A list of sites (including html) for the Acoustics FAQ is at http://super.zippo.com/~consult/Acoustics_FAQ_mirrors.html
The Active Noise Control FAQ by Chris Ruckman is also at http://www.xis.com/~ruckman/
The Tinnitus FAQ deals with a range of hearing disorders. It is maintained by Mark Bixby and available at http://www.cccd.edu/faq/tinnitus.html
The Audio FAQ, with everything you ever wanted to know about the subject, from preamplifiers to speakers and listening room acoustics. It is located in the pub/usenet/rec.audio.* directories
The comp.speech faq maintained by Andrew Hunt has information on speech processing and some software links
Spectrogram 3.2 - an excellent Win95 spectrum analysis program (freeware) by Richard Horne is at: http://tinker.winsite.com/info/pc/win95/sounds/gram32.zip
The comp.speech faq has several links to speech related software including speech recognition and text to speech programs.
There are a few programs for various platforms listed at URL http://www.cisab.indiana.edu/CSASAB/index.html The programs listed are mainly for sound analysis and editing.
Some software is available for audio systems design at URL ftp://ftp.uu.net/usenet/rec.audio.high-end/Software
Odeon is a program for architectural acoustics. A demonstration version is available by ftp. The demo includes a large database for coefficients of absorption. A web page at URL http://www.dat.dtu.dk/~odeon/index.html describes the capabilities of the program and gives the ftp address.
Also some interactive acoustics software (eg room acoustics, RT, decibel conversion etc) is available at a few web sites.
10^(-5) indicates 10 raised to the power of minus 5 1.0E-12 indicates 1.0 x 10^(-12) 1 pW indicates 1 picowatt i.e. 1.0E-12 Watt W/m^2 indicates Watts per square metre lg indicates logarithm to base 10 sqrt indicates the square root of pi = 3.142
How small and rapid are the changes of air pressure which cause sound? When the rapid variations in pressure occur between about 20 and 20,000 times per second (ie at a frequency between 20Hz and 20kHz) sound is potentially audible even though the pressure variation can sometimes be as low as only a few millionths of a Pascal. Movements of the ear drum as small as the diameter of a hydrogen atom can be audible! Louder sounds are caused by greater variation in pressure - 1 Pascal, for example, will sound quite loud, provided that most of the acoustic energy is in the mid-frequencies (1kHz - 4kHz) where the ear is most sensitive.
In acoustics the decibel is most often used to compare sound pressure, in air, with a reference pressure. References for sound intensity, sound power and sound pressure in water are amongst others which are also commonly in use.
Reference sound pressure (in air) = 0.00002 = 2E-5 Pa (rms) " " intensity = 0.000000000001 = 1E-12 W/m^2 " " power = 0.000000000001 = 1E-12 W " " pressure (water) = 0.000001 = 1E-6 PaAcousticians use the dB scale for the following reasons:
Sound Pressure Level = 20 x lg (p/0.00002) dBPeak levels are occasionally quoted. During any given time interval peak levels will be numerically greater, and often much greater than the (rms) sound pressure level.
The first tentative standard for sound level meters (Z24.3) was published by the American Standards Association in 1936, sponsored by the Acoustical Society of America. The tentative standard shows two frequency weighting curves "A" and "B" which were modelled on the ear's response to low and high levels of sound respectively.
The most common weighting today is "A-weighting" dB(A), which is very similar to that originally defined as Curve "A" in the 1936 standard. "C-weighting" dB(C), which is used occasionally, has a relatively flat response. "U-weighting" is a recent weighting which is used for measuring audible sound in the presence of ultrasound, and can be combined with A-weighting to give AU-weighting. The A-weighting formula is given in section 8 of the FAQ.
In addition to frequency weighting, sound pressure can be weighted in time with fast, slow or impulse response. Measurements of sound pressure level with A-weighting and fast response are also known as the "sound level".
Some sound level meters can measure the average sound level of a noise over a given time. It is called the equivalent continuous sound level (L sub eq) and is A-weighted but not time weighted.
Combined sound level = 10 x lg ( 10^(62/10) + 10^(73/10) ) = 73.3 dBNote: for two different sounds, the combined level cannot be more than 3 dB above the higher of the two sound levels. However, if the sounds are phase related there can be up to a 6dB increase in SPL.
The basilar membrane is wider at its apex than at its base, near the oval window, whereas the cochlea tapers towards its apex. Different groups of the delicate hair sensors on the membrane, which varies in stiffness along its length, respond to different frequencies transmitted down the coil. The hair sensors are one of the few cell types in the body which do not regenerate. They may therefore become irreparably damaged by large noise doses. Refer to the Tinnitus FAQ for more information on hearing disorders.
There are other health hazards from extended exposure to vibration. An example is "white finger", which is found amongst workers who use hand- held machinery such as chain saws.
Sound Intensity Level = 10 x lg (I/1.0E-12) dBNote: 1.0E-12 W/m^2 normally corresponds to a sound pressure of about 2.0E-5 Pascals which is used as the datum acoustic pressure in air.
Sound intensity meters are becoming increasingly popular for determining the quantity and location of sound energy emission, in situations where a sound level meter would not be suitable.
If the noise source is outdoors and its dimensions are small compared with the distance to the monitoring position (ideally a point source), then as the sound energy is radiated it will spread over an area which is proportional to the square of the distance. This is an `inverse square law' where the sound level will decline by 6dB for each doubling of distance.
Line noise sources such as a long line of moving traffic will radiate noise in cylindrical pattern, so that the area covered by the sound energy spread is directly proportional to the distance and the sound will decline by 3dB per doubling of distance.
Close to a source (the near field) the change in SPL will not follow the above laws because the spread of energy is less, and smaller changes of sound level with distance should be expected.
In addition it is always necessary to take into account attenuation due to the absorption of sound by the air, which may be substantial at higher frequencies. For ultrasound, air absorption may well be the dominant factor in the reduction.
For example, a lawn mower with sound power level 88dB(A) will produce a sound level of about 60dB(A) at a distance of 10 metres. If the sound power level was 78dB(A) then the lawn mower sound level would be only 50dB(A) at the same distance.
A good approximation for the speed of sound in other gases at standard temperature and pressure can be obtained from
c = sqrt (gamma x P / rho)where gamma is the ratio of specific heats, P is 1.013E5 Pa and rho is the density.
The speed of sound in water is approximately 1500 m/s. It is possible to measure changes in ocean temperature by observing the resultant change in speed of sound over long distances. The speed of sound in an ocean is approximately:
c = 1449.2 + 4.6T - 0.055T^2 + 0.00029T^3 + (1.34-0.01T)(S-35) + 0.016zT temp in degrees Celsius, S salinity in parts per thousand z is depth in meters
See also CRC Handbook of Chemistry & Physics for some other substances and Dushaw & Worcester JASA (1993) 93, pp255-275 for sea water.
A 10dB sound level increase is considered to be about twice as loud in many cases. The sone is a unit of comparative loudness with 0.5 sone=30 phons, 1 sone=40 phons, 2 sones=50 phons, 4 sones = 60 phons etc. The sone is inappropriate at very low and high sound levels where subjective perception does not follow the 10dB rule.
Loudness level calculations take account of "masking" - the process by which the audibility of one sound is reduced due to the presence of another at a close frequency. The redundancy principles of masking are applied in digital audio broadcasting (DAB), leading to a considerable saving in bandwidth with no perceptible loss in quality.
It is sometimes more useful to know the velocity or displacement rather than the acceleration. In the case of velocity, it is necessary to integrate the acceleration signal. A second integration will provide a displacement output. If the vibration is sinusoidal at a known frequency, f, then an integration is easily calculated by dividing the original by 2 x pi x f (noting that there is a phase change)
Example: A machine is vibrating sinusoidally at 79.6 Hz with an rms acceleration of 10 m/s^2. Its rms velocity is therefore 10/(2 x pi x 79.6) = 20 mm/s Its rms displacement is 10/(4 x pi^2 x 79.6^2) = 0.04 mm
If the vibration is produced by a motor inside a machine, it is usually desirable to ensure that the frequency of motor oscillations (the forcing frequency) is well above the frequency of the natural resonance of the machine on its support. This is achieved by altering the mass or stiffness of the system as appropriate.
The method of vibration isolation is very easy to demonstrate with a weight held from a rubber band. As the band is moved up and down very slowly the suspended weight will move by the same amount. At resonance the weight will move much more, but as the frequency is increased still further the weight will become almost stationary. In practical circumstances springs are more likely to be used in compression than tension, but the principles are exactly the same.
A further method of vibration control is to attempt to cancel the forces involved using a Dynamic Vibration Absorber. Here an additional "tuned" mass-spring combination is added so that it exerts a force equal and opposite to the unwanted vibration. They are only appropriate when the vibration is of a fixed frequency.
Active vibration control, using techniques akin to active noise control, is now coming into use.
Important:- Intuitive attempts to reduce vibration from machinery can sometimes instead aggravate the problem. This is especially true when care was originally taken to minimize vibration at the time of design, manufacture and installation.
In metric units 0.161 x room Volume T = ---------------------------------------------- sum of Surface areas x absorption coefficients
For the purposes of architectural design, the Sabine coefficient (calculated from reverberation chamber measurements) is preferred. Interestingly some absorbent materials are found to have a Sabine coefficient in excess of unity at higher frequencies. This is due to edge effects and when this occurs the value can be taken as 1.0.
The Odeon computer program includes a file of absorption coefficients.
Sound insulation is required in order to eliminate the sound path from a source to a receiver such as between apartments in a building, or to reduce unwanted external noise inside a concert hall. Heavy materials like concrete tend to be the best materials for sound insulation - doubling the mass per unit area of a wall will improve its insulation by about 6dB. It is possible to achieve good insulation with much less mass by instead using a double leaf partition (two separated independent walls).
Sound absorption occurs when some or all of the incident sound energy is either converted into heat or passes through the absorber. For this reason good sound absorbers do not of themselves make good sound insulators. Although insulation and absorption are different concepts, there are many instances where the use of sound absorbers will improve insulation. However absorption should not be the primary means of achieving good sound insulation.
It is very useful to have a single number to characterize the insulation of a partition. Measurements are often conducted in third- octaves, and the reduction plotted on a graph. A reference curve is then fitted to the measurements using a specified procedure, and the value of this curve at 500 Hz is taken as the figure. There is a slight difference in procedure between the U.S. and ISO standards, but the methods are basically similar. The same is also true for impact noise transmission assessment, where a standard tapping machine is in use to hammer floors. Sound pressure levels in the room below are monitored.
When the noise is from an external source such as a main road it may be possible, if planning authorities permit, to screen with a noise barrier. These can be effective providing that the direct line of sight between traffic and house is concealed by the barrier.
The weak point for sound transmission to and from a building is most often via the windows. Double glazing will usually afford noticeably better protection than single glazing, but in areas of high external noise it might be preferable to have double windows with a large air gap and acoustic absorbent material in the reveals. A drawback of improving external insulation is that, for some people, the resultant lower background level can itself be disturbing; it can also make noise transmission through party walls more apparent. The fitting of new windows may reduce the level of air ventilation, and it will be vital to compensate for this, if necessary with a noise attenuating system.
You may also need to consider noise penetration through the roof, floors, ceilings and walls.
Noise through party walls can be reduced by the addition of a false wall. This is constructed from a layer of sound insulating material, commonly plasterboard, separated from the party wall by a large void containing acoustic quilting. The false wall must not be connected to the party wall because that would allow sound transmission paths. The quality of construction is an important consideration if optimal levels of attenuation are desired. It is advisable to contact an independent noise consultant before allowing any building works to commence.
This method of noise control is becoming increasingly popular for a variety of uses. It is sometimes considered a miracle "cure-all" for noise problems which, at the present time, is not the case. For example noise cancellation in 3D spaces, such as living areas, is very difficult to achieve. However it can be more successful locally, eg for a passenger sitting in an aircraft or car. There are many institutions and companies around the world working on the technology to increase the circumstances where ANC can be used effectively. The award winning Active Noise Control FAQ is maintained by Chris Ruckman and available at a number of sites worldwide including:
" .. When the speed of an aircraft is supersonic, the pressure waves cannot get away ahead of the aircraft as their natural speed is slower than that of the aircraft. Slower, in this context, means just over 1200 km/hr at sea level and about 10% less at normal cruising altitude. Because they cannot get away, the pressure disturbances coalesce and lag behind the aeroplane, which is in effect travelling at the apex of a conical shock wave. The main shock wave is generated by the extreme nose of the aeroplane, but ancillary shocks are generated by all the major fuselage discontinuities. .. "
Ken Plotkin (kplotkin@access2.digex.net) on 24th July 1995 wrote:
[snip] .. A body moving through the air pushes the air aside. Small disturbances move away at the speed of sound. Disturbances from a slowly moving body go out in circles, like ripples from a pebble in a pond. If the body moves faster, the circles are closer in the direction of travel. If the body is supersonic, then the circles overlap. The envelope of circles forms a cone. The angle of the cone is determined by its vertex moving in the body's travel direction at the body's speed, while the circles grow at the sound speed. [snip] The existence of the "Mach cone", "Mach waves" and the corresponding angle, was discovered by Ernst Mach in the nineteenth century. [snip]
Large parabolic reflectors can be used very effectively to send and receive sound over significant distances. Check out your local science museum or exploratorium - there may be a demonstration. It is also possible to refract sound and focus it using a lens. The lens is constructed from a large thin bubble, say 2 metres across, filled with carbon dioxide. The effect is not very pronounced.
Sound can be directed by making use of constructive and destructive interference. This idea is used in column speakers, and commercial systems for reducing noise levels outside the dance floor area of discos.
See Science 14 October 1994 page 233, Scientific American (International Edition) February 1995 Page 32 or Physics Today September 1994 Page 22, all quite readable articles.
See also the following URLs:
James Davison (TKGN58A@prodigy.com) on 28th June 1995 wrote:[snip] .. I have been sufficiently interested to reconstruct the apparatus for producing this effect -- using a pair of piezoelectric transducers, an old oscilloscope and a signal wave generator -- materials costing only a few hundred dollars.
I am proud to say that tonight I managed to reproduce this effect -- the tiny bubble has the appearance of a tiny blue star trapped in the middle of the flask. It is distinctly visible to the unadapted eye in a dark room, and it is a very startling thing to see. [snip]
f = { c sqrt (S/LV) } / 2pi
Example: A 75 cl (7.5E-4 m^3) wine bottle with neck diameter 19 mm, bottle neck length 8 cm, air temp = 20 degC calculated resonance = 109Hz (actual resonance was 105Hz)Helmholtz resonators are sometimes employed as a means of passive noise control in air conditioning ducts. They may also be hidden in the wall design of auditoria and offices in order to improve the acoustics.
Pitch is also a subjective frequency ordering of sounds. Perceived pitch is dependent on frequency, waveform and amplitude or changing amplitude. Numbers can be assigned to perceived pitch relative to a pure frontal tone of 1000Hz at 40dB (1000 mels) thereby establishing a pitch scale.
Further info and examples on pitch from URL: http://www.music.mcgill.ca/auditory/Auditory.html
The ratio of frequency intervals for Just Intonation is demonstrated below in the scale of C major, though the same ratios apply to all the major keys:
C (9:8) D (10:9) E (16:15) F (9:8) G (10:9) A (9:8) B (16:15) C <- OctaveThe interval between E & F and between B & C is a semitone, whilst the other intervals are tones. The interval between any two notes above can be found by multiplying the intervening ratios; thus if all the above ratios are multiplied together the resultant is 2 because an octave is twice the original frequency.
The notes of minor scales differ from their major counterparts; one important difference being the flattened third. E flat is a minor third above the note C.
The use of Just Temperament causes serious problems of intonation when music modulates between keys. Equal Temperament is nearly always used as a compromise to the problem of tuning (see question 6.6).
WARNING - Breathing helium can be very dangerous.
A cavity will have certain resonant frequencies. These frequencies depend on the shape and size of the cavity and on the velocity of sound within the cavity. Human vocal cords vibrate non-sinusoidally in the vocal tract, giving rise to a range of frequencies above the fundamental. The vocal tract mainly enhances lower frequency components imparting the recognizable voice spectrum.
The velocity of sound in helium is much greater than in air, so breathing helium will raise the vocal tract's resonant frequencies. Although the vocal cords' vibrational frequencies are little affected by helium, the effect of higher cavity resonances is to alter substantially the relative amplitudes of the voice spectrum components thus leading to apparent pitch change.
Structural acoustics problems of interest involving water include the vibration of submerged structures, acoustic radiation from mechanically-excited, submerged, elastic structures; acoustic scattering from submerged, elastic structures (e.g., sonar echoes); acoustic cavity analysis; and dynamics of fluid-filled elastic piping systems. These problems are of interest for both time-harmonic (sinusoidal) and general time-dependent (transient) excitations. Water hammer in pipes can be thought of as a transient structural acoustics problem.
Structural acoustics problems of interest involving air include determining and reducing noise levels in automobile and airplane cabins.
Reference (for simple geometry problems): Sound, Structures, and Their Interaction Second Edition, by M.C. Junger and D. Feit, MIT Press, Cambridge, Mass (1986).
Example 1: A sound source, S, emits 1000 waves per second (1 kHz) and is moving directly towards an observer, O, at a speed of 100 metres per second (equivalent to approx 225 miles per hour). After 1 second the wave front, which is travelling at the speed of sound, will have travelled 340 metres from the original source position. Also after that second the sound source will have moved 100 metres towards the observer. 0 m 340 m S | | | | | | | | | O <-------------- 1000 waves ------------------> 100 m 340 m S | | | | | | | | | O <------- 1000 waves ---------> Therefore the same number of waves will occupy a space of 340-100 = 240 metres and the wavelength will be 240/1000 = 0.24 metres. To the observer the frequency heard will be the speed of sound divided by its wavelength = 340/0.24 = 1416.7 Hz.
Example 2: An observer moving at 100 metres per second directly approaches a stationary sound source, S, which is emitting 1000 waves per second (1 kHz). In this example there is no change in wavelength. In one second, the observer will hear the number of waves emitted per second plus the number of waves which s/he has passed in the time (1000+100/0.34) = 1294.1 Hz.Note the interesting result - a stationary observer with moving source will not hear the same frequency as a would a moving observer with stationary source.
Pink noise is often produced by filtering white noise and has the same power within each octave. Narrow band analysis will show a fall in level with increasing frequency, but third-octave band or octave band analysis will be flat.
see Joseph S. Wisniewski's Colors of noise FAQ at:- http://capella.dur.ac.uk/doug/noisecols13.txt
A-weighting 2.4 2.12 8.1 absorption coefficient 4.1 4.2 accelerometer 3.1 acoustic energy 2.1 2.8 2.10 4.1 4.3 Acoustical Society of America 2.4 http://asa.aip.org/ active noise control 6.1 active vibration control 3.3 addition of sound 2.5 air absorption 2.9 ANC 6.1 atmospheric attenuation 2.9 atmospheric pressure 2.1 2.11 audibility 2.1 2.12 column speaker 6.3 concert pitch 6.6 dB(A) 2.4 8.1 decibel (dB) 2.2 2.3 2.4 Doppler effect 6.10 dynamic vibration absorber 3.3 ear 2.1 2.2 2.6 2.7 http://oto.wustl.edu/cochlea/ elastic structures 6.9 equal temperament 6.6 6.7 equivalent continuous sound level 2.4 focusing sound 6.3 frequency 2.1 2.4 2.12 6.6 6.7 hearing conservation 2.7 http://www.globaldialog.com/~nhca/index.html hearing damage 2.6 2.7 Helmholtz resonator 6.5 historical notes 2.4 2.12 insulation 4.3 4.4 4.5 interference 6.3 interval (music) 6.6 6.7 inverse square law 2.9 just intonation 6.7 Leq 2.4 logarithmic scale 2.2 2.3 loudness 2.1 2.2 2.12 loudspeaker 2.1 6.3 longitudinal wave 2.1 Lw 2.10 major and minor keys 6.7 masking 2.12 mel 6.6 musical scale 6.6 6.7 ocean sound velocity 2.11 octave 6.6 6.11 pascal 2.1 2.2 2.8 passive noise control 6.1 6.5 peak level 2.3 phon 2.12 physical constants http://physics.nist.gov/PhysRefData/contents.html Pierce, George W 2.4 pink noise 6.11 pitch 6.6 6.8 resonance 6.5 6.8 reverberation time 4.1 Sabine, Wallace C 4.1 semitone 6.6 6.7 sone 2.12 sonic boom 6.2 sonoluminescence 6.4 sound 2.1 sound absorption 4.1 4.2 4.3 sound cancellation 6.1 sound decay 2.9 sound insulation 4.3 4.4 4.5 sound intensity 2.2 2.8 sound intensity meter 2.8 sound level 2.4 2.5 2.12 sound level meter 2.3 2.4 2.8 2.12 sound power level 2.10 sound pressure 2.1 2.2 sound pressure level 2.3 2.4 2.5 speech 6.6 6.8 speaker 2.1 6.3 speed of sound 2.1 2.11 6.8 6.10 structural acoustics 6.9 supersonic 6.2 tapping machine 4.4 third-octave band 6.11 tinnitus 2.6 2.7 ultrasound 2.9 ultrasound scans 2.7 velocity of sound 2.1 2.11 6.8 6.10 vibration 2.1 2.7 3.1,3.2 vibration control 3.3 voice 6.6 6.8 wave 2.1 weighting 2.4 2.12 8.1 white finger 2.7 white noise 6.11
For A-weighting: A(f) = 12200^2 f^4 ------------------------------------------------------------------ (f^2 +20.6^2) (f^2 +12200^2) (f^2 +107.7^2)^0.5 (f^2 +737.9^2)^0.5
The weighting in dB relative to 1000Hz is now given by A(f) 20 lg ------- note: A(1000) = 0.794 A(1000)In tables, octave and third-octave frequencies are given as nominal values, for example 1250 Hz or 2500 Hz. Ideally weightings should be calculated for the exact frequencies which may be determined from the formula 1000 x 10^(n/10), where n is a positive or negative integer. Thus the frequency shown as 1250 Hz is more precisely 1258.9 Hz etc
Please let me know if any information in this list needs amending.
Argentina Argentina Acoustical Association Asociacion de Acusticos Argentinos c/o Prof A. Mendez, Laboratorio de Acustica, Camino Centenario Y 506, 1897 - Gonnet, Argentina Tel: +54 21 84 2686 Fax: +54 21 71 2721 e-mail: acustica@isis.unlp.edu.ar Australia Australian Acoustical Society Private Bag 1, Darlinghurst, NSW 2010 Tel: +61 2 331 6920 Fax: +61 2 331 7296 Austria Austrian Acoustics Association c/o Prof Ewald Benes, Technische Universitat Wien, Institut fur Allgemeine Physik, Wien, Austria Tel: +43 1 58801-5587 Fax: +43 1 5864203 Belgium Belgian Acoutics Assosciation (ABAV) Av. P Holoffe 21, 1342 Limelette, Belgium Tel: +32 2 653 88 01 Fax: +32 2 653 07 29 e-mail: bbri.lim@pophost.eunet.be Brazil Sociedade Brasileira de Acustica Attn Prof Samir Gerges, Universidade Federal de Santa Catarina, Departamento de Engenharia Mecanica, Campus Univeritario, C.P 476 CEP 88040-900, Florianopolis - SC, Brazil Tel: +55 48 2344074 Fax: +55 48 2341519 e-mail: gerges@mbox1.ufsc.br Canada Canadian Acoustical Association PO Box 1351, Station F, Toronto, Ontario, M4Y 2V9, Canada Tel: +1 514 343 7559 or +1 613 993 0102 Chile Sociedad Chilena de Acustica San Francisco # 1138, Santiago, Chile. Tel/Fax: +56 2 555 63 66 or +56 2 551 79 20 e-mail: acusticos@entelchile.net with copy (Cc) to: crooke@cmet.net China (PRC) Acoustical Society of China 17 Zhongguancun St., Beijing 100080, China Czech Republic Czech Acoustical Society Technicka 2, 166 27 Prague 6, Czech Republic. Tel: +42 2 24352310 Fax: +42 2 3111786 e-mail: csas@feld.cvut.cz Denmark Acoustical Society of Denmark c/o Department of Acoustic Technology, Bldg. 352 - Technical University of Denmark, DK-2800 Lyngby, Denmark Tel: +45 4588 1622 Fax: +45 4588 0577 e-mail: atc.das@dat.dtu.dk Finland Acoustical Society of Finland c/o Helsinki University of Technology, Acoustics Laboratory, Otakaari 5 A, FIN-02150 Espoo, Finland Tel: +358 9 451 2499 Fax: +358 9 460 224 e-mail: akustinen.seura@hut.fi France French Acoustical Society Societe Francaise d'Acoustique 23 avenue Brunetiere, 75017 Paris, France Tel +33 1 48 88 90 59 Fax: +33 1 48 88 90 60 e-mail: sfa@cal.enst.fr Germany German Acoustical Society Deutsche Gesellschaft fur Akustik c/o Department of Physics Acoustics, University of Oldenburg, D-26111 Oldenburg, Germany Tel: +49 441 798 3572 Fax: +49 441 798 3698 e-mail: dega@aku.physik.uni-oldenburg.de Greece Hellenic Acoustical Society Patision 147, 112 51 Athens, Greece Tel or Fax: +30 1 8646 065 Hong Kong Institute of Acoustics PO Box 7261 Hong Kong Fax: +852 2886 3777 e-mail: hkioa@hk.super.net Hungary Scientific Society for Optics, Acoustics... (OPAKFI) Fo utca 68, H-1027 Budapest, Hungary Tel/Fax: +36 1 202 0452 e-mail (c/o Andras Illenyi): illenyi@sparc.core.hu India Acoustical Society of India c/o Dr S Agrawal, CEERI Centre, CSIR Complex, Hillside Road, New Delhi-110012, India Tel: +91 11 5784642 e-mail (c/o National Physical Lab): Agrawals%npl@sirnetd.ernet.in Italy Italian Association of Acoustics Associazione Italiana di Acustica via Cassia 1216, 00189 Roma, Italy Tel: +39 6 30365746 Fax: +39 6 30365341 e-mail: aia@idac.rm.cnr.it Japan Acoustical Society of Japan Nippon Onkyo Gakkai 4th Floor, Ikeda Building, 2-7-7 Yoyogi, Shibuya-ku, Tokyo, Japan Tel: +81 3 3379 1200 Fax: +81 3 3379 1456 Korean Republic The Acoustical Society of Korea, c/o 302-B, The Korean Federation of Science and Technology, 635-4, Yeoksam-dong, Kangnam-gu, Seoul-city, 135-080, Rep. of Korea Tel: +82 2 565 1625 Fax: +82 2 569 9717 Mexico Mexican Institute of Acoustics Instituto Mexicano de Acustica c/o Sergio Beristain, P.O. BOX 75805, Col. Lindavista 07300 Mexico, D.F. Tel +52 5 682 28 30 Fax: +52 5 523 47 42 e-mail: SBERISTA@vmredipn.ipn.mx Netherlands Netherlands Acoustical Society Nederlands Akoestisch Genootschap Postbus 162, NL-2600 AD, Delft, Netherlands Tel: +31 15 26 92 442 Fax: +31 15 26 92 111 e-mail: nag@tpd.tno.nl New Zealand New Zealand Acoustical Society c/o J. Quedley, CPO Box 1181, Auckland, New Zealand Tel: +64 9 623 3147 Fax: +64 9 623 3248 e-mail: mms@bitz.co.nz Norway Acoustical Society of Norway Norsk Akustisk Selskap c/o Lydteknisk senter-NTH Sintef Delab, N-7034 Trondheim, Norway Tel: +47 73 59 43 36 Fax: +47 73 59 14 12 e-mail: sverre.stensby@delab.sintef.no Peru Acoustical Society of Peru Sociedad Peruana de Acustica Garcilazo de la Vega 163, Salamanca de Monterrico, Lima 3, Peru Tel: +51 1 4351151 Fax: +51 1 4675625 e-mail: cjim@net.cosapidata.com.pe Poland Polish Acoustical Society Polskie Towarzystow Akustyki Instytut Akustyki, Uniwersytet Adama Mikiewicz, ul J.Matejki 48/49, 60-769 Poznan, Poland Tel or Fax: +48 61666 420 e-mail: ula@phys.amu.edu.pl Portugal Portuguese Acoustical Society SPA - CAPS/Instituto Superior Tecnico, Av. Rovisco Pais 1096 Lisboa CODEX, Portugal tel: +351 1 841 9393/39 fax: +351 1 352 3014 e-mail: capsist@alfa.ist.utl.pt Romania Romanian Acoustical Society Societatea Romana de Acustica c/o Nicolae Enescu, Universitatea Politehnica Bucuresti, Splaiul Independentei nr. 313, 77206 Bucuresti, Romania Tel: +40 1 4101615 Fax: +40 1 4104488 e-mail: enescu@cat.mec.pub.ro Russia Russian Acoustical Society 4 Shvernik ul, Moscow, 117036 Russia Tel: +7 095 126 7401 Fax: +7 095 126 8411 e-mail: bvp@asu.acoins.msk.su Singapore Singapore Acoustics Society c/o W Gan, Acoustical Services Pte Ltd 209-212 Nanyang Ave, NTU, Singapore 2263 Fax +65 791 3665 e-mail: chenzhen@pacific.net.sg Slovakia Slovak Acoustical Society c/o Prof Stefan Markus, Racianska 75, PO Box 95, 830 08 Bratislava 38, Slovakia Tel: +42 7 254751 Fax: +42 7 253301 e-mail: markus@umms.savba.sk South Africa South African Acoustics Institute c/o Dr Fred Anderson, P.O. Box 912-169, Silverton, South Africa, 0127 Tel or Fax: +27 12 832857 e-mail (c/o Andersen Technology): pak03486@pixie.co.za Spain Spanish Acoustical Society Sociedad Espanola de Acustica Serrano 144, E-28006 Madrid, Spain Tel: +34 1 5618806 Fax: +34 1 4117651 e-mail: a.perezlopez@mad.servicom.es Sweden Swedish Acoustical Society Svenska Akustiska Sallskapet c/o Ingemansson AB, Box 47 321 S-100 Stockholm, Sweden Tel: +46 8 744 5780 Fax: +46 8 18 26 78 e-mail: sas@ingemansson.se Switzerland Schweizerische Gesellschaft fur Akustique Societe Suisse d'Acoustique Postfach 251, 8600 Dubendorf Tel: +41 1 823 4743 Fax: +41 1 823 4793 e-mail: kurt.heutschi@empa.ch Turkey Turkish Acoustical Society - TAS Y.T.U. Mimarlik Fakultesi Yildiz, 80750, ISTANBUL/TURKEY Tel: +90 212 259 70 70 ext: 2772 Fax: +90 212 26105 49 e-mail: takder@ana.cc.yildiz.edu.tr UK Institute of Acoustics 5 Holywell Hill, St Albans, Herts, AL1 1EU, UK Tel: +44 1727 848195 Fax: +44 1727 850553 e-mail: Acoustics@clus1.ulcc.ac.uk USA Acoustical Society of America 500 Sunnyside Blvd., Woodbury, NY 11797, USA Tel: +1 516 576 2360 Fax: +1 516 576 2377 e-mail: asa@aip.org