[J65nko]

#!/bin/sh
# play soundfile after certain amount of time
# using OpenBSD 'aucat(1)' 

SOUNDFILE="/home/j65nko/thesilentforce/track01.wav"

while true ; do
    printf "Time to wait (mm:ss) = "
    read time
    #time='0:10'
    minutes=${time%:*} 
    seconds=${time#*:}
    pause=$((minutes*60+seconds))
    echo "Waiting $time (${pause} seconds) ...."
    sleep ${pause}
    echo =======================
    echo Playing ${SOUNDFILE}
    aucat -i $SOUNDFILE
    echo ======================
done

A sample run, where I terminate the loop with Control-C:

$ ./alert-me

Time to wait (mm:ss) : 37:00
Waiting 37:00 (2220 seconds) ....
=======================
Playing /home/j65nko/thesilentforce/track01.wav
======================
Time to wait (mm:ss) =  ^C