People can "hear" inanimate objects

Since blind individuals may be particularly tuned in to such sounds, the research helps explain how they can often find doorways, windows and objects without seeing or touching them. It may also lead to a better understanding of echolocation, the technique used by certain animals, like bats and dolphins, to detect reflected sound.

The study also suggests that true silence, except in artificially created environments like soundproof booths, does not exist.

"In the real world there is always some type of ambient noise," said Lawrence Rosenblum, who conducted the study with co-authors Ryan Robart and Ethan Chamberlain

For the study, Rosenblum and his colleagues used a rolling equipmentcart to move blindfolded students around a basic campus classroomconsisting of a linoleum floor, sheet rock walls, a tile ceiling, twowhite boards and three large windows covered with plastic blinds.

For the first experiment, students were allowed to speak and thenuse the sound of their own voices to determine what part of the roomthey were in. They were nearly always accurate. In follow-upexperiments, the students had to be quiet, but either relied uponsounds made by a clicker, recorded sound bursts or no extra sound atall.

The students again aced the tests, although they were not as accurate during the quietest experiment.