Sound Traps
Sound traps are the sound buffers in the mastering studio and are very important to the listening process before anything is even done to master a song.
Usage of sound traps vary from studio to studio. You can usually find them in plain sight in corners, walls, on the ceilings and possibly suspended. Front, rear, side locations are also used so you have a well prepared room that will keep the unwanted sounds tamed from going all over the place.
Sound traps can be made of foam, cushion with special patterns such as curved loops or sharp angles depending on their purpose in the studio. Bass traps tend to be the most widely used in the mastering studio because the bass frequencies are the hardest to control. A lot more effort needs to be made when dealing with low frequencies. On that note you know that the mids & high frequencies are easier to control.
When listening to your favorite song on a regular radio in a untreated empty room, you are going to hear that music an all the reflections that go with that room. Putting on headphones in this situation is almost the night & day difference of what was discussed here. Of course the sound you get from headphones close to your ear is totally different from speaker listening.
So we must give thanks to the makers of those beautiful sound traps. They are like the icing on the cake to the perfect audio mastering studio next to all of the other important components.