note2freq(){
	local freq
	case $1 in 
		A[1-7])
			case $1 in 
				*1) freq=55;;
				*2) freq=110;;
				*3) freq=220;;
				*4) freq=440;;
				*5) freq=880;;
				*6) freq=1760;;
				*7) freq=3520;;
			esac
			;;
		Bb[1-7]|As[1-7])
			case $1 in 
				*1) freq=58;;
				*2) freq=117;;
				*3) freq=233;;
				*4) freq=466;;
				*5) freq=932;;
				*6) freq=1865;;
				*7) freq=3729;;
			esac
			;;
		B[1-7])
			case $1 in 
				*1) freq=62;;
				*2) freq=124;;
				*3) freq=247;;
				*4) freq=494;;
				*5) freq=988;;
				*6) freq=1976;;
				*7) freq=3951;;
			esac
			;;
		C[1-7])
			case $1 in 
				*1) freq=33;;
				*2) freq=65;;
				*3) freq=131;;
				*4) freq=262;;
				*5) freq=523;;
				*6) freq=1047;;
				*7) freq=2093;;
			esac
			;;
		Cs[1-7]|Db[1-7])
			case $1 in 
				*1) freq=35;;
				*2) freq=69;;
				*3) freq=139;;
				*4) freq=277;;
				*5) freq=554;;
				*6) freq=1109;;
				*7) freq=2217;;
			esac
			;;
		D[1-7])
			case $1 in 
				*1) freq=37;;
				*2) freq=73;;
				*3) freq=147;;
				*4) freq=294;;
				*5) freq=587;;
				*6) freq=1175;;
				*7) freq=2349;;
			esac
			;;
		Ds[1-7]|Eb[1-7])
			case $1 in 
				*1) freq=39;;
				*2) freq=73;;
				*3) freq=147;;
				*4) freq=294;;
				*5) freq=587;;
				*6) freq=1175;;
				*7) freq=2349;;
			esac
			;;
		E[1-7])
			case $1 in 
				*1) freq=41;;
				*2) freq=82;;
				*3) freq=165;;
				*4) freq=330;;
				*5) freq=659;;
				*6) freq=1319;;
				*7) freq=2637;;
			esac
			;;
		F[1-7])
			case $1 in 
				*1) freq=44;;
				*2) freq=87;;
				*3) freq=175;;
				*4) freq=349;;
				*5) freq=699;;
				*6) freq=1397;;
				*7) freq=2794;;
			esac
			;;
		Fs[1-7]|Gb[1-7])
			case $1 in 
				*1) freq=46;;
				*2) freq=93;;
				*3) freq=185;;
				*4) freq=370;;
				*5) freq=740;;
				*6) freq=1480;;
				*7) freq=2960;;
			esac
			;;
		G[1-7])
			case $1 in 
				*1) freq=49;;
				*2) freq=98;;
				*3) freq=196;;
				*4) freq=392;;
				*5) freq=784;;
				*6) freq=1568;;
				*7) freq=3136;;
			esac
			;;
		Gs[1-7]|Ab[1-7])
			case $1 in 
				*1) freq=52;;
				*2) freq=104;;
				*3) freq=208;;
				*4) freq=415;;
				*5) freq=831;;
				*6) freq=1661;;
				*7) freq=3322;;
			esac
			;;
		*)
			printf "ERROR: Unknown note: \"%s\"
Valid note syntax: <letter>[accidental]<octave>

Valid values:
	<letter>	\"A\" through \"G\"
	[accidental]	\"b\" (flat), or \"s\" (sharp)
			Exceptions: \"Bs\", \"Cb\", \"Es\", and \"Fb\" are not valid.
	<octave>	\"1\" through \"7\"
" "$1"
			return
	esac
	printf "%s" "$freq"
}

sing() {
	local beepstring
	while [ "${3+defined}" ]; do
		if [ "$3" = "-n" ]; then
			beepstring="$beepstring -f $(note2freq $1) -l $2 -n"
			shift 3
		else
			echo "Error"
			return
		fi
	done
	if [ -z "$3" ]; then
		beepstring="$beepstring -f $(note2freq $1) -l $2"
		beep $beepstring
	fi
}