Predicting Speech Interference and Annoyance from A-Weighted Sound Levels

Abstract

A sample of 741 noises measured in factories and in construction equipment was used to relate speech interference levels to A-weighted sound levels. A mathematical formula was developed which predicts the speech interference level from the A-weighted sound level with little error. A graph was drawn for use in predicting speech interference effects directly from A-weighted sound levels. Another sample of 235 noises measured along industrial plant boundaries was used to relate A-weighted sound levels to the level rank used for rating annoyance. A method was developed for predicting the level rank from the A-weighted sound level with satisfactory accuracy. A graph was drawn for predicting the degree of annoyance directly from the A-weighted sound level. The methods developed for predicting speech interference and annoyance effects directly from A-weighted sound levels are believed to be as accurate as the methods utilizing octave-band sound-pressure levels on which they are based.