Abstract:

With the general consensus of practicing noise control consultants that the two different sets of criterion curves for evaluating room noise contained in ANSI S12.2-1995 [room criterion (RC) and balanced noise criterion (NCB)] should be replaced with a single set of criterion curves, the authors believe that lessons can be learned from the computer industry, especially in accounting for noises with abnormal characteristics. This industry realizes that the noise emissions from their products should be compatible with the acoustical requirements of the environment in which the products are installed. The types of computer products cover a wide range with respect to functionality, size, sound power level, and spectral and temporal characteristics of their emissions. The rooms in which these products are installed also cover a wide range, including many types with significantly different levels of acceptable noise. In addition to using A-weighted descriptors (sound power level to describe product emissions and sound-pressure level to describe room noise levels), the computer industry has recognized the need to take into account and to characterize abnormal features of the noises, such as prominent discrete tones (ECMA-74-1996 or ANSI S1.13), tonal modulation or beating, and impulsive or fluctuating sounds. This paper presents some of these experiences from the computer industry in the context of establishing room noise criterion curves. [See NOISE-CON Proceedings for full paper.]