At 10:41 09/02/2016, Michael Shields wrote:
>The discussion about perception of fragments of a sound wave made me 
>wonder how short a note can still be and have a perceivable pitch 
>(for example, a simple wave played loud at 440Hz).  It appears the 
>pragmatic answer is that pitch perception starts when sounds are 
>about 100 milliseconds or longer, with higher pitches being 
>perceptible at considerably shorter bursts (at least in theory).... 
>If one takes 1/10 second as a guide minimum length, that would mean 
>that at 440Hz one hears 44 cycles before recognising pitch.

True for pure tones (if they exist in the real world, because that 
would assume perfect transducers). As far as music is concerned, 
every note that is played has harmonics, and even if there is not 
enough of a pure tone component for 440Hz is recognisable, there may 
be enough cycles of the harmonics for them to be distinguished, and 
the ear (or the brain) will understand that there is a 440 fundamental there.

At lower frequencies, when it is too expensive to equip an organ with 
a full set of 32' pipes, they can be simulated by a 16' plus pipes at 
the interval of a fifth which creates the harmonics that a 32' would 
have produced, and the listener 'hears' the 32' which is not there. 
The way that this works is sometimes misunderstood, see 
http://www.pykett.org.uk/resultantbass.htm

David Hitchin 

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