“Some people bring their kids to the London ones, with sound-proof headphones,” she said.
The apparatus was driven by a motor and reducing gear, which were isolated in a sound-proof box.
The rapping sounded muffled and dim in that sound-proof place.
He couldn't have heard much—the walls are sound-proof and the door fairly tight.
Pity there isn't a sound-proof room for practising in this school.
If left alone in the room with the baby, throw a sound-proof rug over it and escape.
In a moment I was within and had swung shut and sealed the sound-proof door.
Now again the heavy, sound-proof door of the study began to open—noiselessly, inch by inch.
There were no windows, and it appeared to be a kind of sound-proof call-box, which indeed it was.
Donald was studying the painting, when the lanky clerk issued from the sound-proof inner chamber.