Why do these sounds "Alias" - if that's the right word

[llatham]

Stupid question I should know the answer to, but don't...

 

So I've got PCM sounds and can pitch shift them.

 

Of course, they not only get lower, but longer when you pitch them down - especially with anything that's like a rhythmic pattern (always fun to play a 5th and get 3 against 2 or whatever).

 

So I was playing with some drum sounds - snare goes down sounds like thunder/explosion. Good enough.

 

But when I went up, after a certain point, the sounds "reverse" - I mean like literally the audio file is backwards.

 

Now I've encountered deals where you keep going up a keyboard really high and the pitches either drop ridiculous octaves or start descending while still going up the keys.

 

But this seems a little different because it's like the sample is being played backwards like reversed audio in a DAW.

 

I mean, it's actually kind of cool because I can actually take a crash cymbal, raise the pitch and get a sound that's like your typical reverse crash.

 

But what's happening - did Nyquist forget to tell me something?

 

Are these samples too low of a bit rate? What gives?

[marczellm]

My Roland JUNO-G does that. I guess the engineers just decided to save the reverse sample into the high regions of the multisample, deeming it more useful.