Audio playback controls greyed out after changing sample rate to 520 Hz

Question

For educational purposes, I modified my Audition session file to change the sample rate to 520 Hz (around the sample rate of a low-end AM radio broadcast) as part of an effort to emulate the sound of an old radio broadcast. I was able to drag an audio clip into the first track (which After Effects automatically resampled to 520 Hz for me), but I was not able to play it back, as all playback controls were disabled for some reason. How do I fix this? It is an absolute requirement that I use a low sample rate for this project (not really, I'd just prefer to do it that way).

SteveG_AudioMasters_ · Answer

I don't think that there's a sound device around that will run that slowly! Even though you can get software to change sample rates to almost anything you choose, it doesn't mean that the hardware has to follow this. Most devices have limits well higher than 520s/sec.

But let's have a look at this. Your average AM radio broadcast has a defined spectrum space of 10kHz in N.America (9kHz rest of the world) and this limits, in the worst case, the audio bandwidth of your modulated signal to 4.5kHz without causing out-of-band splash (which gets you in trouble with the authorities). To set a sample rate that would allow sounds up to 4.5kHz only to be digitised it would have to be twice the audio bandwidth - so 9ks/sec which will give you a Nyquist limit of 4.5kHz

Your sample rate of 520s/sec would give you an audio bandwidth of 260Hz - you would only hear rumbling noises! I think you need to reconsider this...

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