Automatic speed-loudness control

Hi. I’m looking for an automatic effect that will make an audio clip a bit slower and faster depending on how loud a particular section of audio is. Like, I’m looking for an effect that will slightly slow down the audio clip when the audio file plays a loud tone and speeds up as it gets quieter. (Eg. If the audio is: at -15db it will be fullspeed, at -10db is will be a little slower, at -6db it will be even slower, going back to -10 it will start speeding up again) Something that will have an adjustable Attack Time, Release Time, Threshold, and Ratio, just like a compressor. Image I hope I make sense to you guys, its kinda hard to explain. Through this, I’m trying to simulate: how an audio playback circuit (mostly used in digital toys) will slow down and speed up on a low battery depending on how much power/loudness is output to its speaker. With what I’m trying to do I’ll likely use 0.1 second attack, 1.0 second release, and threshold of approx -14 db

I’m not aware of any effects that do that, but if you feel ambitious, you could have a go at making a “Nyquist Plug-in” to do it (see:

Tritik Krush is a free plugin which works in Audacity which can simulate digital toys …

Krush does not follow envelope (which you specified): its effects are modulated by own LFO.