9
Education Supply and Industry Demand for Noise Control Specialists

The Massachusetts Institute of Technology (MIT) was an early leader in noise control education. Courses in acoustics and acoustical engineering were taught there in the 1950s and 1960s, and a series of summer courses were offered. “Noise Control Engineering Design,” believed to be the first undergraduate course with “noise control engineering” in the title, was taught by Professor Conrad Hemond at the University of Hartford beginning in 1971. Another course at the same university, “Engineering Acoustics,” has been taught since the 1960s and is still a prerequisite for the noise control engineering course, a full-semester project course. Purdue University and others began to offer undergraduate courses in noise control in the 1970s, soon after enactment of the Noise Control Act of 1972.

The first graduate course with “noise control engineering” in the title is believed to have been taught in the early 1970s by Professor Uno Ingard in the MIT Department of Aeronautics and Astronautics. Today graduate programs have been established—for example, in the mechanical engineering department at Purdue University and in the Graduate Program in Acoustics at Pennsylvania State University (Penn State), which offers master of engineering/master of science and doctoral degrees in the field of acoustics.

UNDERGRADUATE EDUCATION IN NOISE CONTROL ENGINEERING

Most existing noise control and acoustics courses are taught either at the graduate level or are noncredit short courses. The committee believes that academic institutions should find room in their curricula to offer an undergraduate course in noise control engineering that could provide a basic knowledge and understanding of noise control. The course could be offered as an elective in a bachelor’s degree program or as a course for a minor (e.g., in acoustics or interdisciplinary studies). Academic institutions could also offer capstone project courses, undergraduate research courses, honors projects, technical or free electives, and so on.

Objectives for Undergraduate Courses

Learning objectives for one (or more) undergraduate course(s) in the science and practice of noise control engineering course are offered below:


Objective 1: Understand how noise is measured, using decibels and frequency weighting, how to describe sound in frequency bands, and how to apply international and national standards.

1.1

Learn how to measure sound pressure level in decibels (dB) using the sound-level meter and the A and C frequency weighting scales.

1.2

Learn to describe sound levels in frequency bands (e.g., narrow and octave/one-third octave bands).

1.3

Understand the mechanisms of human hearing and the effects of noise on people, including noise-induced hearing loss, annoyance, perceived noisiness, speech interference, enjoyment of music, etc.

1.4

Learn to apply criteria for controlling noise and vibration in communities, buildings, vehicles, and industrial machines, based on international or national standards and recommended practices.

1.5

Examine at least one case study that shows how these principles can be used in a real-world situation.

Objective 2: Understand the nature of sound fields, noise sources, and noise control paradigms.

2.1

Learn the concepts of noise source, path, and receiver and how to use them to define a real-world problem.

2.2

Learn the basic description of sound waves, including one-dimensional plane waves and spherical waves, near- and far-field characteristics, anechoic chamber free-field concepts, and diffuse field concepts in reverberant rooms.

2.3

Understand relationships between vibration and



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9 Education Supply and Industry Demand for Noise Control Specialists Objectives for undergraduate Courses The Massachusetts Institute of Technology (MIT) was an early leader in noise control education. Courses in acoustics Learning objectives for one (or more) undergraduate and acoustical engineering were taught there in the 1950s course(s) in the science and practice of noise control engi- and 1960s, and a series of summer courses were offered. neering course are offered below: “Noise Control Engineering Design,” believed to be the first undergraduate course with “noise control engineering” Objectie : Understand how noise is measured, using in the title, was taught by Professor Conrad Hemond at the decibels and frequency weighting, how to describe sound University of Hartford beginning in 1971. Another course in frequency bands, and how to apply international and at the same university, “Engineering Acoustics,” has been national standards. taught since the 1960s and is still a prerequisite for the noise 1.1 Learn how to measure sound pressure level in deci- control engineering course, a full-semester project course. bels (dB) using the sound-level meter and the A and Purdue University and others began to offer undergraduate C frequency weighting scales. courses in noise control in the 1970s, soon after enactment 1.2 Learn to describe sound levels in frequency bands of the Noise Control Act of 1972. (e.g., narrow and octave/one-third octave bands). The first graduate course with “noise control engineer- 1.3 Understand the mechanisms of human hearing ing” in the title is believed to have been taught in the early a nd the effects of noise on people, including 1970s by Professor Uno Ingard in the MIT Department of noise-induced hearing loss, annoyance, perceived Aeronautics and Astronautics. Today graduate programs noisiness, speech interference, enjoyment of music, have been established—for example, in the mechanical engi- etc. neering department at Purdue University and in the Graduate 1.4 Learn to apply criteria for controlling noise and Program in Acoustics at Pennsylvania State University (Penn vibration in communities, buildings, vehicles, and State), which offers master of engineering/master of science industrial machines, based on international or na- and doctoral degrees in the field of acoustics. tional standards and recommended practices. 1.5 Examine at least one case study that shows how these uNDERgRADuATE EDuCATION IN NOISE CONTROL principles can be used in a real-world situation. ENgINEERINg Objectie : Understand the nature of sound fields, noise Most existing noise control and acoustics courses are sources, and noise control paradigms. taught either at the graduate level or are noncredit short 2.1 Learn the concepts of noise source, path, and re- courses. The committee believes that academic institutions ceiver and how to use them to define a real-world should find room in their curricula to offer an undergradu- problem. ate course in noise control engineering that could provide 2.2 Learn the basic description of sound waves, includ- a basic knowledge and understanding of noise control. The ing one-dimensional plane waves and spherical course could be offered as an elective in a bachelor’s degree waves, near- and far-field characteristics, anechoic program or as a course for a minor (e.g., in acoustics or inter- chamber free-field concepts, and diffuse field con- disciplinary studies). Academic institutions could also offer cepts in reverberant rooms. capstone project courses, undergraduate research courses, 2.3 Understand relationships between vibration and honors projects, technical or free electives, and so on. 

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 TECHNOLOGY FOR A QUIETER AMERICA radiated noise in terms of sound power, radiation simple noise and vibration control devices) should be used efficiency, and surface velocity. to engage students. Guest speakers from industry, the com- 2.4 Understand the basic noise sources (e.g., mechani- munity, and other academic departments could be brought in cal, airflow, electro-mechanical) and relationships to illustrate the fascinating and challenging aspects of noise between operational parameters and noise. control engineering. 2.5 Learn to evaluate common noise sources in build- ings, communities, industry, and vehicles and par- undergraduate Course Descriptions ticipate in an exercise in setting a noise target for at least one source. A short description of an undergraduate course that meets 2.6 Examine a case study that shows how these prin- the objectives of the previous section follows. This course ciples have been applied in a real-world setting. deals with the fundamentals of noise control and engineering, including design criteria based on human response to noise (e.g., hearing damage, annoyance, speech intelligibility, en- Objectie : Learn how to control structureborne, airborne, and fluidborne noise paths. joyment of music). Acoustic wave propagation and transmis- 3.1 Understand the parameters of a mechanical oscil- sion phenomena are covered, along with noise measurement lator, including natural frequency and damping and reduction techniques. Applications deal with machines, ratio. building design, musical instruments, and speakers. Ideal 3.2 Learn the concept of vibration isolation and how to acoustical rooms (e.g., anechoic and reverberant rooms) specify the stiffness of a system. are demonstrated. Students are expected to conduct sound 3.3 Learn the concept of resonance control and how to measurements on a source of their choice using a handheld specify viscous or structural damping. sound-level meter. 3.4 Understand the concepts of absorption and reflec- Another example of a course that meets the objectives tion of harmonic sound waves by solid and fluid is “Noise Control in Machinery” taught at Penn State. The boundaries and materials and be able to relate them course covers the nature of noise sources in machine ele- to the impedances of materials or duct elements ments and systems and deals with the propagation and reduc- (including reactive and resistive characteristics). tion of machinery noise and the effects of noise on people. 3.5 Understand the concept of sound transmission through a wall and the mass law. gRADuATE EDuCATION IN NOISE CONTROL 3.6 Learn the characteristics of sound-absorptive mate- ENgINEERINg rials and how to specify their performance. 3.7 Learn the concepts of basic muffler elements, such On the graduate level, institutions have offered several as expansion chambers and side branch resonators, engineering-science-based courses, such as engineering and how to specify their performance. acoustics, aero-acoustics, continuous vibrations, and digital 3.8 Learn how to design a simple enclosure and how to signal processing. However, a comprehensive search of control noise in various ways. graduate programs turned up only a few courses with “noise 3.9 Examine a real-life problem that illustrates how control” in the titles. Penn State and Ohio State offer a se- these principles have been applied and propose quence of year-long graduate courses, and the University source or path noise control solution(s). of Nebraska at Lincoln offers one graduate-level course. 3.10 Critically examine professional issues, such as Catalog descriptions are listed below: safety, ethics, economics, product liability, and environmental concerns via case studies and group • Penn State, Noise Control Engineering I: The first of discussions. three courses, this course provides an orientation to the program and covers fundamentals of noise control. The objectives described above should be considered minimal requirements for a one-semester course. Issues • Penn State, Noise Control Engineering II: This course related to prerequisites and materials would depend on the applies fundamentals of noise control covered in Noise program offering the course, the educational level of the Control Engineering I to noise generation, propaga- student, and other specific factors. Evaluation methods (as tion, measurement, and effects. appropriate) include homework assignments and examina- • Penn State, Noise Control Engineering III: This course tions, classroom discussion, and student-conducted noise covers advanced methods for analyses of noise and measurements on simple noise sources. Instructors are en- vibration and treatments for control of noise and vibra- couraged to use modern pedagogical methods (e.g., sound tion. visualization codes, field animation software, MATLAB (or comparable codes), Internet-based tools). Experimental • Ohio State, Automotive Noise, Vibration, and Harsh- demonstrations (on the nature of sources and/or the effect of ness Control I: An integrated study of acoustics, shock

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 EDUCATION SUPPLY AND INDUSTRY DEMAND FOR NOISE CONTROL SPECIALISTS and vibration, and dynamic design issues with empha- applicable to fluid and structural sources and paths. sis on automotive case studies and problem-solving • Topics for case studies and guest lecturers include the methodology. development of experimental facilities, structureborne noise paths in products, muffler system tuning, statisti- • Ohio State, Automotive Noise, Vibration, and Harsh- cal energy analysis applied to interior acoustics, inter- ness Control II: Continuation of 777 with focus on national design and marketing (from the noise control source-path-receiver identification, modal analysis, perspective), ethics, and professionalism. passive/active control, and machinery diagnostics. • Ohio State, Automotive Noise, Vibration, and Harsh- The following course description is based on Penn State’s ness Control III: Continuation of 778 with focus on Noise Control Engineering III: advanced modeling and experimental methods, struc- tural/acoustic interactions, and flow-induced noise and • Sources of noise: power transmission, electric equip- vibration. ment, nonturbomachinery, flow-induced, and turboma- chinery. • University of Nebraska at Lincoln, Advanced Noise • Outdoor noise and structural acoustics: outdoor noise Control: Characterization of acoustic sources, use and propagation, transportation noise, response of propa- measurement of sound power and intensity, sound- gation in and radiation from structures, coupled struc- structure interaction, acoustic enclosures and barriers, tures. muffling devices, vibration control, and active noise • Measurement and analysis: single- and two-channel control. frequency analyses, coherence, and transfer func - tions. The graduate-level sequence in automotive noise, vibra- • Noise treatments: vibration mounting systems, damp- tion, and harshness control at Ohio State was developed by ing treatments, mufflers and silencers, active noise, and the university and General Motors in the mid-1990s. The vibration control. three engineering practice courses are based on an innova- • Modeling: finite and boundary element methods, sta- tive case study approach (similar to the approach used in tistical energy analysis. business, law, and medical schools). This course sequence teaches the integration of concepts of mechanical vibrations, Faculty should consider offering noise control courses acoustics, digital signal processing, and machinery dynam- that provide a balance between theory and engineering ics. Overall, the concepts of noise control are related to practice without sacrificing academic rigor. Classroom edu- product design, manufacturing, materials, performance, and cation can be augmented by field trips, guest lectures, and economic considerations. seminars. Industry, government laboratories, and consulting firms could provide valuable help by offering their facilities Sample Course Descriptions for course-related experiments or miniprojects. A graduate internship program would motivate students while building Traditionally, topics and coverage in a graduate-level a cadre of future noise control engineers. course tend to depend on the research expertise of the instruc- tor, students’ backgrounds, and the needs of ongoing research CONTINuINg EDuCATION AND SKILL DEVELOPMENT programs. The characteristics of a sample course in noise and vibration control (with the emphasis on engineering practice) Distance Education listed below are based on the third course at Ohio State. Changes in products, competitive features, and regula- • Wave equation solutions: Three-dimensional acoustic tions continue to create a need for expertise in noise control cavities and basic sources, such as monopole and di- engineering. Companies and agencies often fill these needs pole. by calling on employees who know the business well and • Noise source identification: acoustic intensity using can assume these responsibilities in addition to or in lieu of the two-microphone method, near-field holography, their regular jobs. Because of a paucity of formally trained structural-acoustic responses using modal expansion, noise control engineers in most companies, these emerging operating motion surveys, and laser scanning system. requirements are often assigned to engineers with training • Noise and vibration sources: (1) friction sources, such in fields that may overlap with noise control engineering as brake squeal, belt vibration, and tire noise; (2) clear- (e.g., aerodynamics, crash-worthiness, physics, mechani- ance sources, such as transmission rattle, door slam, cal engineering, vibrations, or electrical engineering) or to and piston slap; (3) aerodynamic sources, such as individuals with no previous experience with noise control vehicle components, alternators, and antennas engineering who are judged to have outstanding skill in other • Passive and active noise and vibration control methods areas (e.g., product design). These new “noise control prac-

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4 TECHNOLOGY FOR A QUIETER AMERICA titioners” often need opportunities for professional develop- are generally intensive but offer little hands-on experience ment outside of formal educational settings. In fact, there are and no competency tests. University offerings tend to be many venues for professional development, such as distance adapted versions of coursework for which a need has been education through universities, short-course offerings from identified. universities or private sources, and conferences. Short courses can be divided into two groups: (1) general Distance education offerings are often modified ver- courses that teach fundamental topics and (2) advanced sions of university courses. Ohio State, Penn State, and courses specific to an emerging area of interest. General Purdue University offer courses via video link and over the courses tend to serve the same audience as distance educa- Internet. tion courses, usually individuals who do not have access to Ohio State offers a one-year sequence of three quarter- distance education or who think a short course meets their long courses developed as a noise and vibration control en- needs in terms of logistics or learning methodology. Stu- gineering sequence for General Motors. The sequence is of- dents in advanced courses tend to be well educated in the fered in the distance learning mode (via asynchronous video fundamentals of noise control engineering but need to learn recordings and synchronous webex/video conferences). In about emerging or advanced topics. However, students in addition, the sequence is offered biennially to approximately an advanced course often have different backgrounds and 15 to 30 students at General Motors and 15 to 25 graduate different levels of understanding, which make teaching such students at Ohio State. courses a challenging undertaking. Examples of advanced In the past, Penn State offered a three-course sequence in short courses include topics in signal processing, active noise the fundamentals of acoustics and noise control, but it was control techniques, and nonlinear vibrations. discontinued when the developer and instructor of the course Short courses offered by private sources include both retired. The sequence was offered asynchronously (at each general and advanced topics. Many of these courses were de- student’s preferred pace) through Internet and video record - veloped to address common recurrent or customer problems ings. Total enrollment was approximately 100. However, or to educate potential customers who might use the services Penn State continues to offer many courses through distance offered by the sponsoring company. A few courses are used education that are fundamental to noise control engineering: as marketing tools to attract business or create new opportu- Fundamentals of Acoustics, Digital Signal Processing, Elec- nities for the company. For example, a one-day course on the troacoustic Transducers, Acoustics in Fluid Media, Acousti- basics of acoustic measurement might be a demonstration of cal Data Measurement and Analysis, Techniques for Solv- a new acoustical measurement device. ing Acoustic Field Problems, Sound/Structure Interaction, A large proportion of continuing education in noise Flow-Induced Noise, Audio Engineering, Sound Quality, control engineering is provided by private sources. Short Computational Acoustics, and Nonlinear Acoustics. More courses, whether offered by universities or private compa- than 70 students enroll in these courses each semester. Upon nies, often attract students with diverse backgrounds, cover successful completion of 30 credits, a student is awarded a materials as quickly as possible with maximum possible master of engineering degree in acoustics. retention, and motivate participants to learn subjects that Purdue offers five courses in acoustics and vibrations, may not have been of immediate interest. through the IHETS interactive video network and by vid- eotape, to several companies that have contracted courses Technical Conferences through the university. Courses are offered on a two- or four- year cycle, depending on their popularity. Approximately 20 Technical conferences are widely used as educational students take these courses each year. vehicles, perhaps more in noise control engineering than All of these distance-learning courses, which are slightly in other fields. About 1,400 people attend the biennial SAE modified versions of courses offered on campus in formal (Society of Automotive Engineers) International Noise and noise control engineering or acoustics programs, include Vibration Conference and Exhibition, which generally has homework and test requirements. Students may sign up for fewer than 300, mostly practical, presentations. The educa- a graduate degree program through distance education with tional mission of the conference is described in the brochure these courses as part of a plan of study or they may take for the 2009 event (http://www.sae.org/eents/nc/): them on a nondegree status as courses of interest. In either case, the courses are rigorous and provide a strong gen- The SAE Noise and Vibration Conference and Exhibition— eral background in acoustics, vibrations, and noise control the only dedicated mobility noise, vibration and harshness engineering. event in North America—will bring together nearly 1,400 leading experts and specialists from all points of the globe to learn about, present and display the latest technological Short Courses innovations all under one roof. Attendees will gain a full understanding of NVH and sound quality issues related to Short courses are available from universities and private vehicle design, engineering and testing, learn the latest trends sources. Courses run from a single day to one week and

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 EDUCATION SUPPLY AND INDUSTRY DEMAND FOR NOISE CONTROL SPECIALISTS faculty members with training in noise control engineer- and solutions during the technical paper presentations, visit innovative organizations at the exhibition, and exchange ing. The database of the Acoustical Society of America ideas with industry peers from around the world during spe- (ASA) identifies universities that offer programs in various cial networking opportunities. This is a must-attend eent! subdisciplines of acoustics.1 A search for “noise and noise control” reveals that of the 39 universities identified, only The event includes approximately a dozen affiliated short eight have more than two faculty members in the area of courses, as well as workshops, demonstrations, and a large noise control engineering. Although these individuals may exhibition of products and materials. be well respected in the field, it is difficult for students in Technical conferences sponsored by the Institute of Noise those programs to receive the same level of education as they Control Engineering (NOISE-CON and INTER-NOISE), the would in a larger program. National Research Council Transportation Research Board Noise control engineering programs are also housed in a (summer meeting of the Transportation Noise Committee), variety of departments. According to the ASA database, the and the American Institute of Aeronautics and Astronautics majority are housed in mechanical engineering or aerospace (Aeroacoustics Conference) place less emphasis than SAE engineering departments. However, the others can be found on learning and more on technical exchanges by technical in departments of electrical engineering, physics, civil engi- leaders. However, practitioners who want to learn something neering, oceanography, architecture, communication science attend all of the conferences; all of them offer short courses and disorders, recording arts and sciences, speech pathol- in conjunction with the event. ogy, and audiology, and other unlikely departments, such as agriculture, otolaryngology, and biomaterials. Figure 9-1 shows the percentages of faculty members associated with Conclusion departments identified as offering noise control engineering Because the demand for noise control engineers is much programs. g reater than the supply of formally trained engineers, distance education and continuing education play a large Lack of Homogeneity role in developing practitioners in the field. The strongest offerings play a valuable role and should be encouraged to The lack of homogeneity reflects the multidisciplinary continue. However, many offerings compromise quality for nature of noise control engineering, which creates some expediency or marketability. Nevertheless, both will con- benefits but also several challenges. The benefit is in bring- tinue to be important for the foreseeable future. Therefore, ing people from different backgrounds into the field who can guidelines associated with a certification process for noise contribute valuable new perspectives. One of the major chal- control engineering in continuing education programs would lenges is that there is no consistent “home” for the discipline help participants gauge the content and value of courses and on university campuses. other offerings. In the middle of the twentieth century, most noise control engineering programs were housed in physics departments; a smaller number were housed in engineering departments— SuPPLy-SIDE CHALLENgES primarily mechanical and electrical engineering. Today most A major challenge to an adequate supply of well-trained are housed in mechanical engineering departments, although, noise control engineers is that educational programs are as indicated above, many other departments are involved in n ot homogeneous. For “mainstream” engineering dis - noise control engineering education. This lack of a focal ciplines, organizations such as ABET (http://www.abet. point can make it difficult for employers or anyone else look- org/requirements) dictate that a majority of engineering ing for help in the area of noise control engineering to know departments at universities across the nation offer similar exactly what to look for—a mechanical engineer, a physicist, courses and cover the same general content. However, there an electrical engineer, or someone else. are no such requirements for noise control engineering. A Another challenge is that people trained in different en- number of university departments offer education in noise gineering and scientific disciplines tend to look at problems control engineering either as degree programs, continuing or from different perspectives and use different terminologies, distance education, or both. However, even though they may each of which has advantages and disadvantages. The three sound alike, these departments often look very different. In main (complementary) perspectives are: comparing university departments, two characteristics vary dramatically—the size of the department and the school or discipline in which the department is housed. 1This database is cited because it may be less biased to a given discipline Departments that have attained a critical mass of faculty than some other databases. For example, the American Society of Mechani- cal Engineers (ASME) may be biased toward mechanical engineers, the members trained in noise control engineering often offer American Institute of Aeronautics and Astronautics (AIAA) may be biased substantial courses and research opportunities. However, toward aerospace engineering, and the Institute of Electrical and Electronics a large number of other departments have only one or two Engineers (IEEE) may be biased toward electrical engineers.

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6 TECHNOLOGY FOR A QUIETER AMERICA Other 15% Speech Pathology 2% Ocean Engineering 3 % Mechanical Architectural Engineering 3 % Engineering 43 % Communication Science 4% Civil Engineering 2% Electrical Engineering 6% Physics 6% Aerospace Engineering 16 % FIGURE 9-1 U.S. noise control programs in university departments. Source: Reprinted with permission from Scott D. Sommerfeldt, Brigham Young University. Figure_9-1.eps • analysis in terms of acoustic or structural modes Each application area in noise control engineering tends • analysis in terms of wave propagation to have several metrics that are particularly useful for that • analysis in terms of sound levels and noise metrics application. This raises two potential difficulties. First, some people who work in noise control engineering were never Many noise control applications are typically analyzed in taught the concept of sound levels and may be uncomfort- terms of acoustic or structural modes. This approach is use- able using metrics. Second, many who have been exposed ful for analyzing finite structures or enclosed sound fields, to basic metrics like sound pressure level are unfamiliar, and and considering a problem in terms of the modal response hence uncomfortable, with metrics used in other application of a system can yield considerable insight. This approach areas. In either case, additional training in metrics (both could address problems in the sound field in rooms, auto- definitions and how they are used to characterize noise) mobiles, aircraft, and equipment enclosures, or the vibra- would be beneficial. tion response of equipment, transformers, housings, and so These three complementary, intertwined descriptions of forth. The modal approach can also be useful for analyzing noise control analysis can create an obvious problem. People sound/structure interactions (i.e., when there is significant with different educational backgrounds may have been ex- coupling of a vibrating structure and the fluid into which the posed to only one or perhaps two of these approaches (e.g., structure radiates). modes and sound levels) but not the third approach (metrics). However, a modal approach is not effective for addressing Even if they have been exposed to all three, the quality of acoustical problems in large areas, such as community noise. education can vary dramatically. The problem is more pro- For these and other applications a wave propagation approach nounced at institutions that do not have large programs where is typically used. Wave propagation analysis is applicable to there are not enough resources for students to be exposed to community noise problems involving source radiation and the full range of approaches. This problem is also common sound propagation, reflection/transmission problems, acous- for individuals not trained in acoustics and noise control tical properties of porous materials, sound propagation in who were assigned to work on noise control applications by heating and ventilation systems, and mufflers. their employers. In most cases they are familiar with only Over the years, noise control terminology using frequency one approach and must somehow make up that deficiency averaging and other attempts to account for human percep- to be effective. Thus, they must have access to educational tions of sound have been developed to support an engineer- opportunities, and they must take advantage of them. ing approach to noise control. A substantial portion of noise The multidisciplinary nature of noise control engineering control engineering involves the use of metrics based on also contributes to challenges for industry employers, who sound levels (expressed in decibels). may expect new employees to understand sound propagation,

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7 EDUCATION SUPPLY AND INDUSTRY DEMAND FOR NOISE CONTROL SPECIALISTS acoustic and structural absorption, reflection/transmission after most decisions have been made. Component suppliers phenomena, instrumentation and measurement techniques, often do not have any staff or laboratories for noise control basic data and signal processing, computational techniques, design and therefore depend heavily on consultants. Thus, and some basic psychoacoustics. unnecessary noise problems arise, especially for fans, mo- To address the challenges just described, it would be tors, transmissions, and pumps. helpful for noise control engineering educators to establish a standard core curriculum for noise control engineering pro- Aircraft Companies grams. Specialized coursework would also be desirable, but a standard curriculum would at least ensure that fundamental Aircraft companies are concerned with reducing both core concepts are understood by all students trained in the interior and exterior aviation noise. Because weight is an field. However, given the variety of departments that house important factor in the design of airplanes, the interior of an noise control engineering programs, a standard curriculum airplane is highly susceptible to both airborne and structure- is not likely to be adopted, unless an external body, such as borne engine noise and wind-rush noise caused by airflow ABET, pushes to implement a standard core curriculum. over the fuselage. Thus, noise controls must be lightweight and highly efficient. Noise control engineering for aircraft must begin at the DEMAND FROM INDuSTRy conceptual design phase and continue through the develop- Low-noise levels are becoming increasingly important for ment of the detailed design and prototype. Airframe compa- many products. In the cabin of vehicles, for example, low nies such as Boeing hire aggressively and have noise control noise is strongly associated with high quality, as evidenced engineering personnel throughout the company. Boeing by the number of automobile commercials for high-end prod- also invests intensively in continuing education to ensure ucts that emphasize noise reduction features designed into that engineering designers in general are sensitive to noise the vehicle. The low-noise characteristics of appliances are reduction methodologies. also emphasized in sales literature and advertisements. We Exterior aircraft noise has received considerable attention. increasingly hear about public resistance to airport expan- Policy has dictated a 10 dB per decade reduction in aircraft sion or construction based on environmental noise. Similar noise and mandated the retirement of a major portion of the resistance has been raised to expansion or construction of fleet. Cost estimates for achieving this goal are as high as $5 highways. Occupational environments are also concerned billion. The noise control engineers who carried this effort about workers’ exposure to noise. Considering the growing forward were employed by aircraft engine manufacturers and interest in noise control in all of these areas, the demand for the National Aeronautics and Space Administration. noise control engineers in all fields will also grow. As aircraft engines have become quieter, attention has turned to reducing noise from the airframe itself. Thus. today airframe manufacturers are more involved in exterior noise Automobile Companies control than they were in the past. Most of the noise control Automakers compete on the basis of cost, perceived engineers involved in current studies have advanced degrees quality, safety, and fuel mileage. Noise reduction has been in acoustics with expertise in aerodynamics. closely associated with high quality, as has been apparent in television and print advertising over the past decade. Auto- Noise Reduction in Other Areas mobile companies have even become interested in tuning the noise of vehicles for so-called sound quality. Traditionally, Purchasers of appliances also associate quiet with quality. the top 10 warranty issues include troublesome noises and Companies that plan to market their products internationally vibrations, such as squeaks and rattles. In addition, reducing where buyers live in densely populated settings must provide noise overall usually meant adding weight to the vehicle, quiet appliances to meet market regulations. Many appliance which reduced fuel mileage. manufacturers have built small noise control laboratories, Thus, noise control engineering is a significant aspect but they do not have critical mass to retain noise control of all parts of automobile design, from the conceptual phase engineers in a market in which demand greatly exceeds the when targets are set and basic architecture is decided to the supply. finishing touches. In fact, engineers are needed at all levels In defense applications, noise control is not as uniformly and in all operations of companies, ranging from noise important as it is in the commercial sector—with a few no- control specialists capable of setting targets and diagnosing table exceptions. During the cold war, acoustical detection problems to noise-aware designers capable of incorporating of submarines and the suppression of the acoustical signa - noise control strategies into routine design decisions. ture of submarines were high-priority technologies. During Currently, many automotive companies have only enough those years, very large numbers of noise control engineers, noise control engineers to staff central noise control labora- consultants, and contractors were employed in defense agen- tories. The staff operates in a reactive mode to fix problems cies. Noise reduction is still a significant aspect of stealth

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8 TECHNOLOGY FOR A QUIETER AMERICA weapons systems for air, ground, and naval applications, and engineering generally report that inquiries about graduates noise control engineering is widely used in all branches of qualified in noise control engineering and related disciplines defense. The U.S. Department of Defense (DOD) has shown exceed the local supply. Another indication of an imbalance significant interest in personnel who can assist with hearing between supply and demand comes from educators, who protection and other occupational safety issues. Some of the report that salary offers for new graduates with backgrounds largest veterans’ benefits payouts are for hearing loss suffered in noise control are higher than for other engineers and that by DOD personnel. these students often receive multiple offers. The consensus at both workshops was that graduate programs in noise control engineering should be expanded Consulting Companies and that funding for current educational programs should be Based on membership in the National Council of Acous- increased to ensure a steady supply of young professionals tical Consultants, it is estimated that approximately 2,000 entering the field. In addition, undergraduate studies in noise noise control and acoustical consultants are practicing in the control engineering should be expanded to ensure the avail- United States, and the number continues to grow. Consulting ability of workers who can perform engineering tasks, such companies occupy a unique position between the public and as making measurements and design calculations at the basic either government or commercial operations. Effective noise engineering levels. This would not only answer a need of em- control engineering consultants must not only understand ployers but would also free practicing engineers (generally the fundamentals of the field, but must also have the skills trained in other disciplines) who have difficulty with some to understand policy and interact with a variety of clients, approaches to noise control that are counterintuitive. including real estate developers, construction companies, For American industries to produce quieter, more com- hospitals, municipal governments, and others. The situation petitive products for domestic and global markets, noise was aptly described in a private communication to the com- emission and associated issues (such as costs, environmental mittee by Senior Vice President Nicholas Miller of Harris considerations, and system design issues) must be added Miller Miller & Hanson, Inc., a leading consulting company to the list of product and equipment requirements. This in transportation noise: will mean that design and manufacturing engineers must understand some elements of noise control engineering and Since there seems to be very little education at the under- closely related engineering disciplines. There is also a need graduate level in noise control or acoustics, we do not expect for qualified personnel in government for policy develop- to find people with undergraduate degrees with knowledge ment and enforcement. of acoustics. On the other hand, by the time they have done a serious MS or PhD in acoustics, they are likely overquali- fied for the positions we need. We often hire people with FINDINgS AND RECOMMENDATIONS little or no knowledge of noise and acoustics and train them internally for the skills we need. Widespread undergraduate Undergraduate education in noise engineering varies exposure to the basics of noise and acoustics would help us greatly from institution to institution in terms of the depart- identify and retain good staff. ment in which it is housed and the courses offered. Funding for noise control engineering programs at universities is problematic, and support for graduate students to assist in DOES DEMAND EXCEED SuPPLy? research (or teaching) and to develop a new cadre of profes- The answer to the question of whether demand exceeds sionals is inadequate. The geographic distribution of leading supply is based on responses collected during a workshop programs is also a concern. The largest programs tend to be held in Reno in October 2007 as part of the NOISE-CON where funds for sponsored research are available rather than 2007 Conference and on other sources. This issue was also where industry demand for specialists is highest. a subject of discussion at a National Academy of Engineer- Recent reports highlighting the state of engineering edu- ing noise control research workshop in June 2008. Both cation in the United States, such as The Engineer of 00: Vi- workshops and an informal survey of engineers working in sions of Engineering in the New Century (NAE, 2004), which the field indicate that there is a strong demand for graduates offers “future scenarios of the possible world conditions in noise control engineering. for the 2020 engineer,” recommend changes in engineering The same results were found in a poll of key academics in curricula and pedagogical methods. The report recommends U.S. institutions who say they regularly receive phone calls that practical and interdisciplinary issues that impact soci- and e-mail asking about graduate students with skills in noise ety and industry, such as ethics, safety, and environment, control engineering. The number of practicing engineers in should be integrated into the undergraduate engineering cur- continuing education classes who have backgrounds sig- riculum. A recent report by the Carnegie Foundation for the nificantly outside noise control engineering also indicates an Advancement of Teaching (Sheppard et al., 2009) finds that undersupply of well-qualified graduates. University depart- “American engineering education is too theoretical and not ments with educational opportunities related to noise control hands-on enough. . . . A widespread emphasis on theory over

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 EDUCATION SUPPLY AND INDUSTRY DEMAND FOR NOISE CONTROL SPECIALISTS practice . . . discourages many potential students while leav- A comparison of research activity on environmental noise ing graduates with too little exposure to real-world problems in Europe, Japan, and the United States clearly reveals that and ethical dilemmas.” The study committee of the present the level of activity in Europe and Japan far exceeds the report believes that the promotion of noise control engineer- level in the United States. Substantial funding for research ing in academia is consistent with the recommendations and in Europe and Japan has enabled very large scale and many visions of both reports, that it would fit the ABET criteria smaller scale studies. An indirect effect of this funding is for engineering programs, and that it would serve the needs the number of graduate students in environmental noise of related programs, such as physics, architecture, biological being educated in Europe and Japan, which has resulted in sciences, and speech and hearing. widespread understanding of acoustics and environmental The multidisciplinary nature of noise control engineering problems and helped inform decisions and encouraged poses challenges for engineering practice and for lifelong the adoption of noise mitigation efforts and appropriate learning. Typically, employees attempting to solve complex metrics. noise control problems must have a rigorous knowledge Recommendation 9-1: Academic institutions should offer of noise measurement and signal processing techniques, propagation of noise though air and structures (including an undergraduate course in noise control engineering, broad- acoustic absorption, insulation, damping, and vibration en the scope of the engineering curriculum, and increase the isolation), computational techniques, and psychoacoustics. pool of engineering graduates who are equipped to design They may also need additional expertise in specific areas of for low-noise emissions. The course could be offered as an noise control engineering (e.g., aero-acoustic problems are elective in a bachelor’s degree program or as part of a minor very different from problems raised by noise from machine (e.g., in acoustics or interdisciplinary studies). elements). Neither undergraduate nor graduate programs are Recommendation 9-2: Graduate-level noise control cours- comprehensive, and the need to understand new issues and technologies over time creates a strong demand for continu- es should provide a balance between theory and engineering ing education. practice without sacrificing academic rigor. The committee Elements of noise control engineering degree programs strongly encourages the establishment of graduate intern- should be formally taught in an intra- or interdisciplinary ships in industry and government agencies and thesis re- way by faculty in academic units (in engineering, physi- search programs to motivate students and to build a cadre cal sciences, and architecture). Major professional societ- of future noise control engineers. ies (such as AIAA, ASME, American Society of Heating, Recommendation 9-3: Federal agencies, private compa- Refrigerating, and Air-Conditioning Engineers, Institute of Noise Control Engineering of the USA, SAE). and other nies, and foundations with a stake in noise control should stakeholders should organize symposia (or special sessions provide financial support for graduate students who assist in in regular conferences), where leading academic and indus- research on, and the teaching of, noise control engineering. try leaders can propose and refine curricula and suggest im - This support is crucial for the development of noise control provements in teaching methods and delivery mechanisms. professionals and noise control educators. Collaboration among academic, research, and industry lead- ers will be necessary for the development of interesting case REFERENCES studies or practice modules that could then be disseminated NAE (National Academy of Engineering). 2004. The Engineer of 2020: to teachers of undergraduate courses. Visions of Engineering in the New Century. Washington, DC: National Funding is particularly important for research on environ- Academies Press. mental noise that encourages interdisciplinary collaboration Sheppard, S.D., W.M. Sullivan, A. Colby, K.Macatangay, and L.S. Shulman. between acousticians, engineers, social scientists, psycholo - 2009. Educating Engineers: Designing for the Future of the Field. The gists, sociologists, and health scientists to develop improved Carnegie Foundation for the Advancement of Teaching. San Francisco, CA: Jossey-Bass. metrics for evaluating the impact of noise, including annoy- ance, speech and communications interference, cognitive impairment, sleep disturbance, and health effects.

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