Source:mirv_snd_timescale - advancedfx/advancedfx GitHub Wiki
This command allows controlling the sound timescale independently of host_timescale.
This is useful in example used in the Smoother Demos guide.
Only Counter-Strike: Global Offensive is supported.
Forces the sound system to use the floating point value <fValue> as time scale. Note that this command will ignore the demo speed, unlike host_timescale.
Examples:
mirv_snd_timescale 1.0 // plays the sound in normal speed
mirv_snd_timescale 0.5 // plays the sound in half (50%) speed
mirv_snd_timescale 2 // plays the sound in twice the normal speed
mirv_snd_timescale 0 // mutes the audio
Makes the sound system use the default behaviour (so it will depend on host_timescale again):
mirv_snd_timescale default