Perception of frequency-dependent processing delays motivated by hearing devices.

Processing delays can negatively affect listening experience, especially in cases where the (processed) delayed sound interferes with an un-delayed (or direct) sound component, as it is the case for (open-fit) hearing devices. In this study, psychometric functions for delay perception in individual frequency bands were measured. Also, it was assessed how noticeability adds up across frequency bands for frequency-dependent processing delays. Noticeability of delays depends largely on the phase shift they introduce in each frequency band. Psychometric functions are non-monotonous, with maximum noticeability at phase shifts (2n+1)π. When using the sensitivity index d' to describe the noticeability of a delay, the overall noticeability dtotal' of a frequency-dependent delay was found to be the RMS of the noticeabilities dn' in each frequency band n. Additionally, different auditory models were tested regarding their capability to predict the experimental results. The audio quality model GPSMq [Biberger et al. (2018). J. Audio Eng. Soc. 66(7), 578-593] showed the best performance for the majority of conditions, yielding predictions that are highly correlated (ρ>0.85) with the participants' results. Model performance could confirm that delays are mainly perceived based on spectral effects.