Subject: Re: comparison of vision and auditory system From: Richard Lyon <dicklyon(at)ACM.ORG> Date: Fri, 30 May 1997 09:38:36 -0700>Jont Allen <jba(at)RESEARCH.ATT.COM> wrote: >> ... The frequency JND is very small, but the acuity of temporal events >> is suprisingly bad. I find this point cited often, but the notion of temporal events is not usually clearly pinned down in the discussion. For low-level temporal events, such as waveform peaks as resolved by the cochlear filtering, the auditory system has an amazingly precise ability to represent time. Binaural comparison of event times has JND around 10 to 20 MICROseconds. Monaural detection of displaced pulses in regular click trains is not much worse. Generally, the time JND for low-level events is much better than the reciprocal of the frequency JND for sine waves--as opposed to "suprisingly bad." For higher-level events, such as separately perceived sounds, or gaps in speech, the time JND is indeed much larger. But I don't see why that is surprising, as there's no reason to expect these higher-level processes to response on the same scale as the low-level sound detection levels of the auditory nervous system. They respond on a scale appropriate to the kinds of events that they extract. Dick