Annoyance of Tonal Noise: A Parametric Study

The four physical characteristics of environmental noise upon which depends its numerical rating are level, duration, intermittency (or variability) and quality.Quality is determined primarily by frequency spectrum, but also by impulsive nature and tonal character when present.This paper concerns only the last-mentioned.Although, physically, tonal character belongs to the spectrum domain, it confers on environmental noise an annoying quality for which some adjustment of its rating is needed in comparison to a broadband noise of similar level.The origin of a "tone correction" can be traced to Rosenblith el al. (1953) in a prediction scheme for community reaction.It took a form equivalent to adding 5 dB to the measured level, and has persisted in this form to the present day.The first edition of BS 4142 appeared in 1967 and speci ed acorrection of 5 dBtA) when there was a "distinguishable discrete continuous note .Since then there have been numerous criticisms of this all-or-none rule.Replies to a questionnaire issued to users by the British Standards Institution in 1970 already indicated that the correction was felt in many cases to be too small to account for public complaints.However, no change was made since to substitute a larger value would have placed too great a premium on deciding subjectively what is "distinguishable" and "discrete".Fisher (1982) 'found that 60% of local authorities encountered difficulty with the Standard in a later survey of 63 local authorities, reported by Williams and Robinson (1988), 40% of those with experience of