Preferred listening level for speech disturbed by fluctuating noise

This paper is a sequel to an earlier one in which we investigated, among other things, the influence of stationary background noise on preferred listening level. The influence of fluctuations in noise level on preferred listening level was compared with the influence of stationary noise. It turned out that the preferred listening level for a read-aloud text, adjusted by listeners against a background of noise, is hardly influenced by fluctuations in the noise, provided the equivalent noise level (L_eq) in dB(A) remains the same. This holds both for systematically modulated noise down to 0·1 Hz and more randomly fluctuating noise such as traffic noise. Average preferred listening level proved to be an accurate measure for evaluating various conditions, such as modulation frequency and noise level, in a single experiment.