With the present coronavirus situation, many horn players are suddenly finding they need to practice in less than optimal spaces, as in spaces where other people will be perhaps very bothered by the noise.
This is something every horn player has navigated over many years. As a student I was lucky, I practiced (a lot!) at my parents’ house, and then in practice rooms at schools. After that, I entered the real world.
In my first apartment, I practiced often with a mute and a pillow; I did not own a proper practice mute. The other tactic I took was one I heard attributed to the great Barry Tuckwell. Supposedly, when touring, he would practice with the TV on loud on cartoons. This actually works; all the noise from the cartoon helps mask the horn practice sounds.
As a young professional hornist in Nashville, my first season there I did virtually all of my practice in a walk in closet. VERY dead space, but cuts the sound down to your neighbors greatly.
Then, when our kids were little, quite regularly my evening practice was with this Yamaha silent brass. I got it used and inexpensively, the previous owner was older and felt it caused too much back pressure. I find that aspect OK, the only big issue is that over time you may find it hard to find your normal pitch center. When using it I liked to aim for shorter sessions of relatively intense practice of technical things, rather than tonal studies.
A final suggestion I heard from a student today, that works surprisingly well in a pinch, is practice without your bell on if it is a screw bell horn. Put your hand in as normal, to keep the pitch centered – and it will be quieter.
There is also the question of what and how to practice with a disrupted practice (and life!) schedule. I’ll have more on that soon (more here!), I have my own experiences to share that are more extensive than the average pro.