Status of standards on digital systems for sound and vibration analysis

Abstract

Existing ANSI (American National Standards Institute) standards deal primarily with analog acoustical instruments and their use—following traditional thinking and procedures of acousticians. They are relevant to the analog parts of a digital signal processing system such as the signal itself (time and frequency characteristics), transduction (directionality, linearity, frequency response of microphones or vibration pick-ups), and output (preferred frequencies, reference quantifies). They are also relevant to digital components that mimic closely the behavior of analog devices, e.g., filters that receive signals continuously. The next revision of S1.11 will explicitly include specifications for the performance of both analog and digital filters. The IEC (International Electrotechnical Commission) acoustical standards similarly relate to analog instruments and their use. The next several years should see progress in the development of standards for digital acoustical instrumentation, but before this can happen acousticians must recognize and widely discuss the technical problems that exist. General consensus should be reached on many factors, one of the most fundamental is the possible methods of achieving a desired degree of accuracy for a given kind of acoustical signal. Standards written prematurely risk biasing measurement procedures, and instrumentation to meet these needs, in what may be less-than-optimum directions.