changing radio volume

[Fluid]

I use the cheat floatProp tvVolume in my userstartup.cheat file to control the volume of the television.

Is there a similar cheat for controlling the volume of the radio?

Or, would you have to change the radios themselves?

I know that you can adjust the volume of the radio under the audio options, but that changes other music options also. I'm looking for a way to change only the radio volume.

Thanks