Pitch change - not the doppler effect

[AndiFlatland]

I've noticed that when I'm listening to music on my earphones, when I remove them, the pitch of the music I can still hear from the earphones changes downwards by about a semitone. When my earphones are connected to the hi-fi, the music still comes out of the speakers, and the pitch change also occurs in this instance - the music coming from the speakers seems to be about a semitone lower than in the earphones.
This cannot be due to the doppler effect, as this is only noticeable at high speeds, such as when a police car siren passes you in the street. The speed of removal of my headphones is nowhere near as fast as that!
What's going on here, then?

[rojash]

The second two boxes on this page may help to explain the *apparent* change in pitch.
http://hyperphysics.p...base/sound/pitch.html

[ABerrant]

As an aside, the constant speed required for the aforementioned police car to pass an observer for there to be a perceived (Doppler) semitone pitch change of the siren's approach and retreat is around 11mph.

[ABerrant]

oops! typo... speed should read 22mph

[jomifl]

Interesting Rojash,I just did a little experiment on a string instrument and found that I can distinguish a change of pitch of one tenth of a semitone, so it would only need a tiny change in apparent or real pitch to give a doppler effect, It is possible that removing the headphones may change their acoustics with the removal of the resonant cavity between the headphone diaphragm and the ear.

[rojash]

A 10 cent variation (which is a 10th of a semitone) should be audible to most people, depending on the timbre of the sound. But the psycho-acoustic change due to variation in sound level is not related to the Doppler effect, which is purely physical and caused by the sound wave being compressed (and the thus the wavelength shortened and the frequency raised) when a sound source is approaching the listener (and of course vice versa). This of course applies to any wave propagation, not just sound. (for example the red and blue shift of light).