fixed it, the 'muted' attribute is actually a property:
$("#dinner").click(function() {
var bool = $("#player").prop("muted");
$("#player").prop("muted",!bool);
});
This can also be done slightly more succinctly by using ES6 arrow functions and also by providing a function to prop()
which accepts the current state of the property as an argument. In this case the code would look something like this:
$('#dinner').on('click', () => $('#player').prop('muted', (_, muted) => !muted));