Returns a percentage value for use with scripts that play sounds on the Mac

getsuggestedvolume.sh

#!/usr/bin/env zsh

# Usage:
# Source this and then use the function with afplay
# afplay -v $( getsuggestedvolume ) foo.wav
function getsuggestedvolume() {

	(( systemVolume=$(osascript -e 'output volume of (get volume settings)') ))
	(( currentVolume=`echo "scale=2; $systemVolume/100" | bc -l` ))
	(( normalizedVolume=`echo "scale=2; $currentVolume/3" | bc -l` ))
	(( maxVolume=0.33 ))

	printf "%.2f" $(( $normalizedVolume<=$maxVolume?$normalizedVolume:$maxVolume ))
}