I just realized posting this question in another thread it will probably get passed over by the original poster's question. I have recently purchased a cornet and trying to teach myself while waiting to find a trumpet teacher. I was wondering if a practice mute for a trumpet will work in a cornet and what a good practice mute would be. The only reason I am asking about a mute is the fact that I live in an apartment complex and don't want to disturb the neighbors too much.

For apartment dwellers a practice mute is a good idea. Using a practice mute you can hear yourself well enough to get a feel for what you're doing. By my experience with practice mutes, they create some back pressure which makes it a little more difficult to blow than without one. But that also is beneficial to building endurance and power. The only true practice mute I ever used was a "Humes & Berg" brand "whisper mute". I used it many years ago during a period that I spent a lot of time in hotels. Another good way to practice quietly is to use a "Silent Brass" system marketed by Yamaha. It employs a device that inserts like a mute, but you wear earphones, and it has a tape player capability that allows you to use accompaniment or play-along cassettes for practice. The whisper mute runs around $40, the Silent Brass system is over $100.