I know how much I want to eat when I go out for a meal and am very unlikely to decide to eat more wheni get there, muzak or no muzak.
I have one or two courses and know in advance how much I want. If having two courses, I have a starter and main course. I do not eat steak, so I am not buying the most expensive dishes, muzak will not persuade me to order a steak, I do not like it. Ditto with desserts, I do not really like them. Very occasionally I will be tempted by a plain creme brulee, may be once or twice a year. Nothing to do with muzak. Same with drink. i drink per meal - and a jug of tapwater- and usually a coffee.
Muzak, irritating and a waste of time as it doen't affect my buying decisison. Those are made before I even get to the restaurant.