficient communication, more effort) in adverse conditions by OA talkers, with greatest difficulty imposed by task-relevant IM condition. In order to assess if communication efficiency in noise is influenced by differences in cognitive factors between YA and OA talkers, such as selective attention, we measure distractibility via a secondary go/no-go auditory detection task, and expect secondary task accuracy to be associated with task performance in older talkers.