A comparison of noise measures for assessing vehicle noisiness

Abstract

The control of vehicle noise is currently achieved by using the A-weighted sound pressure level and measuring the maximum sound level achieved during a full acceleration test. Doubts have been expressed about the continuing use of the scale of dB(A) as the sole means of assessing and regulating this noise, since it is felt that some vehicles emitting the same sound level when measured on the dB(A) scale can differ appreciably in terms of their subjective noisiness. This paper describes four experiments where the aim was to determine whether other noise scales would be more appropriate for measuring vehicle noise. A total of over 100 subjects made assessments of the noisiness of a wide range of recorded vehicle noises. The sounds were replayed in two listening rooms designed to simulate indoor and outdoor listening conditions. It was concluded that, generally, loudness measures were most closely related to average noisiness ratings, but provided that the frequency spectra of vehicle sounds are not greatly different, loudness measures have no advantage over the A-weighted level currently employed.