Subject: Minor third From: Christian Kaernbach <auditory(at)KAERNBACH.DE> Date: Sat, 29 Jan 2005 09:46:31 +0100Dear List, In a very speculative way one could assume that one reason for minor-third calling is to avoid possible masking by unexpected environmental sounds. Assuming that many environmental sounds have a spectrum varying strongly as a function of frequency (that is with the amplitude in one frequency band not correlated strongly to the amplitude in other frequency bands) it would be advisable to code your message such that it involves two different frequency bands so that if one of these two bands is masked only half of the message is lost. That would be better than a 50% chance that the entire message is lost because speech is redundant, and because the recipient might solicit a resend of the message. Al argues that small intervals are favorable for coherence, so the task is to find the smallest interval that grants the involvement of two different frequency bands. The width of frequency bands in human hearing is a third of an octave, i.e. a major third. From this reasoning it would follow that third-calling would better make use of major thirds than of minor thirds. But then: how could our ancestors know the width of frequency bands with semitone precision long before Fletcher :-? Best, Christian Kaernbach www.kaernbach.de Al Bregman replied to Jeremy Day-O'Connell: Regarding the second point, I would imagine that the opposite would be true: the larger the interval, the more difficult it would be to track the sequence in a noisy real-world situation. Small intervals favor coherence; in an A-B sequence, the larger the interval between A and B (i.e., the smaller the similarity between them), the greater the likelihood that one of the sounds (A or B) will find a more similar sound to group with than the other sound of the A-B sequence. This means that BOTH the vocal ease and the perceptual coherence would favor small intervals.