Subject: Re: brightness From: beauchamp james w <j-beauch(at)UX1.CSO.UIUC.EDU> Date: Fri, 10 May 2002 20:18:50 -0500Chen-Gia Tsai wrote: > I am interested in analogues between visual and auditory processing. > > We describe sounds rich in high-frequency harmonics "bright". This adjective > is apparently universal. Why do we use such a visual concept to describe an > auditory feature? (snip) Here's an idea. For whatever reasons, we seem to associate high frequencies with physical height, perhaps because high frequencies travel in straight lines and they tend to transmit at some height whereas low frequencies can creep and crawl over terrain. Or maybe because a lot of birds make high pitches but big animals that hug the ground make low pitches. Now, the sun is also high and very bright, and we look up to see the sun. So we look up to see the sun and we point our ears up to hear high frequencies, and thus we may associate height with increased brightness, and thus high frequencies with increased brightness. If there are a lot of strong high frequencies in a sound, we will hear "higher" and thus it will sound brighter. This is just a conjecture; there's nothing rigorous about it. Several researchers have found the spectral centroid, which correlates strongly with "brightness" or "sharpness" verbal attributes, to be an important, perhaps the most important, single characteristic for distinguishing amongst sound spectra. See for example, von Bismark, G. (1974). "Sharpness as an attribute of the timbre of steady sounds", Acustica, 30(3), pp. 159-172. Jim Beauchamp University of Illinois at Urbana-Champaign