What to do about PCM buffer in voice changer

Question

Hi All,

I am trying to write a voice changer for android and I'm running in to some design decisions which I need a little help with.

I am using AudioRecord to get PCM audio from the mic, I need to record audio until the audio is below a certain level, I am then going to perform some processing on it and play it back. So I am unsure how long the audio is going to last for.

Since I want the delay between recording and playback to be as small as possible, I am unsure whether to keep the buffer in memory or to write it to the SD card and process it from there.

How much of a delay would using files induce when I am doing a lot of processing on the signal?

I am sampling at 8000 Hz so presumably 1s of audio would take up 1.6K of memory, what's the practical limit on the amount of memory I can use within the app?

Thanks