Yea I was just thinking about getting just a straight mute, that will do the trick for now.
A Straight mute want make you sound any softer. At lest it shouldn't. If it does then you not using the right amout of air to play the with the mute or your trumpet.
As for pratice mutes. You have two chooses. For about $150 you came buy a stilent brass mute. These mutes are cool because they have a micorphone built into the mute. you get a box that you can pluge headphones in and listen to yourself. But there are some down sides. The sound quality not ever good. It kind of goes back to the idea of not facing your bell at the person your performing to. The mute itself also adds all of resistances to the horn. People who tend to plaay with the mute alot tend to have a raspy tone.
The second choose is probability the best. Its a pratice mute put out by Denis Wick. It looks kind of like a one of those cheap card board mutes. The mute make you as soft as the silent brass, but without the added resistance. This mute runs somewhere between $50 and $60. Much cheaper that the silent brass and in I think much better.