ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

3aEA6. Considerations of errors in computer-based measurements.

Alan D. Wallis

Cirrus Research plc, Acoustic House, Hunmanby YO14 0PH, UK

The use of computers has come to dominate acoustical measurements as was predicted at ICA 1983 in Paris. However, what was not predicted was that a generation of acousticians would arrive with no previous experience of older analogue systems. To some of these new generation workers, ``the computer is always right'' and little or no thought is given to the limitations and accuracy restrictions of a totally digital system. Automatic checks routinely done before and after measurements on previous generations of instruments are sometimes ignored, while instrument tolerances are assumed to be zero and calibrations are assumed to be perfect even though logic suggests otherwise. Consideration is given to making basic checks on computer based instruments, so that reasonable reliance can be placed on the results, often using old and traditional methods brought up to data and translated from the analogue to the digital world. Sample case histories of particular ``real world'' errors are given, with some idea of the practical limitations of new technology instrumentation and where they sometimes fall short of older units. These are compared with some requirements of ANSI and international standards.