Sound reverberation time measuring equipment - has loud-speaker sound meter and time counter responsive to start and stop signals

摘要

Acoustical equipment is used to measure the reverberation time of a room and comrpises a loud-speaker (1), an off switch (2), a sound meter (3), and a time counter (4). The time counter (4) measure the time interval between the switch-off of a sound generated by the loud speaker and the time at which the residual sound has decreased by 20 decibels. For a sound generated by the loud-speaker (1), a first signal corresponding to the sound is produced by the sound meter (3). The meter circuit (5) produces a signal which corresponds to a level 20 decibels down from the first signal. This second signal is set to stop the counter (4). When the sound generated by the loud-speaker (1) is stopped, the counter is started and it stops when the signal level is equal to the setting of the second signal.