Effects of noise type on listening effort: relationship between subjective ratings and objective measurements

The present study investigates the relationship between the self-rated effort when listening to speech in adverse conditions, and response time, taken as a measure of the cognitive resources deployed for interpreting and responding to the auditory stimulus. Specifically, the peculiar effects of two background noises are assessed: a steady state, speech-shaped noise (SSN) and a fluctuating (ICRA) masker. Matrixed-word listening tests were proposed to a panel of young adults with normal hearing. Twelve realistic acoustic conditions were created by varying speech and noise levels, reverberation and noise type. For each condition intelligibility scores (IS), response time (RT) and self-rating of listening effort were collected. The results were mapped by using the objective short-term metric STIr, whose run-time nature allows the tracking of non-stationary maskers, properly accounting for “listening in the gaps”. Even though the same accuracy was achieved in the two maskers, the conditions with ICRA noise were always rated as more effortful; similarly, RT was significantly higher in fluctuating noise, revealing a greater engagement of cognitive resources.