A special form of noise reduction

Popmusic reproduction or reinforcement in disco's or poppodia on a very high sound pressure level is highly appreciated by the so called target group. For the neighbours, this can be very annoying, especially when these music sessions take place during the night. A poor sound insulation creates an inadmissable sound immission level in e.g. bedrooms. Noise reduction methods of a constructional nature are in most cases very expensive. Two methods of active noise reduction are tried out in the sound system of a music school in The Netherlands and other premises: one by 'anti-sound' and the other is based on the phenomenon of the missing fundamental. One of the experiments with the results are discussed in the paper below. The latter is called 'dormant Bass' (dB).