6th international congress on noise as a public health problem—nice, july 1993

ACOUSTICAL NEWS FROM ABROAD

Walter G. Mayer Physics Department, Georgetown University, Washington, DC 20057

,

Maurice J. M. Jessel ß 1921-1993

Maurice J. M. Jessel, a Fellow of the Acoustical Society of America and a pioneer in active noise control, died 5 April 1993 at his home in Marseilles, France, at age 71. He was the author of numerous papers and a book, Acoustique Th•orique, Propagation et Holophonie (Mason et Cie, Paris, 1973). From 1978 to 1991, he was the French editor of Acustica a journal that published an extensive encomium in 1991 on the

occasion of his 70th 'birthday. Hewas scientific advisor to the

Groupe des Acousticiens de Langue Fran•aise (which has become the

Soci6t6 Fran•aise d'Acoustique). His work has inspired collaborators in Japan and the United States as well as in Europe.

Maurice Jessel was born at Mulhouse, Alsace, on 11 June 1921. Because of interference by World War II, he received his education in fragments, some in Alsace, Limoges and Auvergne, finally obtaining a degree in mathematics from Strasbourg in 1947. In 1962, he received a doctorate from the University of Paris in physical science. His disserta- tion, entitled "A Contribution to Huygens' Principle and to Diffraction," was a rigorous formulation of Huygens' principle, namely, that the field of a source can be identically replicated by treating each infinitesimal seg- ment of a wave front as a new source. He showed that these Huygens' sources have a cardioid radiation pattern. From this he drew the inference that cancellation sources on a surface enveloping a primary source will act as absorbers if they have a cardioid radiation pattern. This suggested a means for active noise cancellation. He obtained a French patent on this invention in 1966.

Maurice Jessel worked successively at the Centre National d'Etudes des T616communications as a Research Scholar (1947-1951); at the So- ci6t6 Fran•aise Radio61ectriquemCompagnie de T616graphie Sans Fil as an Engineer (1951-1953); at the Ecole Sup6rieure de Physique et de Chimie Industrielle of the City of Paris as Assistant Head of the General Electric Laboratory ( 1955-1965); at the Centre National de la Recherche Scientifique, in the group on theoretical physics in the Henri Poincare Institute as a Research Associate (1955-1965); and at the Centre Na- tional de la Recherche Scientifique at Marseilles in the Laboratory of Mechanics and Acoustics (LMA), first as Master of ReSearch (1965) and then as Director of Research (1985 until his retirement in 1989).

The numerous works of Maurice Jessel covered several areas. First, ' he studied electromagnetic waveguides and cavities both theoretically and experimentally. It was from this work that the idea came to him of for- malizing Huygens' principle using Poincar6's method of partitioning. Next, he generalized his method to apply to any kind of field whatever and applied his results to acoustics: diffusion, radiation, acoustic holog- raphy, and, above all, active acoustic absorption (antinoise). In this effort he was helped from the theoretical viewpoint by G6rard Mangiante and Georges Can6vet (JMC group) and from experimental investigations by Th6ophile Ang61ini and his team. This work is known as the "JMC Method."

Jessel's work not only developed a more rigorous formulation of Huygens' principle in response to the objections of Louis de Broglie, but, in fact, also gave birth to a new method of mathematical physics. This method is sufficiently general to be applied to any type of field whatever, provided only that the propagation process is known. The scope of appli- cation has been extended to fields as diverse as chemistry, biology, and the social sciences. In parallel to these studies, Jessel has clarified certain points of nonlinear and quantum acoustics.

He leaves his wife, two children, and grandchildren. He will be remembered with affection by all who knew him.

OLIVER L. ANGEVINE

GERARD MANGIANTE

Angevine Acoustical Consultants, Inc. East Aurora, NY 14052

European Mechanics Society established

Earlier this year the European Mechanics Council adopted statutes and procedures to effect its transformation into Euromech--European Mechanics Society. The present Council will act as the Interim Council of the new society until 1 January 1995 at which time it will be replaced by a new Council to be elected in 1994. The Interim Officers are: D. G.

Crighton at the University of Cambridge, President; B. Lundberg of Upp- sala University, Secretary-General; and E.-A. Miiller of G/Sttingen Uni- versity, Treasurer. David Crighton is a Fellow of the Acoustical Society of America.

The Council has overall responsibility for a number of Euromech Meetings, particularly the Euromech Colloquia, and the European Con- ferences on Solid Mechanics, Fluid Mechanics, Turbulence, and Nonlin- ear Oscillations. The dates and venues of these and other Euromech-

sponsored meetings of interest to acousticians are listed in the Calendar. Additional information can be obtained from the Secretary-General: Bengt Lundberg, School of Engineering, Uppsala University, Box 534, S-75121 Uppsala, Sweden,

European Conference on Underwater Acoustics---Call for papers

The Second European Conference on Underwater Acoustics will be held 4-8 July 1994 at the Technical University of Denmark, Copenhagen. The meeting is sponsored by Commission of the European Communities, the Federation of Acoustical Societies of Europe, and the acoustical societies or associations of France, Germany, Italy, Spain, and the United Kingdom. Invited, contributed, and poster papers at the conference will cover all areas of underwater acoustics, in particular the most recent developments in the fields of Arctic acoustics, ambient noise, reverbera- tion, modeling and measurements, calibration, transducers, and other areas including underwater communication, sonar in fisheries, acoustics in marine geology and geophysics, etc. In addition, workshops and special sessions are planned, including sessions of particular interest to represen- tatives from industry. A program for accompanying persons is planned.

The conference language will be English, and no simultaneous trans- lations will be available. There will be a conference fee of 240 ECU.

Additional information can be obtained from the Secretariat, DTH-- Department of Industrial Acoustics, Building 425, 2800 Lyngby, Den- mark.

6th International Congress on Noise as a Public Health Problem---Nice, July 1993

In 1968, a conference on Noise as a Public Health Hazard, orga- nized by the American Speech and Hearing Association for the purpose of summarizing the knowledge about the effects of noise for the benefit of legislators preparing regulations to limit noise exposure, was held in Washington. Forty-one presentations in 2 days pretty well covered most aspects of the effects of noise. Five years later, a second conference, now called a "Congress," involving 65 presentations over a period of 5 days, was held in the late Dubrovnik, but with "Hazard" in the title replaced by "Problem." At that time, it was decided to form a quasipermanent orga- nization, the International Commission on the Biological Effects of Noise

3026 J. Acoust. Soc. Am. 94 (5), November 1993 0001-4966/93/94(5)/3026/4/$6.00 ¸ 1993 Acoustical Society of America 3026

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TABLE I. The distribution of invited and contributed papers among the various teams.

Invited Contributed

Team Title reviews papers Total

1 Noise-induced Hearing Loss 14 a 40 54 2 Noise and Communication 5 13 18

3 Nonauditory Physiological Effects 5 14 19 4 Effects of Noise on Performance 4 12 16

5 Sleep Disturbance 10 a 7 17 6 Community Response (Annoyance) 5 54 59 7 Effects on Animal Life 5 11 16

8 Combined Effects 4 13 17

9 Standards and Regulations 10 16 26 Total 62 180 242

aIncludes 5 workshop participants.

(ICBEN), composed of six "teams" each of which dealt with a specific effect, and that a Congress should be held every 5 years to summarize progress in the fields, to be held wherever someone would volunteer to host it. Succeeding Congresses took place in Freiburg in 1978 (105 presentations), in Turin in 1983 (101 invited papers and 44 contributed posters, and in Stockholm in 1988 (58 invited reviews and 137 contributed papers). The sixth of these Congresses was attended by over 400 people from 32 countries in Nice, France, on 5-9 July, 1993, with a total of 62 invited plenary papers and 180 contributed poster and precise/ poster presentations in sometimes parallel sessions. The Congress was held in the Nice Acropolis, which turned out not to be an ancient Greek ruin atop a hill but a completely modern congress center with excellent facilities.

The distribution of invited and contributed papers among the various teams, now grown to 9 in number, is shown in Table I. The field is clearly dominated by hearing loss and annoyance. Although the total number of papers has increased fairly linearly by 40 at each succeeding Congress, really new information has not kept pace. Indeed, I suspect that of those five of us who have given presentations at each of the Congresses, only one, who believes that regulations should be established even if the evidence relating noise exposure to a specific effect is equivocal, would say that material progress has been made in 25 years toward our goal of understanding and controlling the effects of noise exposure.

The proceedings will comprise three volumes. Volume 1 (83 pp.) contains short summaries of the invited papers, the expanded versions of which will constitute Volume 3. Volume 2 (672 pp.) consists of all the contributed papers and posters. Volumes 1 and 2 were distributed at registration, but of course there was no time to digest this vast amount of material until after the Congress. However, after studying these volumes and integrating my notes, I hope to outline some of the high points of the meeting. In the following, numbers in brackets indicate pages in Volume 1, those in parentheses designate pages in Volume 2.

Team 1: Noise-induced Hearing Loss. Discovery of the active process in the cochlea in 1978 continues to affect speculation about the nature of temporary and permanent noise-induced threshold shift (TTS and NIPTS). It is likely that the active process is involved in the "toughening" effect of a moderate exposure that reduces the damage from a sub- sequent severe exposure. This effect was the subject of an excellent workshop [62-66] in which all known mechanisms involving central control of vulnerability to TTS and PTS were discussed. Unfortunately, there is as yet no evidence that any such toughening occurs in man, but only in laboratory animals--and then mostly in animals previously unexposed to any high-intensity noise. Despite a considerable growth in knowledge about cochlear function in the past 5 years, we still are not sure of the locus of TTS and NIPTS.

Individual papers held a variety of conclusions. An ordinary earplug that is fitted well is sufficient to reduce the hazard to hearing from impulse noise to zero [43], at least up to an atmosphere of overpressure ( 194 dB SPL) (255). Three papers dealt with cancellation techniques for reducing low-frequency noise (83, 193, 447). A comparison of three methods used in the UK for deducing NIPTS from measurements of exposures and Hearing Threshold Levels (HTLs) using ISO 1999 (43) failed to con- sider the fact that all three are inaccurate because they assume that HTLs

of 18- to 30-year-olds are zero instead of 3-5 dB, perhaps nearly 10 dB at 6000 Hz. However, HTLs of 25 dB or greater in 18-year-olds are no more prevalent now than 20 years ago (119). There were the inevitable papers that present sound level measurements that suggest that, for example, music should be hazardous to hearing (79, 165), but without data show- ing that it is. One finds plenty of "noise notches" in audiograms of persons with no known noise exposure (109) outside of the sociacoustic noises of everyday life, in which Spain averages an Leq(241•) of 74 dBA, with 10% of exposures over 80 dBA (367). The van Dishoeck audiometer, which measures auditory thresholds by sweeping frequency at a constant level, has been reinvented (87) in order to facilitate measurement at ultrahigh frequencies (8-20 kHz). However, there remains no evidence that NIPTS can occur first in that ultrahigh-frequency region rather than at 3, 4, or 6 kHz (53). Overflights by low-flying military aircraft pose no hazard to hearing (101). Finally, guinea pigs exposed for 12 weeks to textile-mill noise (16 h/day, 5 days/wk) reached an asymptote of NIPTS after 4 weeks (127), which raises serious doubts about the validity of the micro- trauma theory of growth of NIPTS, in which each day's exposure is assumed to produce a finite loss even though that loss may be so small as to be unmeasurable.

Team 2: Noise and Communication. Masking of speech by noise in normal-hearing individuals has been thoroughly studied for half a cen- tury, so progress in the last 5 years in noise and communication has been made only in detection of danger signals [16-18] and in perception of speech by persons with high-frequency losses [ 19]. The salience of danger signals depends on frequency and on the number and speed of repetitions as well as on the loudness, higher values of each parameter eliciting a greater probability of response [20].

Team 3: Nonauditory Physiological Effects. Considerable attention has been given to the problem of noise as a stressor that may produce some lasting changes in the cardiovascular system; however, there is still no compelling evidence to support this hypothesis [22] (283, 465, 513). High-powered epidemiological statistics are needed to demonstrate any correlation between blood pressure and either noise exposure [25] or HTL (461), and of course correlation does not prove causation even then. Noise exposure has no effect on the immune system (509) nor on psy- chiatric symptoms in people near airports except perhaps in those individuals who are most annoyed by the noise (473). A chart suggesting exposure limits that will guarantee no effect on the pulmonary system has been developed (485), but these limits are of course much higher than for prevention of NIPTS, e.g., 190 dB for 1 min. A generalization that seems to be consistent with all the data is that an exposure that causes no NIPTS will not cause any other physiological aftereffect of a permanent nature [26]. Persons who indicate, by self-report instruments, that they are psy- chologically "noise sensitive" do also show greater physiological reactiv- ity to a given sound (481 ).

Team 4: Noise and Task Performance. The ambiguity that has af- flicted this area continues; some noises impair performance on some tasks, other noises may improve performance. When the noise is speech, it is more disruptive than is random noise (557), perhaps because it is more distracting [38]. This appears to be related to the fact that noise, particularly low-frequency noise (539), does consistently interfere with selec- tive attention (multiple-task conditions) (535). Accident rate in textile workers was actually higher in a lower noise level (489), contrary to earlier studies; however, the workers in the higher noise were older and more experienced, so one should avoid concluding that noise in this case is a good thing.

Team $: Sleep Disturbance. Research on sleep disturbance is very expensive, so everyone engaged in it feels obligated to publish something. However, despite 5 review papers, 7 contributed papers, and a workshop, there has been little progress toward accurate prediction of sleep disrup- tion or of aftereffects such as "tiredness" the next day. Idiosyncratic characteristics of individuals still appear to be more important than the physical dimensions of the noise in determining disturbance of the sleep process [48-50].

Team 6: Community Response. The same is true for the annoyance aroused by noises, which is assumed to be the major factor that deter- mines the degree of community reaction. Individual differences in the degree of annoyance associated with a given noise are huge; there are few sounds that do not annoy someone some time. The problem of controlling noise to avoid any annoyance is therefore insolvable, which may be why 54 contributed papers dealt with it.

So the search continues for the relevant acoustic parameters of the sound and characteristics of individuals, and for the appropriate weight-

3027 J. Acoust. Soc. Am., Vol. 94, No. 5, November 1993 Acoustical News from Abroad 3027


ing to be applied to this myriad of factors in order to predict annoyance or community action. The level of background (ambient) sound is of minor importance [58], at least until it gets to the speech interference range; even then, if a particular noise is reduced in level, other unwanted sound sources--perhaps more annoying--may now become audible [61]. Annoyance from gunfire near shooting ranges was nearly independent of the number of shots (605), in marked contrast to aircraft noise, where the number of overflights is consistently more important than peak level. For a given value of Lan (the Leq(24h ) with a 10-dBA penalty for night noises), gunfire in western Europe is consistently more annoying than transportation noises [59]. Among the latter, the order of annoyingness is aircraft noise > highway noise > train noise [60], an order just the reverse of that for sleep disturbance (559). Two papers discussed annoyance from a couple of new low-frequency sources: heat pumps (407) and wind tur- bines (235). An interesting observation is that, except for gunfire, a change in the noise dose in a particular community engenders a greater change in annoyance than would be predicted from the "standard" dose- response curve that was derived from measuring annoyance at different places (585, 427).

Team 7: Effects on animals. Most of the research in this area in-

volved noise from aircraft (usually military) and showed negative results. The kit fox and its chief prey, the kangaroo rat, are not affected [27], and deer [28] and caribou [29] are not harmed either, although watch dogs appear to become less vigilant (259). Not surprisingly, whales and dol- phins stop talking in the presence of a strong (220 kB at the source) 57-Hz underwater sound (260), but they did not leave the area during the 7 days of exposure.

Team 8: Combined Effects. In view of the numerous noxious (or even neutral) agents that could conceivably have a synergistic effect when combined (or preceded or followed) by noise, it is surprising that so few papers were presented on the topic. Part of the problem has always been in defining when an interaction is truly synergistic and not simply additive (277). No synergistic agent was reported at the Congress that is as effec- tive as carbon monoxide in increasing NIPTS, as reported in Stockholm. However the fact that CO is a potent synergistic agent has led to considerable research to determine if, of workers in noise, the smokers have more hearing loss than nonsmokers. Two papers dealt with this question (291,317); both found a slightly greater hearing loss in smokers, but the magnitude of the difference was so small that it would have no practical significance for anyone but an epidemiologist. Having a cold has no effect on task performance in noise (311 ). The same is true for vibration (279). Likewise, vibration had no effect on drowsiness while driving (523). Pre- diction of the annoyance produced by a combination of steady and impulse noise is a complex process that is not solved by a simple decibel correction (597).

Team 9: Regulations and Standards. We now leave the scientific aspect of the Congress. Team 9, a team added in 1988, deals with the process of applying---or ignoring--the complex scientific results in order to develop control of noise sources and/or noise exposures. Their 26 papers described the oversimplifications used in various countries. Every- one seems to have accepted the principles that the use of A-weighting is the only way to assess noise with differing spectra, that a complicated temporal pattern can be represented by the equivalent level of the exposure (except for the USA, in controlling hearing hazard), and that no sound should exceed 140 dB peak SPL. These principles are accepted because they are almost always overprotective of hearing, which is not only politically correct but even practically correct. If the limits of noise exposure based on the foregoing principles are strictly observed, there should be no grounds for suing for hearing loss by any employee, and millions of dollars will be saved; it is pointed out that in Australia, the cost to an employer of fighting (and usually losing) a single suit for hearing loss is often greater than the cost of noise reduction [50].

Regulations designed to reduce community reaction to noise have a greater variety than those protecting hearing. Most of them attempt only to limit sound levels--the levels of a specific source, or the level at prop- erty boundary lines--with no consideration of duration. When more complex measures are used that do take duration into account, such as Ldn, the problem of enforcement becomes insurmountable•if Ldn at a particular place exceeds 65 dBA, and there are many sound sources (such as transportation noises) contributing to that exposure, which source is responsible for exceeding the limit and must therefore be reduced? In France, Germany, and Switzerland, the answer that has been adopted is that all sources are responsible; since commercial aircraft cannot become quiet enough to eliminate community annoyance, every aircraft is fined (a

so-called "noise tax") by an amount that depends on the type of aircraft, its weight, the time of day, and the overall activity at the airport con-

ß cerned (659). As it happens, the Nice airport has few enough flights that no noise

tax is exacted, so we were all able to get home tax-free.

W. DIXON WARD

University of Minnesota Minneapolis, MN 55455

Calendar

Below are announcements of meetings to be held abroad. Entries preceded by an * are new or updated listings with contact addresses given in parentheses. Month/year listings following other entries refer to issues of the Journal which contain full calendar listings or meeting announcements.

November 1993

14-18

18-19

December 1993

2-4

7-9

15-17

January 1994 30-5

February 1994 27-2

April 1994 5-7

11-14

18-21

May 1994 2-4

12-15

June 1994

6-8

13-15

July 1994 3-7

5-8

18-21

19-21

International Violin Making Competition, Prague. 7/93

*Materials used in Acoustics, Lille, France. (B. Ha- monic • l'Isen, 41 bd Vauban, 59046 Lille, France)

*French Audiology Congress, Bordeaux, France. (Labo d'Audiologie Exp6rimentale, H6pital Pelle- grin, 33076 Bordeaux, France) British Medical Ultrasound Society Meeting, East- borne. 9/93

Symposium on Ocean Electronics, Cochin. 7/93

*2nd Winter School on Acoustic Diffusion, Cauterets, France. (Miss M. Talmant,GPS•Tour 23, 2 place Jussieu, 75251 Parris Cedex 05, France)

96th AES Convention, Amsterdam. 7/92

*Automatic Speaker Recognition, Identification, and Verification, Martigny, Switzerland. (IDIAP, P.O. Box 609, 1920 Martigny, Switzerland) *Advanced Techniques in Structural Acoustics, Manchester, U.K. (G. R. Wickham, Department of Mathematics, University of Manchester, Oxford Road, Manchester M13 9PL, U.K.) Acoustics '94, Salford. 11/92

3rd French Congress on Acoustics, Toulouse. 5/93 *Effects of Noise on Hearing, G6teborg, Sweden. (A. Axelsson, Department of Audiology, Sahlgren's Hos- pital, 413 45 G6teborg, Sweden)

Scandinavian Acoustical Meeting, Aarhus. 3/93 *International Congress on Air- and Structure-Borne Sound and Vibration, Montr6al, Canada. (Congress Secretariat, Mechanical Engineering Department, Auburn University, AL 36849-5341, USA)

Congress in Audiology, Halifax. 5/93 *5th European Turbulence Conference, Sienna, Italy. (R. Benzi, Dipartimentodi Fisica, Universira di Roma, Via della Ricerca Scientifica 1, 00133 Roma, Italy) 5th International Conference on Recent Advances in

Structural Dynamics, Southampton. 9/92 Electronic Engineering in Oceanography, Cambridge. 7/93

3028 d. Acoust. Soc. Am., Vol. 94, No. 5, November 1993 Acoustical News from Abroad 3028


6th international congress on noise as a public health problem—nice, july 1993

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