National Academies Press: OpenBook

Technology for a Quieter America (2010)

Chapter: 9 Education Supply and Industry Demand for Noise Control Specialists

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Suggested Citation:"9 Education Supply and Industry Demand for Noise Control Specialists." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
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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

Suggested Citation:"9 Education Supply and Industry Demand for Noise Control Specialists." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
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radiated noise in terms of sound power, radiation efficiency, and surface velocity.

2.4

Understand the basic noise sources (e.g., mechanical, airflow, electro-mechanical) and relationships between operational parameters and noise.

2.5

Learn to evaluate common noise sources in buildings, communities, industry, and vehicles and participate in an exercise in setting a noise target for at least one source.

2.6

Examine a case study that shows how these principles have been applied in a real-world setting.

Objective 3: Learn how to control structure borne, airborne, and fluid borne noise paths.

3.1

Understand the parameters of a mechanical oscillator, including natural frequency and damping ratio.

3.2

Learn the concept of vibration isolation and how to specify the stiffness of a system.

3.3

Learn the concept of resonance control and how to specify viscous or structural damping.

3.4

Understand the concepts of absorption and reflection of harmonic sound waves by solid and fluid boundaries and materials and be able to relate them to the impedances of materials or duct elements (including reactive and resistive characteristics).

3.5

Understand the concept of sound transmission through a wall and the mass law.

3.6

Learn the characteristics of sound-absorptive materials and how to specify their performance.

3.7

Learn the concepts of basic muffler elements, such as expansion chambers and side branch resonators, and how to specify their performance.

3.8

Learn how to design a simple enclosure and how to control noise in various ways.

3.9

Examine a real-life problem that illustrates how these principles have been applied and propose source or path noise control solution(s).

3.10

Critically examine professional issues, such as safety, ethics, economics, product liability, and environmental concerns via case studies and group discussions.

The objectives described above should be considered minimal requirements for a one-semester course. Issues related to prerequisites and materials would depend on the program offering the course, the educational level of the student, and other specific factors. Evaluation methods (as appropriate) include homework assignments and examinations, classroom discussion, and student-conducted noise measurements on simple noise sources. Instructors are encouraged to use modern pedagogical methods (e.g., sound visualization codes, field animation software, MATLAB (or comparable codes), Internet-based tools). Experimental demonstrations (on the nature of sources and/or the effect of simple noise and vibration control devices) should be used to engage students. Guest speakers from industry, the community, and other academic departments could be brought in to illustrate the fascinating and challenging aspects of noise control engineering.

Undergraduate Course Descriptions

A short description of an undergraduate course that meets the objectives of the previous section follows. This course 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, enjoyment of music). Acoustic wave propagation and transmission phenomena are covered, along with noise measurement and reduction techniques. Applications deal with machines, building design, musical instruments, and speakers. Ideal acoustical rooms (e.g., anechoic and reverberant rooms) are demonstrated. Students are expected to conduct sound measurements on a source of their choice using a handheld sound-level meter.

Another example of a course that meets the objectives is “Noise Control in Machinery” taught at Penn State. The course covers the nature of noise sources in machine elements and systems and deals with the propagation and reduction of machinery noise and the effects of noise on people.

GRADUATE EDUCATION IN NOISE CONTROL ENGINEERING

On the graduate level, institutions have offered several engineering-science-based courses, such as engineering acoustics, aero-acoustics, continuous vibrations, and digital signal processing. However, a comprehensive search of graduate programs turned up only a few courses with “noise control” in the titles. Penn State and Ohio State offer a sequence of year-long graduate courses, and the University of Nebraska at Lincoln offers one graduate-level course. Catalog descriptions are listed below:

  • Penn State, Noise Control Engineering I: The first of three courses, this course provides an orientation to the program and covers fundamentals of noise control.

  • Penn State, Noise Control Engineering II: This course applies fundamentals of noise control covered in Noise Control Engineering I to noise generation, propagation, measurement, and effects.

  • Penn State, Noise Control Engineering III: This course covers advanced methods for analyses of noise and vibration and treatments for control of noise and vibration.

  • Ohio State, Automotive Noise, Vibration, and Harshness Control I: An integrated study of acoustics, shock

Suggested Citation:"9 Education Supply and Industry Demand for Noise Control Specialists." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
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and vibration, and dynamic design issues with emphasis on automotive case studies and problem-solving methodology.

  • Ohio State, Automotive Noise, Vibration, and Harshness Control II: Continuation of 777 with focus on source-path-receiver identification, modal analysis, passive/active control, and machinery diagnostics.

  • Ohio State, Automotive Noise, Vibration, and Harshness Control III: Continuation of 778 with focus on advanced modeling and experimental methods, structural/acoustic interactions, and flow-induced noise and vibration.

  • University of Nebraska at Lincoln, Advanced Noise Control: Characterization of acoustic sources, use and measurement of sound power and intensity, sound-structure interaction, acoustic enclosures and barriers, muffling devices, vibration control, and active noise control.

The graduate-level sequence in automotive noise, vibration, and harshness control at Ohio State was developed by the university and General Motors in the mid-1990s. The three engineering practice courses are based on an innovative case study approach (similar to the approach used in business, law, and medical schools). This course sequence teaches the integration of concepts of mechanical vibrations, acoustics, digital signal processing, and machinery dynamics. Overall, the concepts of noise control are related to product design, manufacturing, materials, performance, and economic considerations.

Sample Course Descriptions

Traditionally, topics and coverage in a graduate-level course tend to depend on the research expertise of the instructor, students’ backgrounds, and the needs of ongoing research programs. The characteristics of a sample course in noise and vibration control (with the emphasis on engineering practice) listed below are based on the third course at Ohio State.

  • Wave equation solutions: Three-dimensional acoustic cavities and basic sources, such as monopole and dipole.

  • Noise source identification: acoustic intensity using the two-microphone method, near-field holography, structural-acoustic responses using modal expansion, operating motion surveys, and laser scanning system.

  • Noise and vibration sources: (1) friction sources, such as brake squeal, belt vibration, and tire noise; (2) clearance sources, such as transmission rattle, door slam, and piston slap; (3) aerodynamic sources, such as vehicle components, alternators, and antennas

  • Passive and active noise and vibration control methods applicable to fluid and structural sources and paths.

  • Topics for case studies and guest lecturers include the development of experimental facilities, structureborne noise paths in products, muffler system tuning, statistical energy analysis applied to interior acoustics, international design and marketing (from the noise control perspective), ethics, and professionalism.

The following course description is based on Penn State’s Noise Control Engineering III:

  • Sources of noise: power transmission, electric equipment, nonturbomachinery, flow-induced, and turbomachinery.

  • Outdoor noise and structural acoustics: outdoor noise propagation, transportation noise, response of propagation in and radiation from structures, coupled structures.

  • Measurement and analysis: single- and two-channel frequency analyses, coherence, and transfer functions.

  • Noise treatments: vibration mounting systems, damping treatments, mufflers and silencers, active noise, and vibration control.

  • Modeling: finite and boundary element methods, statistical energy analysis.

Faculty should consider offering noise control courses that provide a balance between theory and engineering practice without sacrificing academic rigor. Classroom education can be augmented by field trips, guest lectures, and seminars. Industry, government laboratories, and consulting firms could provide valuable help by offering their facilities for course-related experiments or miniprojects. A graduate internship program would motivate students while building a cadre of future noise control engineers.

CONTINUING EDUCATION AND SKILL DEVELOPMENT

Distance Education

Changes in products, competitive features, and regulations continue to create a need for expertise in noise control engineering. Companies and agencies often fill these needs by calling on employees who know the business well and can assume these responsibilities in addition to or in lieu of their regular jobs. Because of a paucity of formally trained noise control engineers in most companies, these emerging requirements are often assigned to engineers with training in fields that may overlap with noise control engineering (e.g., aerodynamics, crash-worthiness, physics, mechanical engineering, vibrations, or electrical engineering) or to individuals with no previous experience with noise control engineering who are judged to have outstanding skill in other areas (e.g., product design). These new “noise control prac-

Suggested Citation:"9 Education Supply and Industry Demand for Noise Control Specialists." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
×

titioners” often need opportunities for professional development outside of formal educational settings. In fact, there are many venues for professional development, such as distance education through universities, short-course offerings from universities or private sources, and conferences.

Distance education offerings are often modified versions of university courses. Ohio State, Penn State, and Purdue University offer courses via video link and over the Internet.

Ohio State offers a one-year sequence of three quarter-long courses developed as a noise and vibration control engineering sequence for General Motors. The sequence is offered in the distance learning mode (via asynchronous video recordings and synchronous webex/video conferences). In addition, the sequence is offered biennially to approximately 15 to 30 students at General Motors and 15 to 25 graduate students at Ohio State.

In the past, Penn State offered a three-course sequence in the fundamentals of acoustics and noise control, but it was discontinued when the developer and instructor of the course retired. The sequence was offered asynchronously (at each student’s preferred pace) through Internet and video recordings. Total enrollment was approximately 100. However, Penn State continues to offer many courses through distance education that are fundamental to noise control engineering: Fundamentals of Acoustics, Digital Signal Processing, Electroacoustic Transducers, Acoustics in Fluid Media, Acoustical Data Measurement and Analysis, Techniques for Solving Acoustic Field Problems, Sound/Structure Interaction, Flow-Induced Noise, Audio Engineering, Sound Quality, Computational Acoustics, and Nonlinear Acoustics. More than 70 students enroll in these courses each semester. Upon successful completion of 30 credits, a student is awarded a master of engineering degree in acoustics.

Purdue offers five courses in acoustics and vibrations, through the IHETS interactive video network and by videotape, to several companies that have contracted courses through the university. Courses are offered on a two- or four-year cycle, depending on their popularity. Approximately 20 students take these courses each year.

All of these distance-learning courses, which are slightly modified versions of courses offered on campus in formal noise control engineering or acoustics programs, include homework and test requirements. Students may sign up for a graduate degree program through distance education with these courses as part of a plan of study or they may take them on a nondegree status as courses of interest. In either case, the courses are rigorous and provide a strong general background in acoustics, vibrations, and noise control engineering.

Short Courses

Short courses are available from universities and private sources. Courses run from a single day to one week and are generally intensive but offer little hands-on experience and no competency tests. University offerings tend to be adapted versions of coursework for which a need has been identified.

Short courses can be divided into two groups: (1) general courses that teach fundamental topics and (2) advanced courses specific to an emerging area of interest. General courses tend to serve the same audience as distance education courses, usually individuals who do not have access to distance education or who think a short course meets their needs in terms of logistics or learning methodology. Students in advanced courses tend to be well educated in the fundamentals of noise control engineering but need to learn about emerging or advanced topics. However, students in an advanced course often have different backgrounds and different levels of understanding, which make teaching such courses a challenging undertaking. Examples of advanced short courses include topics in signal processing, active noise control techniques, and nonlinear vibrations.

Short courses offered by private sources include both general and advanced topics. Many of these courses were developed to address common recurrent or customer problems or to educate potential customers who might use the services offered by the sponsoring company. A few courses are used as marketing tools to attract business or create new opportunities for the company. For example, a one-day course on the basics of acoustic measurement might be a demonstration of a new acoustical measurement device.

A large proportion of continuing education in noise control engineering is provided by private sources. Short courses, whether offered by universities or private companies, often attract students with diverse backgrounds, cover materials as quickly as possible with maximum possible retention, and motivate participants to learn subjects that may not have been of immediate interest.

Technical Conferences

Technical conferences are widely used as educational vehicles, perhaps more in noise control engineering than in other fields. About 1,400 people attend the biennial SAE (Society of Automotive Engineers) International Noise and Vibration Conference and Exhibition, which generally has fewer than 300, mostly practical, presentations. The educational mission of the conference is described in the brochure for the 2009 event (http://www.sae.org/events/nvc/):

The SAE Noise and Vibration Conference and Exhibition—the only dedicated mobility noise, vibration and harshness 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 innovations all under one roof. Attendees will gain a full understanding of NVH and sound quality issues related to vehicle design, engineering and testing, learn the latest trends

Suggested Citation:"9 Education Supply and Industry Demand for Noise Control Specialists." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
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and solutions during the technical paper presentations, visit innovative organizations at the exhibition, and exchange ideas with industry peers from around the world during special networking opportunities. This is a must-attend event!

The event includes approximately a dozen affiliated short courses, as well as workshops, demonstrations, and a large exhibition of products and materials.

Technical conferences sponsored by the Institute of Noise Control Engineering (NOISE-CON and INTER-NOISE), the National Research Council Transportation Research Board (summer meeting of the Transportation Noise Committee), and the American Institute of Aeronautics and Astronautics (Aeroacoustics Conference) place less emphasis than SAE on learning and more on technical exchanges by technical leaders. However, practitioners who want to learn something attend all of the conferences; all of them offer short courses in conjunction with the event.

Conclusion

Because the demand for noise control engineers is much greater than the supply of formally trained engineers, distance education and continuing education play a large role in developing practitioners in the field. The strongest offerings play a valuable role and should be encouraged to continue. However, many offerings compromise quality for expediency or marketability. Nevertheless, both will continue to be important for the foreseeable future. Therefore, guidelines associated with a certification process for noise control engineering in continuing education programs would help participants gauge the content and value of courses and other offerings.

SUPPLY-SIDE CHALLENGES

A major challenge to an adequate supply of well-trained noise control engineers is that educational programs are not homogeneous. For “mainstream” engineering disciplines, organizations such as ABET (http://www.abet.org/requirements) dictate that a majority of engineering departments at universities across the nation offer similar courses and cover the same general content. However, there are no such requirements for noise control engineering. A number of university departments offer education in noise control engineering either as degree programs, continuing or distance education, or both. However, even though they may sound alike, these departments often look very different. In comparing university departments, two characteristics vary dramatically—the size of the department and the school or discipline in which the department is housed.

Departments that have attained a critical mass of faculty members trained in noise control engineering often offer substantial courses and research opportunities. However, a large number of other departments have only one or two faculty members with training in noise control engineering. The database of the Acoustical Society of America (ASA) identifies universities that offer programs in various subdisciplines of acoustics.1 A search for “noise and noise control” reveals that of the 39 universities identified, only eight have more than two faculty members in the area of noise control engineering. Although these individuals may be well respected in the field, it is difficult for students in those programs to receive the same level of education as they would in a larger program.

Noise control engineering programs are also housed in a variety of departments. According to the ASA database, the majority are housed in mechanical engineering or aerospace engineering departments. However, the others can be found in departments of electrical engineering, physics, civil engineering, oceanography, architecture, communication science and disorders, recording arts and sciences, speech pathology, and audiology, and other unlikely departments, such as agriculture, otolaryngology, and biomaterials. Figure 9-1 shows the percentages of faculty members associated with departments identified as offering noise control engineering programs.

Lack of Homogeneity

The lack of homogeneity reflects the multidisciplinary nature of noise control engineering, which creates some benefits but also several challenges. The benefit is in bringing people from different backgrounds into the field who can contribute valuable new perspectives. One of the major challenges is that there is no consistent “home” for the discipline on university campuses.

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—primarily mechanical and electrical engineering. Today most are housed in mechanical engineering departments, although, as indicated above, many other departments are involved in noise control engineering education. This lack of a focal point can make it difficult for employers or anyone else looking for help in the area of noise control engineering to know exactly what to look for—a mechanical engineer, a physicist, an electrical engineer, or someone else.

Another challenge is that people trained in different engineering and scientific disciplines tend to look at problems from different perspectives and use different terminologies, each of which has advantages and disadvantages. The three main (complementary) perspectives are:

1

This database is cited because it may be less biased to a given discipline than some other databases. For example, the American Society of Mechanical Engineers (ASME) may be biased toward mechanical engineers, the American Institute of Aeronautics and Astronautics (AIAA) may be biased toward aerospace engineering, and the Institute of Electrical and Electronics Engineers (IEEE) may be biased toward electrical engineers.

Suggested Citation:"9 Education Supply and Industry Demand for Noise Control Specialists." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
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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 U.S. noise control programs in university departments. Source: Reprinted with permission from Scott D. Sommerfeldt, Brigham Young University.

  • analysis in terms of acoustic or structural modes

  • analysis in terms of wave propagation

  • analysis in terms of sound levels and noise metrics

Many noise control applications are typically analyzed in terms of acoustic or structural modes. This approach is useful for analyzing finite structures or enclosed sound fields, and considering a problem in terms of the modal response of a system can yield considerable insight. This approach could address problems in the sound field in rooms, automobiles, aircraft, and equipment enclosures, or the vibration response of equipment, transformers, housings, and so forth. The modal approach can also be useful for analyzing sound/structure interactions (i.e., when there is significant coupling of a vibrating structure and the fluid into which the structure radiates).

However, a modal approach is not effective for addressing acoustical problems in large areas, such as community noise. For these and other applications a wave propagation approach is typically used. Wave propagation analysis is applicable to community noise problems involving source radiation and sound propagation, reflection/transmission problems, acoustical properties of porous materials, sound propagation in heating and ventilation systems, and mufflers.

Over the years, noise control terminology using frequency averaging and other attempts to account for human perceptions of sound have been developed to support an engineering approach to noise control. A substantial portion of noise control engineering involves the use of metrics based on sound levels (expressed in decibels).

Each application area in noise control engineering tends to have several metrics that are particularly useful for that application. This raises two potential difficulties. First, some people who work in noise control engineering were never taught the concept of sound levels and may be uncomfortable using metrics. Second, many who have been exposed to basic metrics like sound pressure level are unfamiliar, and hence uncomfortable, with metrics used in other application areas. In either case, additional training in metrics (both definitions and how they are used to characterize noise) would be beneficial.

These three complementary, intertwined descriptions of noise control analysis can create an obvious problem. People with different educational backgrounds may have been exposed to only one or perhaps two of these approaches (e.g., modes and sound levels) but not the third approach (metrics). Even if they have been exposed to all three, the quality of education can vary dramatically. The problem is more pronounced at institutions that do not have large programs where there are not enough resources for students to be exposed to the full range of approaches. This problem is also common for individuals not trained in acoustics and noise control who were assigned to work on noise control applications by their employers. In most cases they are familiar with only one approach and must somehow make up that deficiency to be effective. Thus, they must have access to educational opportunities, and they must take advantage of them.

The multidisciplinary nature of noise control engineering also contributes to challenges for industry employers, who may expect new employees to understand sound propagation,

Suggested Citation:"9 Education Supply and Industry Demand for Noise Control Specialists." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
×

acoustic and structural absorption, reflection/transmission phenomena, instrumentation and measurement techniques, basic data and signal processing, computational techniques, and some basic psychoacoustics.

To address the challenges just described, it would be helpful for noise control engineering educators to establish a standard core curriculum for noise control engineering programs. Specialized coursework would also be desirable, but a standard curriculum would at least ensure that fundamental core concepts are understood by all students trained in the field. However, given the variety of departments that house noise control engineering programs, a standard curriculum is not likely to be adopted, unless an external body, such as ABET, pushes to implement a standard core curriculum.

DEMAND FROM INDUSTRY

Low-noise levels are becoming increasingly important for many products. In the cabin of vehicles, for example, low noise is strongly associated with high quality, as evidenced by the number of automobile commercials for high-end products that emphasize noise reduction features designed into the vehicle. The low-noise characteristics of appliances are also emphasized in sales literature and advertisements. We increasingly hear about public resistance to airport expansion or construction based on environmental noise. Similar resistance has been raised to expansion or construction of highways. Occupational environments are also concerned about workers’ exposure to noise. Considering the growing interest in noise control in all of these areas, the demand for noise control engineers in all fields will also grow.

Automobile Companies

Automakers compete on the basis of cost, perceived quality, safety, and fuel mileage. Noise reduction has been closely associated with high quality, as has been apparent in television and print advertising over the past decade. Automobile companies have even become interested in tuning the noise of vehicles for so-called sound quality. Traditionally, the top 10 warranty issues include troublesome noises and vibrations, such as squeaks and rattles. In addition, reducing noise overall usually meant adding weight to the vehicle, which reduced fuel mileage.

Thus, noise control engineering is a significant aspect of all parts of automobile design, from the conceptual phase when targets are set and basic architecture is decided to the finishing touches. In fact, engineers are needed at all levels and in all operations of companies, ranging from noise control specialists capable of setting targets and diagnosing problems to noise-aware designers capable of incorporating noise control strategies into routine design decisions.

Currently, many automotive companies have only enough noise control engineers to staff central noise control laboratories. The staff operates in a reactive mode to fix problems after most decisions have been made. Component suppliers often do not have any staff or laboratories for noise control design and therefore depend heavily on consultants. Thus, unnecessary noise problems arise, especially for fans, motors, transmissions, and pumps.

Aircraft Companies

Aircraft companies are concerned with reducing both interior and exterior aviation noise. Because weight is an important factor in the design of airplanes, the interior of an airplane is highly susceptible to both airborne and structure-borne engine noise and wind-rush noise caused by airflow over the fuselage. Thus, noise controls must be lightweight and highly efficient.

Noise control engineering for aircraft must begin at the conceptual design phase and continue through the development of the detailed design and prototype. Airframe companies such as Boeing hire aggressively and have noise control engineering personnel throughout the company. Boeing also invests intensively in continuing education to ensure that engineering designers in general are sensitive to noise reduction methodologies.

Exterior aircraft noise has received considerable attention. Policy has dictated a 10 dB per decade reduction in aircraft noise and mandated the retirement of a major portion of the fleet. Cost estimates for achieving this goal are as high as $5 billion. The noise control engineers who carried this effort forward were employed by aircraft engine manufacturers and the National Aeronautics and Space Administration.

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 control than they were in the past. Most of the noise control engineers involved in current studies have advanced degrees in acoustics with expertise in aerodynamics.

Noise Reduction in Other Areas

Purchasers of appliances also associate quiet with quality. Companies that plan to market their products internationally where buyers live in densely populated settings must provide quiet appliances to meet market regulations. Many appliance manufacturers have built small noise control laboratories, but they do not have critical mass to retain noise control engineers in a market in which demand greatly exceeds the supply.

In defense applications, noise control is not as uniformly important as it is in the commercial sector—with a few notable exceptions. During the cold war, acoustical detection of submarines and the suppression of the acoustical signature of submarines were high-priority technologies. During those years, very large numbers of noise control engineers, consultants, and contractors were employed in defense agencies. Noise reduction is still a significant aspect of stealth

Suggested Citation:"9 Education Supply and Industry Demand for Noise Control Specialists." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
×

weapons systems for air, ground, and naval applications, and noise control engineering is widely used in all branches of defense. The U.S. Department of Defense (DOD) has shown significant interest in personnel who can assist with hearing protection and other occupational safety issues. Some of the largest veterans’ benefits payouts are for hearing loss suffered by DOD personnel.

Consulting Companies

Based on membership in the National Council of Acoustical Consultants, it is estimated that approximately 2,000 noise control and acoustical consultants are practicing in the United States, and the number continues to grow. Consulting companies occupy a unique position between the public and either government or commercial operations. Effective noise control engineering consultants must not only understand the fundamentals of the field, but must also have the skills to understand policy and interact with a variety of clients, including real estate developers, construction companies, hospitals, municipal governments, and others. The situation was aptly described in a private communication to the committee by Senior Vice President Nicholas Miller of Harris Miller Miller & Hanson, Inc., a leading consulting company in transportation noise:

Since there seems to be very little education at the undergraduate level in noise control or acoustics, we do not expect to find people with undergraduate degrees with knowledge of acoustics. On the other hand, by the time they have done a serious MS or PhD in acoustics, they are likely overqualified for the positions we need. We often hire people with little or no knowledge of noise and acoustics and train them internally for the skills we need. Widespread undergraduate exposure to the basics of noise and acoustics would help us identify and retain good staff.

DOES DEMAND EXCEED SUPPLY?

The answer to the question of whether demand exceeds supply is based on responses collected during a workshop held in Reno in October 2007 as part of the NOISE-CON 2007 Conference and on other sources. This issue was also a subject of discussion at a National Academy of Engineering noise control research workshop in June 2008. Both workshops and an informal survey of engineers working in the field indicate that there is a strong demand for graduates in noise control engineering.

The same results were found in a poll of key academics in U.S. institutions who say they regularly receive phone calls and e-mail asking about graduate students with skills in noise control engineering. The number of practicing engineers in continuing education classes who have backgrounds significantly outside noise control engineering also indicates an undersupply of well-qualified graduates. University departments with educational opportunities related to noise control engineering generally report that inquiries about graduates qualified in noise control engineering and related disciplines exceed the local supply. Another indication of an imbalance between supply and demand comes from educators, who report that salary offers for new graduates with backgrounds in noise control are higher than for other engineers and that these students often receive multiple offers.

The consensus at both workshops was that graduate programs in noise control engineering should be expanded and that funding for current educational programs should be increased to ensure a steady supply of young professionals entering the field. In addition, undergraduate studies in noise control engineering should be expanded to ensure the availability of workers who can perform engineering tasks, such as making measurements and design calculations at the basic engineering levels. This would not only answer a need of employers but would also free practicing engineers (generally trained in other disciplines) who have difficulty with some approaches to noise control that are counterintuitive.

For American industries to produce quieter, more competitive products for domestic and global markets, noise emission and associated issues (such as costs, environmental considerations, and system design issues) must be added to the list of product and equipment requirements. This will mean that design and manufacturing engineers must understand some elements of noise control engineering and closely related engineering disciplines. There is also a need for qualified personnel in government for policy development and enforcement.

FINDINGS AND RECOMMENDATIONS

Undergraduate education in noise engineering varies greatly from institution to institution in terms of the department 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 research (or teaching) and to develop a new cadre of professionals is inadequate. The geographic distribution of leading programs is also a concern. The largest programs tend to be where funds for sponsored research are available rather than where industry demand for specialists is highest.

Recent reports highlighting the state of engineering education in the United States, such as The Engineer of 2020: Visions of Engineering in the New Century (NAE, 2004), which offers “future scenarios of the possible world conditions for the 2020 engineer,” recommend changes in engineering curricula and pedagogical methods. The report recommends that practical and interdisciplinary issues that impact society and industry, such as ethics, safety, and environment, should be integrated into the undergraduate engineering curriculum. A recent report by the Carnegie Foundation for the Advancement of Teaching (Sheppard et al., 2009) finds that “American engineering education is too theoretical and not hands-on enough…. A widespread emphasis on theory over

Suggested Citation:"9 Education Supply and Industry Demand for Noise Control Specialists." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
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practice … discourages many potential students while leaving graduates with too little exposure to real-world problems and ethical dilemmas.” The study committee of the present report believes that the promotion of noise control engineering in academia is consistent with the recommendations and visions of both reports, that it would fit the ABET criteria for engineering programs, and that it would serve the needs of related programs, such as physics, architecture, biological sciences, and speech and hearing.

The multidisciplinary nature of noise control engineering poses challenges for engineering practice and for lifelong learning. Typically, employees attempting to solve complex noise control problems must have a rigorous knowledge of noise measurement and signal processing techniques, propagation of noise though air and structures (including acoustic absorption, insulation, damping, and vibration isolation), computational techniques, and psychoacoustics. They may also need additional expertise in specific areas of noise control engineering (e.g., aero-acoustic problems are very different from problems raised by noise from machine elements). Neither undergraduate nor graduate programs are comprehensive, and the need to understand new issues and technologies over time creates a strong demand for continuing education.

Elements of noise control engineering degree programs should be formally taught in an intra- or interdisciplinary way by faculty in academic units (in engineering, physical sciences, and architecture). Major professional societies (such as AIAA, ASME, American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Institute of Noise Control Engineering of the USA, SAE). and other stakeholders should organize symposia (or special sessions in regular conferences), where leading academic and industry leaders can propose and refine curricula and suggest improvements in teaching methods and delivery mechanisms. Collaboration among academic, research, and industry leaders will be necessary for the development of interesting case studies or practice modules that could then be disseminated to teachers of undergraduate courses.

Funding is particularly important for research on environmental noise that encourages interdisciplinary collaboration between acousticians, engineers, social scientists, psychologists, sociologists, and health scientists to develop improved metrics for evaluating the impact of noise, including annoyance, speech and communications interference, cognitive impairment, sleep disturbance, and health effects.

A comparison of research activity on environmental noise in Europe, Japan, and the United States clearly reveals that the level of activity in Europe and Japan far exceeds the level in the United States. Substantial funding for research in Europe and Japan has enabled very large scale and many smaller scale studies. An indirect effect of this funding is the number of graduate students in environmental noise being educated in Europe and Japan, which has resulted in widespread understanding of acoustics and environmental problems and helped inform decisions and encouraged the adoption of noise mitigation efforts and appropriate metrics.


Recommendation 9-1: Academic institutions should offer an undergraduate course in noise control engineering, broaden the scope of the engineering curriculum, and increase the pool of engineering graduates who are equipped to design for low-noise emissions. The course could be offered as an elective in a bachelor’s degree program or as part of a minor (e.g., in acoustics or interdisciplinary studies).


Recommendation 9-2: Graduate-level noise control courses should provide a balance between theory and engineering practice without sacrificing academic rigor. The committee strongly encourages the establishment of graduate internships in industry and government agencies and thesis research programs to motivate students and to build a cadre of future noise control engineers.


Recommendation 9-3: Federal agencies, private companies, and foundations with a stake in noise control should provide financial support for graduate students who assist in research on, and the teaching of, noise control engineering. This support is crucial for the development of noise control professionals and noise control educators.

REFERENCES

NAE (National Academy of Engineering). 2004. The Engineer of 2020: Visions of Engineering in the New Century. Washington, DC: National Academies Press.

Sheppard, S.D., W.M. Sullivan, A. Colby, K.Macatangay, and L.S. Shulman. 2009. Educating Engineers: Designing for the Future of the Field. The Carnegie Foundation for the Advancement of Teaching. San Francisco, CA: Jossey-Bass.

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Exposure to noise at home, at work, while traveling, and during leisure activities is a fact of life for all Americans. At times noise can be loud enough to damage hearing, and at lower levels it can disrupt normal living, affect sleep patterns, affect our ability to concentrate at work, interfere with outdoor recreational activities, and, in some cases, interfere with communications and even cause accidents. Clearly, exposure to excessive noise can affect our quality of life.

As the population of the United States and, indeed, the world increases and developing countries become more industrialized, problems of noise are likely to become more pervasive and lower the quality of life for everyone. Efforts to manage noise exposures, to design quieter buildings, products, equipment, and transportation vehicles, and to provide a regulatory environment that facilitates adequate, cost-effective, sustainable noise controls require our immediate attention.

Technology for a Quieter America looks at the most commonly identified sources of noise, how they are characterized, and efforts that have been made to reduce noise emissions and experiences. The book also reviews the standards and regulations that govern noise levels and the federal, state, and local agencies that regulate noise for the benefit, safety, and wellness of society at large. In addition, it presents the cost-benefit trade-offs between efforts to mitigate noise and the improvements they achieve, information sources available to the public on the dimensions of noise problems and their mitigation, and the need to educate professionals who can deal with these issues.

Noise emissions are an issue in industry, in communities, in buildings, and during leisure activities. As such, Technology for a Quieter America will appeal to a wide range of stakeholders: the engineering community; the public; government at the federal, state, and local levels; private industry; labor unions; and nonprofit organizations. Implementation of the recommendations in Technology for a Quieter America will result in reduction of the noise levels to which Americans are exposed and will improve the ability of American industry to compete in world markets paying increasing attention to the noise emissions of products.

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