An ‘easy to use’ Wide-Span Integrating Meter

摘要

Ever since sound level meters were first produced, their small dynamic span has been a constant problem. For example, the minimum mandated span in the IEC standard 61672-1:2002(Electroacoustics – Sound level meters) is only 60dB and while this is only 1000:1 in pressure terms, itequates to an exposure ratio of 106:1. However wide such a span may seem to an electronic engineer,to an acoustician an instrument with such a span needs constant range changing to ensure the soundlevel remains in the instrument’s linear range. The range change error problem was partiallyovercome by the introduction of the Wallis/Holding technique, where two stacked integration chainswere constantly compared with the one in its linear range used. This technique has been refined; usingnew technology available, in order to meet the new IEC standard 61672-1:2002 and produce an ‘easyto use’ handheld instrument.