Minor thirds and background noise

[Brian Gygi <bgygi@xxxxxxxxx>]

In general, environmental sounds have a 1/f spectrum, which was the subject
of much discussion on this list a couple of years ago.  However, the
spectral shape of an individual instance of masking background can vary
widely, from speech-shaped noise to broadband noise or, theoretically, even
harmonic (say, if you were sitting in the middle of a horn section).

At 12:46 AM 1/29/2005, Christian Kaernbach wrote:
> Dear 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.