Can anyone explain in terms of notes and scales why Middle Eastern music sounds "sour" to western ears?

Answer 1

Channel 4 have just started a series by Howard Goodall called "How Music Works" which actually deals with this type of question. (see link attached).

Very basically the keys and scales that we are used to in the West mean that our ears (brain) expect to hear sequences of notes separated by a certain amount of pitch - in the West the smallest interval of pitch is a semitone.

Other cultures, use different keys and scales where the pitch intervals may be different.

As we, in the West, are attuned to hearing a specific pitch interval, when this doesn't occur (as is sometimes the case with Eastern music) then we regard it as "atonal"............or "sour" as you put it.

Answer 2

The above post is part of the answer. The reason is predominantly that Middle Eastern music uses intervals of pitches that are smaller than would be used in western music. There are only twelve notes in one octave in western music. In Eastern music there are many, many more. These smaller pitches sound like an instrument that is out of tune, to western ears.