Sound-proof

Have you been living under a rock with sound-proof walls?

Source: tatoeba (4867400)

In an interview six years ago, Henry Loomis remembered an experiment he took part in when he was about seventeen years old. Henry slept in a sound-proof room with electrode devices attached to his head. Alfred Loomis was nearby with a microphone device. He told his son in a soft voice that Henry's favorite object, his boat, was on fire. Henry Loomis jumped out of bed to save the boat. This experiment and others helped Alfred Loomis show how emotional upset could change human brain waves.

Source: tatoeba (12229807)