Supplements for Chapter 25
From Auditory Demonstrations CD (see discussion here):
Primary and secondary beats ("secondary beats" we call waveform beats)
Aural combination Tones
Very helpful discussion and "Physclips" about Tartini tones and related issues from Joe Wolfe and the University of New South Wales here.
From Why You Hear What You Hear....
We have already discussed the Shepard tone demonstration in Chapter 23. However we do not call this effect an "illusion", since it is a required consequence and desired response, given our pitch perception apparatus. Real illusions are unintended consequences of our perceptual mechanisms. Some of the most impressive auditory illusions have been uncovered by Prof. Diana Deutsch as UC San Diego,
Perhaps foremost among these is the Octave Illusion, in which two notes differing by and octave are alternately played, one to each ear. People vary dramatically as to what they actually hear, with few getting it correct, and most hearing wildly different things than is really happening. Earbuds or earphones are a necessity.
Does what we see affect what we hear?
Try this YouTube video, with eyes closed and with eyes open and looking at the video.
For checking that the squares A and B are really the same shade, copy this image and commence cutting and pasting the image till just the two squares remain: