A Career in Acoustics engineering
Acoustic Engineering or Acoustical Engineering is the branch of engineering dealing with sound and vibration. According to the Acoustical Society of America, the term ‘acoustics’ refers to the science of sound, the behavior of sound waves in different environments and the ways that sound energy can be transformed into electrical energy. It relates to recorded music, speech and hearing, the behavior of sound in concert halls and buildings, and to noise in our environment. It is the application of acoustics, the science of sound and vibration, in technology. Acoustical engineers are typically concerned with the design, analysis and control of sound.
The field of ACOUSTICS, because its diverse nature offers many different career opportunities. The field of acoustic engineering may lead to a number of different positions related to the transmission and recording of sound. Acoustic engineers may consult with construction engineers and architects on the design and sound quality of facilities like performance spaces and recording studios. They may also ensure that buildings comply with local noise ordinances and standards, or they may work to minimize the noise caused by highway and air traffic. Some acoustic engineers work in audio engineering, designing sound systems. Others work in bio-engineering to develop medical devices, such as hearing aids.
The various sub disciplines of Acoustics Engineering are discussed below. They are loosely based on the PACS (Physics and Astronomy Classification Scheme) coding used by the Acoustical Society of America.
Aeroacoustics is concerned with how noise is generated by the movement of air, for instance via turbulence, and how sound propagates through the fluid air. Aeroacoustics plays an important role in understanding how noise is generated by aircraft and wind turbines, as well as exploring how wind musical instruments work
Audio signal processing
Audio signal processing is the electronic manipulation of audio signals using analog and digital signal processing. Audio signal processing is done for a variety of reasons such as:
- to enhance a sound, for instance by applying an audio effect such as reverberation;
- to remove unwanted noises from a signal, for instance echo cancellation on Skype;
- to compress an audio signal to allow efficient transmission, e.g. perceptual coding in MP3 and Opus, and
- to understand the content of the signal, e.g. music information retrieval to allow the identification of music tracks via Shazam (service).
Audio engineers develop and use audio signal processing algorithms.
Bioacoustics usually concerns the scientific study of sound production and hearing in animals. It can include:-
- Acoustic communication and associated animal behaviour and evolution of species
- How sound is produced by animals
- Auditory mechanisms and neurophysiology of animals
- Use of sound to monitor animal populations
- Effect of man-made noise on animals.
This branch of acoustic engineering deals with the design of headphones, microphones, loudspeakers, sound systems, sound reproduction and recording. There has been a rapid increase in the use of portable electronic devices which can reproduce sound and rely of electroacoustic engineering, e.g. mobile phones, portable media players, and tablet computers.
Musical acoustics is concerned with researching and describing the physics of music and its perception – how sounds employed as music work. This includes: the function and design of musical instruments including electronic synthesizers; the human voice (the physics and neurophysiology of singing); computer analysis of music and composition; the clinical use of music in music therapy, and the perception and cognition of music
Noise control is a set of strategies to reduce noise pollution by reducing noise at its source, by inhibiting sound propagation using noise barriers or similar, or by the use of ear protection (earmuffs or earplugs). Control at the source is the most cost-effective way of providing noise control. Noise control engineering applied to cars and trucks is known as noise, vibration, and harshness (NVH). Other techniques to reduce product noise include vibration isolation, application of acoustic absorbent and acoustic enclosures. Acoustical engineering can go beyond noise control to look at what is the best sound for a product, for instance manipulating the sound of door closures on automobiles.
Psychoacoustics tries to explain how humans respond to what they hear, whether that is an annoying noise or beautiful music. In many branches of acoustic engineering, a human listener is the final arbitrator as to whether a design is successful, for instance, whether sound localization works in a surround sound system. “Psychoacoustics seeks to reconcile acoustical stimuli and all the scientific, objective, and physical properties that surround them, with the physiological and psychological responses evoked by them.
Speech is a major area of study for acoustical engineering, including the production, processing and perception of speech. This can include physics, physiology, psychology, audio signal processing and linguistics. Speech recognition and speech synthesis are two important aspects of the machine processing of speech. Ensuring speech is transmitted intelligibly, efficiently and with high quality; in rooms, through public address systems and through telephone systems are other important areas of study.
Underwater acoustics is the scientific study of sound in water. It is concerned with both natural and man-made sound and its generation underwater; how it propagates, and the perception of the sound by animals. Applications include sonar to locate submerged objects such as submarines, underwater communication by animals, observation of sea temperatures for climate change monitoring, and marine biology.
Vibration and dynamics
Acoustic engineers working on vibration study the motions and interactions of mechanical systems with their environments, including measurement, analysis and control. This might include: ground vibrations from railways and construction; vibration isolation to reduce noise getting into recording studios; studying the effects of vibration on humans (vibration white finger); vibration control to protect a bridge from earthquakes, or modelling the propagation of structure-borne sound through buildings.
Architectural acoustics deals with sound in and around buildings of all kinds. Good acoustical design ensures the efficient distribution of desirable sounds as well as the exclusion of undesirable sound. It is the branch of acoustics that comes most readily to mind when a layperson thinks of “acoustics.”
Nearly everyone is aware of the importance of good acoustical design in concert halls, recording studios, auditoriums, and churches. But people spend more of their time in homes, offices, factories, or classrooms where little or no attention may have been given to the acoustical environment. Good acoustics should, and can, be engineered during the design of the building, since changes at a later time are expensive.
Growing public awareness of the importance of good acoustical design in buildings of all types will lead to a greater need for acoustical specialists and greater emphasis on acoustics in the training of architects, engineers, and other building professionals.
Engineering acoustics deals with transducers and sound measuring instruments of all kinds. A transducer is a device that converts sound energy into some other type of energy or vice versa. A microphone converts sound energy into electrical energy, a loudspeaker converts electrical energy into sound energy.
Engineering acoustics also includes instrumentation for medical diagnosis, communications, seismic surveying, recording and reproducing speech and music, and other challenging problems.
Most universities do not offer a degree specifically in acoustical engineering, but professionals in engineering acoustics may have degrees in electrical, mechanical, or aeronautical engineering, physics, or related areas. Engineers with training and experience in acoustics are very much in demand in industry.
Electroacoustics is a branch of engineering acoustics that deals with microphones, loudspeakers, and other transducers, as well as the recording and reproduction of sound.
In Europe there are special courses to prepare a person for the position of “tonmeister,” one who is trained in both music and engineering. In this country such a person might be called an “audio engineer” or a “musical engineer” and the position might be that of “recording director” or “technical director.” Needless to say, these positions are very much sought after. A strong preparation in music, acoustics, and electronics is necessary. Most entrants into the professional audio field begin as audio technicians to gain the necessary experience.
Persons who combine a solid background in acoustics with education or experience in business are very much in demand in the rapidly growing audio entertainment industry. A candidate is well advised to include courses in digital electronics, and computer programming because of the growing importance of digital sound processing and recoding in the audio field.
Musical acoustics deals with the way in which we hear and perceive musical sound, the instruments that produce it, and even the structure of melody and harmony. It combines elements of both the arts and science.
A number of researchers in this area study the way in which sound is produced in musical instruments. Others study subjective qualities of musical sound, such as pitch, loudness, and timbre. Much attention has focused recently on the use of digital computers to produce sound and to compose music.
Persons with training and experience in musical acoustics frequently work in the entertainment industry, in education, in recording and film studios, or in the musical instrument industry. It is a rewarding field for someone with a strong interest in music as well as in science.
Noise has been receiving increasing recognition as one of our critical environmental pollution problems. Like air and water pollution, noise pollution increases with population density. In our urban areas, it is a serious threat to the quality of life. Noise-induced hearing loss is a major health problem. Noise also robs us of sleep and interferes with communication.
Solving a noise problem requires an understanding of the noise source, the path of the sound, and the receiver (usually a person or group of people). The best place to control noise is at the source, but frequently control of the path and protection of the receiver are necessary as well.
Finding technical solutions to our environmental noise problems requires the work of scientists and engineers with considerable knowledge of acoustics. Since many problems require political or social action, knowledge of political science, sociology, and the law are important as well.
Physical Acoustics deals with the way in which sound waves propagate in solids, liquids, gases, and plasmas, and how they interact with these materials. Of special interest are sound waves of very high frequency (more that one billion vibrations per second) and very high intensity. High-frequency sound waves in solids are called phonons because they behave like particles. At temperatures near absolute zero, scientists have observed some strange waves that are called “second sound,” “third sound,” etc. Observing their behavior has helped physicists understand the quantum behavior of liquids.
Subatomic particles, such as protons, muons, and even the elusive neutrino, have been detected by the sound they make as they travel at high speeds through the ocean.
Many new frontiers exist in this exciting field of research. Most researchers have advanced degrees in physics.
Speech and Hearing
The ability to communicate by spoken language is unique to man. We tend to take speech communication for granted, yet many aspects of it all still not completely understood. Some speech scientists are engaged in basic studies of speech production and perception, while others design machines that recognize verbal messages or individual speakers. Research that seeks to understand how man produces and perceives speech is leading to the development of methods for improved communication between man and machine and for more effective training and technical aids for those with disorders of communication.
Of equal importance is a better understanding of hearing. Our ability to perceive and appreciate the sounds around us is essential, both for our survival and for our pleasure. Although we have learned much from past research about the capabilities of the auditory system, much remains to be discovered about its underlying physiological and psychological mechanisms. Scientists interested in hearing are currently studying the peripheral ear, the neural pathway to the brain, and higher-order processing of acoustic information. Potential benefits of this research include improved transmission of acoustic signals for use by man, more effective procedures to detect abnormal development of hearing in children, and meaningful guidelines for the protection of hearing in an increasingly noisy environment.
The use of acoustic energy to “see” or detect objects underwater is analogous to the use of radar for detecting objects in air. In much the same way that an aircraft is guided through a blinding storm by its radar system, underwater vessels such as submarine are guided through the depths of the ocean by their acoustic systems.
Since the characteristics of the water environment permit sound to be transmitted over very long distances, sometimes hundreds of miles, sound is an extremely valuable tool, not only for military applications but also for commercial use. Acoustic signals are used to detect the presence and location of commercially valuable fish, to map the sea floor to determine the safest “avenues” for supertankers, and to explore the Earth’s geological formations or search for oil deposits beneath the ocean floor.
The need for technological advancements in underwater acoustics will continue to grow over the next decade as man attempts to utilize the sea to the fullest advantage. This growth will afford many rewarding job opportunities for graduates in acoustics.
Bioacoustics and Medical Acoustics
Bioacoustics deals with the interaction of sound waves with biological tissues in humans and animals. Much recent research in this area has been concerned with the use of high-frequency ultrasound in medical diagnosis and treatment. Use of ultrasound in diagnosis avoids some of the danger involved in using x rays and other types of radiation.
Some bioacousticians study the mechanisms by which animals produce acoustic signals and the ways in which other animals detect and process these signals. Dolphins, bats, and certain species of insects have been widely studied.
Excellent career opportunities exist in this interdisciplinary field for students with an interest in biology and medical science as well as in acoustics and physics.
Structural Acoustics and Vibration
Vibration is a principal concern of engineers. Large machines must be designed such that their operation is “smooth,” without unwanted vibration. Electronic components of aerospace systems can be damaged by excessive vibration and sudden jolts (mechanical shocks), but a clever engineer can put basic scientific principles to work to discover ways of either eliminating the possibility of such vibration or of isolating sensitive equipment from its vibrating environment. Many “disasters,” such as the destruction of a building by an earthquake, the toppling of a tall smokestack, or the collapse of a suspension bridge in a windstorm, involve vibration, but engineers are continuing to learn new ways of lessening the chance of these disasters taking place.
Since unwanted noise is often caused by vibration, when one seeks to control noise at its source, the problem often reduces to eliminating or altering vibration. There are also a multitude of applications where vibration is essential, such as in stringed and percussion instruments, in the design of loudspeakers, in the testing of metallic parts for flaws, in the transporting of very hot metal parts on moving and vibrating conveyor belts, and in the removal of dirt and soot from surfaces.
Solving a vibration problem often requires the detective skill of a Sherlock Holmes to get to the root of the problem. Not only is the mathematics involved often very sophisticated, but it also requires a great deal of common sense and ingenuity to express the real world situation in terms of mathematical relations that can yield useful insights. Since such skills and abilities are in great demand, many vibration engineers are active as consultants, giving advice to other engineers to help solve their vibration problems.
Employers typically require acoustic engineers to have at least a 4-year degree in electrical engineering or a similar field. Some engineering programs allow students to focus on specific areas of acoustic engineering, such as sound system engineering or vibrations. Students in these programs take core engineering classes, such as electrical circuits, fluid mechanics, statics, thermodynamics and heat transfer. Acoustics-related coursework may cover such topics as architectural acoustics, sound reinforcement, noise control, vibrations and environmental acoustics. Some jobs in acoustic engineering require a master’s degree. The master’s-level curriculum may include coursework in underwater acoustics, medical ultrasonic, wave propagation, signal processing, optics, electromechanical transducers and nonlinear acoustics. Depending on the program, students may have to complete a thesis or study project.
Acoustic engineers have the following traits:
- Technical and mechanical knowledge in the field, especially as it relates to electrical engineering, physics, music, audiology and architecture
- Ability to work well with a team
- Excellent written and oral communication skills
- Manual dexterity
- Problem-solving skills
- Excellent hearing
Employment and Salary Outlook
Acoustic Engineer (professional)
Acoustic engineers usually possess a bachelor’s degree or higher qualification in acoustics, physics or another engineering discipline. Practicing as an acoustic engineer usually requires a bachelor’s degree with significant scientific and mathematical content. Acoustic engineers might work in acoustic consultancy, specializing in particular fields, such as architectural acoustics, environmental noise or vibration control. In other industries, acoustic engineers might design automobile sound systems, investigate human response to sounds, such as urban soundscapes and domestic appliances, develop audio signal processing software for mixing desks, and design loudspeakers and microphones for mobile phones. Acousticians are also involved in researching and understanding sound scientifically. Some positions, such as faculty require a Doctor of Philosophy.
In most countries, a degree in acoustics can represent the first step towards professional certification and the degree program may be certified by a professional body. After completing a certified degree program the engineer must satisfy a range of requirements before being certified. Once certified, the engineer is designated the title of Chartered Engineer in most Commonwealth countries.
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