Key technical issues for harmonization of methods for prominent discrete tone analysis

摘要

Presence of tonal components in noise spectrum is one of serious problems of product noise,not only limited to IT equipment, but also to the others. To quantify the subjective influence atthe ear position of the equipment users, the noise test codes dedicated for IT equipment (ISO7779, ECMA-74, ANSI S12.10-1 etc.) define two alternative and/or parallel metrics: tone-tonoiseratio and prominence ratio.This paper comprehensively lists and discusses key technical issues related to these twometrics. For the purpose of identifying the key issues, the historical methods during the lasttwenty years ago or more were reviewed, including changes (transition) of definitions ofcritical band, threshold of hearing, frequency resolution of spectral analysis, background noiserequirements and the corresponding correction, microphone positions for subassemblymeasurement, frequency range of interest, considerations for non-steady noise, and so on.In addition, to some of most important issues, practical resolutions (RECCOMENDATION) bythe author are also proposed.