I admit my immediate reaction to the rooster collar was negative, so I thought I'd make a different suggestion for people to consider and try. I have *not* done this myself, as we're rooster-legal, but I know someone who did, but she's a bit flaky.
At "bedtime" put the rooster in a low box - supposedly roosters need to stretch their necks up to crow and if they can't do so, they won't. If the box is in a closed, dark area, even better, because roosters will crow at the moon and car headlights - they are bird-brains after all. Many neighbors will tolerate crowing during the day - maybe leave him boxed a little longer on Sunday mornings if you've got neighbors who like to sleep in, so I would see if they will accept day-time crowing if you promise night-time silence. A rooster can easily go the night without
feed, but if it's hot, I suggest a small hanging waterer
should go in.
This could at least be a help if you've got young roosters you're trying to grow to pot-sized. I'm pretty tolerant, but the summer my neighbor had 11 of them, even I spoke up and suggested he needed to reduce the noise level! If I'd known about the box trick then, I'd have had him try it as I know he was just trying to get them a bit bigger and didn't plan to keep all of them.