For a Yamaha trumpet with a 0.460-inch bore size, you will need a small trumpet mute. For a Yamaha trumpet with a 0.468-inch bore size, you will need a medium trumpet mute. For a Yamaha trumpet with a 0.472-inch bore size, you will need a large trumpet mute.
If you are not sure what size trumpet you have, you can measure the diameter of the bell. The bell diameter of a Yamaha trumpet is typically between 4.5 inches and 5 inches. A small trumpet mute will fit a bell diameter of up to 4.75 inches. A medium trumpet mute will fit a bell diameter of between 4.75 inches and 5 inches. A large trumpet mute will fit a bell diameter of over 5 inches.
In addition to the size of the trumpet mute, you should also consider the material the mute is made of. Trumpet mutes are typically made of brass, copper, or aluminum. Brass mutes are the most common type of mute and they produce a warm, mellow sound. Copper mutes produce a brighter, more focused sound. Aluminum mutes produce a dry, articulate sound.
The best way to choose a trumpet mute is to try out different mutes and see which one you like the best. You can try out different mutes at a local music store or you can order them online.