The code used is wrong and has a syntax error.
Use this code for an “On Key Down” handler (not press - those don’t get non-character keys):
var myAudio = document.getElementById("cChord");
event = event || window.event;
var key = event.keyCode || event.which;
if (key == 39) {
if (myAudio.paused) {
myAudio.play();
} else {
myAudio.pause();
}
}