Syllable evoked auditory late responses: Effects of noise onsets and noise types

Listening in noisy situations demands cognitive effort. Recently, we have shown that the Wavelet Phase Synchronization Stability (WPSS) of Auditory Late Responses (ALRs) represents an objective method to estimate mental load in auditory environments. In literature only a limited number of publications can be found which focus on the effects of noise types and noise onset effects using syllable evoked ALRs. The objective of the present work was to analyze the influence of different parameters, like white and babble noise as well as different noise onset times 50, 300, 1000ms and continuous noise conditions, on syllable evoked ALRs. Also, the analysis of the WPSS, as used in previous work, has never been applied to see such effects on the ALRs. We found that noise onset times of 300ms or larger showed a good separation of the ALR components. Furthermore, the analysis of the WPSS for different scales showed a clear identification of the N1 components. However, the best type of noise, and noise onset configuration depends on the specific application. For investigations related to auditory processing of speech, ecological noises are preferred because they could be used to mimic everyday listening situations.