Relevance of Noise Control for the Development of Acoustics  in the 20th Century 

By: Joachim Scheuren, Müller-BBM, Helmut.-A.-Müller-Str. 1-5, D 82152 Planegg, Germany 

Editors Note: This is an extended article from a presentation given at the INTER-NOISE 2024 article, from the same author. 

Introduction 

The history of acoustics dates back to the very beginning of human exploration of the world and its phenomena. This is quite natural because acoustical phenomena, acoustic perception and acoustic communication definitely belong to the basic prerequisites of higher life. Consequently, even if it was not called acoustics yet, acoustics was a matter of consequent research efforts since ancient times [1]. 

Over the centuries, the results of these efforts combined to partial completeness which, in the nineteenth century, then caused systematic research for full understanding of the underlying physics. This was achieved in the second half of the century by the outstanding work of Hermann von Helmholtz (“On the sensations of tone”, 1862, [2]) and Lord Rayleigh (“Theory of Sound”, 2 volumes, 1877 and 1878, [3], see figure 1) who were able to explore and explain a great variety of acoustic phenomena and mechanisms and to subject them to a closed theory, the theory of sound. Helmholtz himself stated that Rayleigh had given “a complete and coherent theory …. of sound …. with application of all the resources furnished by mathematics” without which “a really complete insight into …. the phenomena of acoustics is altogether impossible” [1]. Thus, mathematical physics had found their way into acoustics and this was conclusively crowned by the key work in Mathematical Physics of David Hilbert and Richard Courant (2 volumes, 1924 and 1937, [4]). 

Figure 1: Hermann von Helmholtz (with Helmholtz-resonator) and his book “Die Lehre von den Tonempfindungen” (on the sensations of tones, left) and Lord Rayleigh and his book “Theory of Sound” (right). 

With the complete theory of sound, physics of 19^th century had succeeded to provide a widely comprehensive and conclusive understanding of physical acoustics. However, as later again, this had the effect that acoustics was seen – and underestimated! – as a somehow completed discipline without new scientific challenges. But the challenges came with new progress in physics and technology. 

Based on previous articles of the author ([5]-[7]), the information to follow refers to a collection of 37 papers from 21 European countries given recently (September 2023) in a structured session “Activities in Acoustics of European Research Centers and Companies during the 20th Century” at Forum Acusticum in Torino [8]. 

Acoustics and Noise Control in the First Half of the 20^th Century 

The invention of the telephone by Philipp Reis (1861), the foundation of electrodynamics by James Clerk Maxwell (1864) and the evidence of electromagnetic waves by Heinrich Hertz (1886) caused a rapid development of electrical communications and broadcasting. As the transmission quality of acoustic signals crucially depended on the quality of acoustic (recording and reproduction rooms) and electroacoustic (microphones, loudspeakers storage etc.) components, this also caused a rapid development of room-acoustics and electro-acoustics including new measurement approaches and technologies [9]. 

Thus established, technical acoustics was the starting point for growing relevance and involvement of acoustic issues within the process of industrialization in the 20^th century. At first, this development focused on providing and supporting desired sounds (electric sound recording, transmission, -reproduction and distribution). Then, in addition to developing and extending worldwide broadcasting of sound signals via telephone and radio networks as well as tape and disc recordings, it was W.C. Sabine who was able to lay a solid foundation for targeted acoustic design and layout of auditory rooms to best adapt them to the perception of speech and music. 

However, reduction of undesired sounds by technical means was increasingly recognized as an important discipline too, indispensable even for progressive mechanization of our world. Significantly interested circles thus were sure in the early 20^th century already that noise abatement was a public duty, being claimed for instance by the “Society for the Suppression of Unnecessary Noise” (founded 1906 in New York) and by the first German Noise Abatement Society (founded 1908 in Hannover). 

Physical and technical acoustics tried to meet the respective requirements by successful research activities as well as by new findings and development results. Apart from complementing and completing the far-sighted frameworks of Helmholtz and Rayleigh, this led to increasingly systematic investigations of sound generating, sound transmitting and sound controlling mechanisms. Exemplary examples were 

• Berger’s mass law (1910) 

• Derivation and validation of practical approximation formulas and design rules 

• Introduction of “dB” (1920s) and “phon” (for loudness by Barkhausen, 1926, see figure 2) 

• Fundamental investigations on structure- and fluid-borne sound 

• Investigations and design of porous wedge absorbers for anechoic rooms 

• Derivation and experimental verification of coincidence effect by Cremer and Eisenberg (1942/48) 

• Development of a theory of tapping sound (Cremer) and development of hammering tapping sound generators for reproducible measurements (see figure 2) 

• Development and provision of versatile measurement technology and instrumentation using new tube technology 

• Development and provision (by literature) of theoretically and empirically well-founded state-of-the-art reports for the most important subdisciplines of technical acoustics. 

In total, in the middle of last century, technical acoustics may be described as a discipline which felt committed to the fascination of new technical possibilities (electro acoustics) and quality-conscious hearing requirements (room acoustics) but also to the (still) weak social awareness of detrimental noise effects (noise control). By orientating successive insight along the requirements of increasing mechanization, acoustics had been able to recommend itself as an important instrument of prudential engineering activities: Being formally associated with communications technology (electro-acoustics) or mechanical vibrations and waves (room-/building acoustics and noise control), technical acoustics was to become engineering acoustics [9]. 

But again, from a scientific point of view, acoustics was seen to be a widely completed discipline, lacking new scientific challenges. For young students making their choice for the field of their studies, acoustics just appeared to be old-fashioned and unattractive. But again, great challenges were there, ready to involve and further develop existing acoustic methods and skills. 

Acoustics and Noise Control in the Second Half of the 20^th Century 

The disastrous consequences and destructions of World War II had abruptly ended the successful work of many prestigious research institutions in Europe and many other parts of the world. The degree of destruction and the necessary extent of new beginning may become evident from the primitive simplicity of early after-war working tools in Germany. Figure 3 shows a first provisional test hall for acoustic measurements and a first mobile measurement car (trolley) as used by early staff members of acoustic institutions in Berlin in the very first after-war years.  

However, while research institutions were subject of new orientation and rebuilding, rapid housing reconstruction needed immediate competent acoustic support. Fast and cheap reconstruction methods ruthlessly uncovered deficits in knowledge and quality defects. Also, growing prosperity later implied increased demands for comfort and quality of life. Thus, noise reduction and acoustic comfort soon forced acoustics to be consequently involved in an interdisciplinary way with relevant engineering disciplines. Well prepared technical acoustics was driven to become engineering acoustics and noise control engineering.

Although the spectrum of noise control was flexibly varying from the very beginning, the main focus of activity changed from building acoustics in the fifties to industrial noise control in the sixties and transportation noise including rolling noise from the seventies on. This shall shortly be reviewed in the following. 

Building Acoustics 

Starting point in many countries were ambitious building programs aimed to use cheap and light building materials, soon with preference for prefabricated elements. However, without proper design rules this was likely to end up with poor acoustic quality. Consequently, research for better design rules soon was focused by up-to-date research institutions. Thus, reduction of noise and sound transmission in buildings was not only an issue for existing or rebuilt institutions but also for new research institutions to be founded. 

European Examples are the Institute of Technical Acoustics (ITA) at Technical University (TU) of Berlin (founded in 1954 and directed by Lothar Cremer, [9]) and the extension of an early acoustic lab (founded by Per Bruel in 1943/44) to an Institute for Applied Acoustics at Chalmers Technical University in Gothenburg (Sweden), led by Tor Kihlman, in the end of the sixties [10]. They both were strongly committed to scientifically support ongoing building activities. The extension of the Institute at Chalmers was strongly motivated even by a huge “million programme” to build one million flats in short time with newest building technologies [10]. 

In the US, similar acoustic laboratories had been newly formed, mostly within Electrical Engineering departments as at MIT in Cambridge in the late 40s ([11]).  

The practical orientation of such institutions in both, research and teaching, made them an ideal nucleus to cope with increasing demands for consultation and practical support in acoustic matters and problems. This was the hour of birth of independent acoustic consultancies like “Bolt Beranek & Newman” (BBN) in the US ([11]) or “Müller-BBN” (later Müller-BBM) in Germany ([12]). It was most typical for that era that both these offices had to prove themselves with demanding building projects, the new seat of the Unites Nations in New York City and prestigious auditoria in Munich and Stuttgart. 

The fact that building acoustic problems and activities were the predominant starting point for acoustic activities and institutions was impressively substantiated by the sequence of presentations at the before-mentioned structured session on the history of acoustics at Forum Acusticum 2023. As can be seen from many of the papers given in the proceedings [8], building acoustics has been the founding mission for many research- and technology-institutions as well as standard authorities in many European countries even in later years of 20^th century. 

Building acoustic activities often were linked with room acoustic design applications where sound isolation and noise control requirements had to be combined with optimal sound distribution requirements in auditoria. Successful design solutions for all these tasks depended on the availability of high-performance measurement rooms and equipment. Figure 4 shows two examples of pioneering work in room/building acoustics and for an anechoic measurement room. The first refers to the innovative Berlin Philharmonic Hall, where new acoustic concepts and elements were able to cope with new room concepts and to give them reference status in the end [9]. The second refers to an innovative anechoic room in Göttingen (Germany) which, in 1954, even served as cover photo for a special issue of the US-magazine “Life International” on “Germany, the awakening giant“ [13]. Many other examples of applications and tools can be found in [8]. 

Industrial Noise Control 

Next to architectural acoustics, industrial noise control soon appeared to be another relevant field of application and thus another dominant driving force for further developing the toolbox of practical engineering acoustics. Although the physics involved with these tasks were mostly well understood, it needed a lot of tests and measurements to find practicable models and to identify influential design parameters. This shall be illustrated here for two typical, representative examples [12]. 

The rigorous acoustic treatment of a thermal power station had shown in the fifties already that sound emission of large plants could be estimated by simple energy considerations which then allowed to meet achievable limit values. This was a key prerequisite for setting mandatory acoustic requirements for technical plants and installations because the predictable only can be planned.  

An early pilot project was a 50 MW thermal power station in Munich to be built in the fifties of last century in the middle of a Munich residential area. To be compatible with its residential environment it was required to be “inaudible” which meant not to increase the existing ambient noise level. There were no data bases with empirical values, no guidelines, no experiences – all this still had to be found and developed. Thus, all data, source levels of machinery as well as sound radiation, propagation and insulation characteristics including secondary transfer paths, all together with their dependency on design parameters, had to be determined from measurements and appropriate parametric models. And it worked: The thermal power station fulfilled all permit requirements and thus provided evidence that sound characteristics of industrial plants can be predicted and planned. 

But there was another branch of industrial plants which needed completely different approaches of noise control: petrochemical plants, typically spread over large areas in open air due to risks of fire and explosion. It was not possible therefore to apply enclosures around the plant or parts of it. 

The predominant opinion of the time was that noise emitted by so many complicated sources and mechanisms was not predictable and control measures therefore only applicable in retrospect, after commissioning. It took many arguments and demonstrations to convince the operating companies that thorough determination of the sound power emitted by the great number of single aggregates would allow to predict the noise impact in the neighborhood. And it needed many basic investigations and measurements to provide all necessary data and influencing parameters (see figure 5 as an example). 

In the early seventies, stringent but balanced control measures at all relevant sound sources (e.g. primary measures at valves and fans) but also at appropriate sound transmission paths (e.g. secondary measures like encapsulation, blow-out or inline silencers) altogether were able to reduce the radiated sound power of petrochemical plants – in spite of increased plant performance – by some 15 dB(A). This means that the area exposed to a particular sound level could be reduced by more than 90% – an impressive demonstration of the potential of consequent noise control. Such pilot projects provided evidence that even large industrial installations could be operated in an environmentally compatible way in densely populated areas. 

 Transportation and Traffic Noise Control 

Among the many contributions to vehicle acoustics and traffic noise control, early pioneering work was applied to provide predictive estimates of traffic noise for roads and rails. As with the before-mentioned thermal power station, any tools for predictions such as in noise maps were not available, they still had to be developed. It took decades to complete, implement and provide, step by step, the large toolbox of clear standards, guidelines, design rules and extensive software packages we are used to have today [12]. 

An example of such an early step is shown in figure 6 (left) where a noise map (left) has been calculated and drawn by hand from plausible, slide-rule-based estimates of sound propagation losses in a given landscape. Again, such calculations were the basis for clear and binding rules as fixed in relevant regulations, guidelines and software packages later. Figure 6 also shows one of the first noise protection walls (built for noise protection reasons only) in Germany (right). 

Instead of passively reducing the incidence of noise it would be much more efficient to actively reduce the radiation, the generation of noise. Of course, this was known from the very beginning of noise control already but to do so it is important to adequately understand the generation of sound. However, as rolling noise is the dominant noise source for road and railway noise, the respective generation was not sufficiently understood yet in the first after-war decades of last century. It took until the seventies that rolling noise was investigated systematically and it took some more decades until the mechanisms involved were sufficiently understood to provide reliable models and design rules for low noise wheel/rail constructions, low noise tires and low noise road surfaces. 

Summary of Technical Development 

In the second half of 20^th century, the development of technical and engineering acoustics was strongly driven by the needs of noise control and sound quality requirements. As shown above, 

• the 1950s were able to provide fast reconstruction, fulfilling acoustic requirements in spite of low-cost construction methods (focus on building acoustics), 

• the 1960s were able to show that industrial plants may be run with environmental compatibility in highly populated areas even (focus on industrial noise control), 

• the 1970s introduced passive ways to reduce traffic noise exposure and successfully started systematic investigations to understand and reduce rolling noise (focus on traffic and rolling noise control). 

Of course, the driving force of noise control and sound quality was accompanied by many more efforts and progress in various fields of acoustics like computational acoustics, hydro acoustics, flow acoustics, ultra-sound, medical acoustics, psychoacoustics and – very important – acoustic measurement and computer technology. But most of them may be categorized by their common target to find ways how to control sounds. And among the sounds to be controlled, unwanted sounds or noise played and play a major role. So, it can be stated that noise control was a relevant driving force for the development of acoustics in the second half of last century. 

Self-Organization in Acoustical Associations 

The technical development as described above was able to establish engineering acoustics as a necessary interdisciplinary engineering discipline. This technical self-confidence encouraged the self-confidence of acoustics as a whole. Following the example of the acoustical Society of America (ASA), which had been founded in 1929 already, Europe started with national Acoustical societies soon after world-war II. The first attempt to combine forces in a supranational umbrella organization had led to the foundation of FASE (Federation of Acoustical Societies of Europe) in 1972 which later (1993) was replaced by the European Acoustics Association (EAA). 

As can be seen from the contributions to the special session at Forum Acusticum 2023 [8], many of these societies were founded by and around noise control intentions and initiatives, frequently starting from building and architectural acoustic requirements.  

But the discipline of noise control was self-confident enough to build up its own supranational organization. After the stormy formative years of the 1950s and 60s, the 70s brought a first return to the values of environment and sustainability. In Germany, this was to be seen by environmental legislation and important regulatory initiatives. In the US, this political spirit was driving new national noise control initiatives by the Federal Government, thus picking up and contributing to the so-called “environmental decade”. 

This, the spirit of that time, gave the background for a historic initiative aiming for two things: 

• to establish and strengthen the discipline and the profession of noise control engineering and to 

• implement and maintain a continuous platform for scientific exchange of views, experiences and ideas in all areas of noise and noise control. 

The first was done in 1972 by founding INCE/USA, the Institute of Noise Control Engineering of the United States of America, the second by running an experimental conference, Inter-Noise 1972, in Washington DC. This experiment turned out to be such a success that it immediately was followed up by a second one, 1973 in Copenhagen, and a third one, 1974 in the US again. The experiment by itself had been able to turn to a most promising reality, to the ongoing series of international noise control conferences, the Inter-Noise series! 

It was this international character of the series then which – in turn – required an international body running and supporting it in a responsible way. And it was just logical then to define and establish such an appropriate executive body, the International Institute of Noise Control Engineering, I-INCE. This was decided at another conference, the International Congress on Acoustics, ICA, being held in London in summer 1974. It then was announced on September 30, 1974, at the third Inter-Noise conference in Washington, D.C., and it was formally established the day after, on October first, in Zurich, Switzerland, as a non-profit association according to Swiss civil law. A more detailed review of the early years of Inter-Noise and I-INCE can be found in [14]. 

Today, exactly fifty years after its foundation, I-INCE is a strong community of 37 member societies from 35 countries and its series of Inter-Noise congresses has become the obvious, well established “must” meeting point for the large community of noise control engineers and all being interested in the field. 

Summary and Conclusion 

Fast reconstruction after World War II and upcoming comfort requirements from the following economic miracle rapidly increased the demand for technical acoustic know-how. Lacking any proven engineering tradition before, the involvement of technical acoustics relied on both, new and practicable research results as well as consulting services of specialized, practically experienced acoustic engineers who soon were able to establish themselves as a crucial interdisciplinary discipline. Then, growing comfort-of-life demands, together with increasingly urgent requirements of preservation of our environment, further forced acoustics and acousticians to control sounds. Thus, driven by social demands and driving for new results of scientific research and development, application-oriented engineering acoustics was closely bound into the iterative cycle which made acoustics a relevant and exciting discipline again, thus essentially contributing to its renaissance in the second half of the 20^th century. 

Acknowledgements 

The author gratefully acknowledges and thanks all contributors to the session “Activities in Acoustics of European Research Centers and Companies during the 20th Century” being held at Forum Acusticum 2023 in Torino, Italy. The wide variety of their contributions provides and preserves a high value heritage for later access, findings and extensions. It would be highly recommendable and worthwhile also to ensure comparable material collections for the history of noise control and noise control engineering. 

Illustrations 

The author equally thanks all persons and institutions involved for their kind provision of photos: the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig and Berlin, the Institute of Technical Acoustics (ITA) in Berlin, the Technical University in Dresden, the engineering consultancy Müller-BBM in Planegg (Germany) as well as Rolf Dietzel, Joachim Feldmann, Dieter Guicking and Michael Möser. 

References 

1. R.T. Beyer. Sound of our Times, Springer, New York, 1999. 

2. H. v. Helmholtz. On the Sensations of Tone, 3rd Edition, Cambridge University Press, 2009. 

3. Lord Rayleigh. Theory of Sound, 2 volumes, reprint of 2nd Edition, Dover Publications, New York, 1945. 

4. R. Courant and D. Hilbert. Methods of Mathematical Physics I & II, Wiley, 1989. 

5. J. Scheuren. 100 Years of Noise Control Engineering in Germany (in German). Zeitschrift für Lärmbekämpfung (ZfL), 49(6), pp 199-218, Springer-VDI, Düsseldorf, 2002. 

6. J. Scheuren. The consolidation of Engineering Acoustics as an example of contextual history of science. Proc. of the 23^rd International Congress on Acoustics (ICA), pp 7002-7006, Aachen, 2019. 

7. J. Scheuren. Stages in the development of Acoustics in Germany (in German). Akustik Journal 03/24, Deutsche Gesellschaft für Akustik e.V. (DEGA), Berlin, 2024. 

8. Activities in Acoustics of European Research Centers and Companies during the 20th Century. 
   Structured Session at Forum Acusticum 2023 (organized by J. Scheuren and A. Dobrucki).  
   In Proceedings of FORUM ACUSTICUM 2023, Torino, Italy, September 2023. 
   also to be published separately as an electronic booklet. 

9. J. Scheuren and M. Moeser. The Institute of Technical Acoustics at the Technical University of Berlin – a foundation at the right time and place. In Proceedings of FORUM ACUSTICUM 2023, Torino, Italy, September 2023. 

10. W. Kropp, K. Larsson and P. Thorssen. Building Acoustics and the “Million Programme” in Sweden. In Proceedings of FORUM ACUSTICUM 2023, Torino, Italy, September 2023. 

11. L. Beranek. Riding the waves – a life in sound, science and industry. MIT -Press, Cambridge Mass., 2008. 

12. J. Scheuren. Turning and providing Acoustics to engineering practice – foundation and early development of Müller-BBM in Germany. In Proceedings of FORUM ACUSTICUM 2023, Torino, Italy, September 2023. 

13. R. Mettin and W. Lauterborn. Acoustics in Göttingen: Research at the Drittes Physikalisches Institut during the 20^th Century (and beyond). In Proceedings of FORUM ACUSTICUM 2023, Torino, Italy, September 2023. 

14. W.W. Lang. A quarter century of noise control – a historical perspective. Acoustics Bulletin (IOA), 21(4), pp 5–10, 1996.