THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

References 209acoustical output and feeds it to a spectrum analyzer, which then relays the datato a display or a recorder. The dedicated functions of the traditional hardware—signal generation, filtering, analysis, and data handling—can now be performedby software in such a manner that the personal computer essentially constitutesthe test platform. The user interface can even be made to emulate familiar analoginstrumentation controls using standardized Windows TM controls.Measurement procedures with a PC require a high-quality D/A (digital to analog)converter for transforming the digital representation of a sine sweep created by theprogram into analog signal, and an equally good A/D converter for transformingthe measured analog signals back into the digital domain for analytical purposes.Most sound cards provide at least 16-bit resolution, and some sound cards can evenmeasure frequency response from DC to 20 kHz with an accuracy of ±0.25 dBand distortion as low as 0.003%.The SoundCheck TM PC-based electroacoustical measurement system, essentiallya software package, requires only a computer, sound card, amplifier, microphone,and microphone power supply. The SoundWare TM software featuresa family of “virtual instruments” that perform the functions of a signal generator,voltmeter, oscilloscope, spectrum analyzer, and real-time analyzer. The PC isrendered capable of measuring frequency, time, phase response, total harmonicdistortion (THD), impedance, as well as performing other electrical tests. Sucha system can be applied to evaluating loudspeakers, microphones, telephones,hearing aids, headsets, and other communication devices. Programming of testsequences allows the PC to be used not only for research and development work,but also in high-speed production testing and inspection procedures.ReferencesAmerican National Standard Institute. 1966. ANSI Standard Specification for Octave, Halfoctaveand Third-Octave Band Filter Sets, S1.11-1966.American National Standard Institute. 1978. ANSI Standard Specification for PersonalNoise Dosimeters, ANSI S1.25-1978.British Standards Institution. 1983. Personal Sound Exposure Meters, BS6402.Cooley, J. W. and Tukey, J. W. 1965. An algorithm for the machine calculation of complexFourier series. Mathematics of Computation 19:297–301.Crocker, Malcolm J. (ed.). 1997. Encyclopedia of Acoustics, Vol. 4. New York: John Wiley& Sons: Part XVII, pp. 1837–1879, and Part XVIII: 1933–1944.Fraden, Jacob. 1993. AIP Handbook of Modern Sensors: Physics, Design and Applications.New York: American Institute of Physics, Chapters 3, 4, 9, and 11. (While thisuseful handbook covers devices for sensing temperature, light, humidity, and chemicalprocesses, the chapters cited here refer to topics applicable to acoustic measurements.)Harris, Cyril M. (ed.). 1991. Handbook of Acoustical Measurements and Noise Control,3rd ed., New York: McGraw-Hill, Chapters 5, 8, 9, 11–15.Hixson, Elmer L. and Busch-Vishniac, Ilene. 1997. In: Crocker, Malcolm J., ed. Transducerprinciples. Encyclopedia of Acoustics, Vol. 4. New York: John Wiley & Sons, Part VVIII,Chapter 59.