Volume 6, Number 4, December, 1998 - Noise News International

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Spacer signal via a small dynamic bone vibrator mounted on the forehead of the test subject. The stimulus is now based on a bone conduction path. Conventional electrodynamic bone conducting transducers for otoacoustic emission applications are not capable of high frequency operation. The high Fig. 11. Equivalent volume determination with precision spacers (G. Wong & T frequency limit for bone con- Embleton, JASA 1979). ducting otoacoustic emission with conventional transducers is within the range between 6 kHz and 10kHz. A wide-band piezoelectric otoacoustic emission transducer l4 that is capable of high frequency operation to beyond 25 kHz has been developed, and is shown in Fig. 12. This transducer is usable to more than 50 kHz. Initial trials have shown that sensation can be detected by the human subject for frequencies beyond 35 kHz when the transducer is placed in contact with the mastoid. v Future Innovative Ideas I will mention only two of the many innovative concepts that are currently under development that may further influence our enjoyment of future urban living. ActiveWallpaper@ The idea of active wall paper is based on the application of sound sensing and sound correcting elements onto a thin layer of composite material that can be deployed as wall paper. When sound waves strike the surface of the wall paper, sensors such as piezo sheets, detect the magnitude and phase of the sound. With the aid of imbedded circuits, a counter acting motion is generated to neutralise the incoming sound. This operation achieves two objectives: there is little or no sound transmission through the wall, and there is no sound reflection from the wall. In other words, the properties of an anechoic room can be implemented. In other applications, such as concert halls, the electronic circuits can be tuned, under the control of the concert master, such that the absorption and reflection of a wall can be changed at will. With imagination, one can think of many applications in an urban society - reducing party noise from neighbors or tuning your listening room to simulate a concert hall of your choice. Body Heat Power Generators Devices such as hearing aids and miniature biomedical devices that operate on relatively low voltages can be powered by voltage sources generated by human body heat. The idea is based on multi-junction thermocouple technology. A conservative estimate Fig. 12. Wide-band otoacoustic emission transducer (G. Wong et al., Int. Congress on Noise Control Eng. 1996). is that with modern integrated circuit manufacturing technology, a small patch similar to the size of a first aid bandage may be sufficient to power a hearing aid or other device in the field of nano-technology. Summary and Conclusions Advances in electroacoustics pertaining to acoustical measurements and standards have been described. The material covered includes new acoustical standards, active noise control, microphone array for hearing aids, 3-D sound intensity measurement, miniature noise dose and sound level measuring instruments, noise isolation cap to detect the presence of electromagnetic field, microphones with improved phase match, and several acoustical measuring techniques. Some of the methods, such as the precision determination of equivalent volumes for microphones calibration have already become one of the many laboratory practices. Others, such as the interchange of microphones for acoustical calibrations are under consideration for incorporation in a proposed IEC standards for comparison calibrations of microphones. 15 We should applaud the many important advances that have been made by the acoustical community in 214 NoiselNews International 1998 December
the last twenty years and be ready to welcome the ones that will surely follow in the next decade. References 1. S.J. Elliott and P.A. Nelson, Active noise control, Noise/News International, 2, 75-98, 1994, Jiri Tichy, Applications for active control of sound and vibration, NoiselNews International, 4, 73-86, 1996. 2. G.E. Warnaka, Active attentuation of noise - the state of the art, Noise Control Engineering Journal, 18, 100-110, 1982, L.J. Eriksson, Active sound and vibration control; A technology in transition, Noise Control Engineering Journal, 44,1-9,1996. 3. G. J. Pang et al., Performance of a digital ANR hearing protector in a reverberant chamber, 1. Acoust. Soc. Am. 100(4), Pt.2, 2675, 1996. 4. YamahaBand & OrchestralAccessory.YamahaCorp., Band & Orchestral Division, Box 899, Grand Rapids MI 49512-0899. 5. WilliSoede et al., Assessment of a directional microphone array for hearing impaired listeners, J. Acoust. Soc. Am. 94(2), Pt. 1,799808, 1993. 6. H. Suzukiet al., Performanceevaluationof a three dimensional intensity probe, 1. Acoust. Soc. Japan (E) 16,4,233-238, 1995. 7. G.S.K. Wong, Precision A.C. voltage-levelmeasuring system for acoustics, J. Acoust. Soc. Am. 65(3), 830-837,1979. 8. G.S.K. Wong,Development of a miniature sound-levelmeter, J. Phys. E. Sci. Instrum. 10, 301-305, 1977. 9. E. Frederiksen,Phase characteristicsof microphones forintensity probes, Proc. of 2nd Int. Congress on Acoustic Intensity, Senlis, 23-30, 1985. 10. G.S.K. Wong and T.F.W. Embleton, Three-port two-microphonecavityfor acousticalcalibrations,J.Acoust. Soc. Am. 71(5),1276-1277,1982. II. G.S.K. Wong, Precision method for phase match of microphones,J. Acoust. Soc. Am. 90(3), 1253-1255, 1991. 12.B. H. Meldrumand S.Thwaites,Primary microphonecalibration at CSIRO,Australia, Chapter 12, 199-212,in AlP Handbook of Condenser Microphones. Theory, Calibration, and Measurements, edited by George S. K. Wong and Tony F. W. Embleton (American Institute of Physics, New York, 1995). 13. G.S.K. Wong and T.F.w. Embleton, Arrangement for precision reciprocitycalibration of condenser microphones,J. Acoust. Soc. Am. 66(5), 1275-1280, 1979. 14.G. S. K.Wonget al., A wide-bandpiezoelectrictransducerfor otoacoustic emission applications, Proceedings International Congress on Noise Control Engineering, Liverpool, United Kingdom, Vol.5, 2565-2569,1996. 15. George S.K. Wong and Lixue Wu, Internchange microphone method for calibration by comparison, Proc. INTER-NOISE 98, Christchurch, New Zealand (to be published). ASA Publishes International Standards Catalog For the first time, the Standards Secretariat of the Acoustical Society of America is offering a complete set of international standards in Acoustics, Noise, Bioacoustics, and Mechanical Vibration and Shock produced by the following International Technical Committees and Subcommittees under the International Organization for Standardization (ISO), and the International Electrotechnical Commission (1EC). • ISO/TC 43 • ISO/TC 43/SCI • ISO/TCIOS • ISO/TC lOS/SCI .' ISO/TC IOS/SC2 .' ISO/TC IOS/SC3 " ISO/TC IOS/SC4 .' ISO/TC IOS/SC5 .' ISO/TC IOS/SC6 " IEC/TC 29 ACOUSTICS NOISE MECHANICAL VIBRATION AND SHOCK BALANCING, INCLUDING BALANCING MACHINES MEASUREMENT AND EVALUATION OF MECHANICAL VIBRATION AND SHOCK AS APPLIED TO MACHINES, VEHICLES, AND STRUCTURES USE AND CALIBRATION OF VIBRATION AND SHOCK MEASURING INSTRUMENTS HUMAN EXPOSURE TO MECHANICAL VIBRATION AND SHOCK CONDITION MONITORING AND DIAGNOSTICS OF MACHINES VIBRATION AND SHOCK GENERATING SYSTEMS ELECTROACOUSTICS The International Standards (as well as various Draft documents) of the above International Technical Committees and Subcommittees are being distributed by the Acoustical Society under license agreement from the American National Standards Institute (ANSI) within the United States. This International Standards Publication Program complements the National Standards Program, under which all of the acoustical standards produced by the four S Committees (for which ASA holds the Secretariats, under ANSI Procedures) are published, copyrighted, and distributed by P~SA. For either the National Standards Catalog, or the International Standards Catalog, or both, pllease contact A. Brenig, ASA Standards Manager, Acoustical Society of America, 120 Wall Street, 32nd Floor, New York, New York 10005-3993, USA. Telephone: + 12122480373; Fax: ~"1 212 248 0146; E-mail: asastds@aip.org 1998 December NoisefNews International 215
Page 1 and 2: Volume 6, Number 4 1998 December IN
Page 3 and 4: Editorial Stllff G. Maling, Jr., Ma
Page 5 and 6: Anechoic Chambers with EMW lining T
Page 7 and 8: "Finally, an Outdoor Sound Propagat
Page 9 and 10: YOUR NEXT SOUND METER • Workplace
Page 11 and 12: Feature Noise Control Standards for
Page 13 and 14: specify in more detail relevant mea
Page 15 and 16: c: o .~ "E f---7""'lf-1I:-i~;J4'.--
Page 17 and 18: References 1. Council Directive 89/
Page 19 and 20: Feature Advances in Acoustical Stan
Page 21 and 22: (a) M 4 6:~f=========::::CI~ Fig. 3
Page 23: Adaptor for Microphone & Preamplifi
Page 27 and 28: CONTROL The illustrations in thisfe
Page 29 and 30: Application to machines with connec
Page 31 and 32: Application with a thin screen. Exa
Page 33 and 34: Application with light single walls
Page 35 and 36: European News A. Cops, European Edi
Page 37 and 38: Pan-American News George Maling, Pa
Page 39 and 40: Contest entry forms and other mater
Page 41 and 42: Newly published ISO and IEC Standar
Page 43 and 44: ACOUSTICS ANSI Sl.15-1997-Part 1, M
Page 45 and 46: NNI Directory Organizational and Ed
Page 47 and 48: ~----- REAL TIME ANALYSER APPLICATI
Page 49 and 50: Brazil: +55 II 8200388; +55 II 8207
Page 51 and 52: The BS-112 comes equipped with a 6-
Page 53 and 54: 518584 3754; FAX: +1 5185809525; e-
Page 55 and 56: World Conference Calendar This cale
Page 57 and 58: COLIN GORDON & ASSOCIATES Specializ
Page 59 and 60: The NewMo e 2 Real Tune Analyzer Fe

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