The Effects of Irregularity and Intermittency on the Judged Annoyance of Impulsive Noise

l lNTRODUCI'lONIt is now generally accepted that, when impulsive noise is measured using the equivalent continuous A-weighted sound pressure level (LAN).there is a need for a penalty to be applied to the measured level to take account of the enhanced annoyance of such a noise relative to more continuous noise.However.little work has been carried out to investigate various aspects of the noise signal in relation to the degree of annoyance.A series of subjective experiments was conducted at the National Physical Laboratory as part of an evaluation of impulsive noise under contract to the Department oi One of the effects to be investigated in that series of experiments This then led to a later Environment (1).was the effect of irregularity on the annoyance rating.experiment to investigate the effect of intermittency on annoyance ratings.This paper describes these two experiments investigating the effects of irregularity and intermittency on the judged annoyance of impulsive noise and assesses the signi cance of the data obtained from both experiments. SUBJECTIVE EXPERIMENTS Test Facilities11.1 Listening RoomThe room was carpeted and furnished to give a reasonable simulation of domestic living room conditions and the background noise was steady at 25 dB(A). Signal simulation and reproductionThe experiments made use of both simulated impulsive noises and recordings of real noises.The simulations were obtained using digital synthesis software running on a