Background on Acoustics (Part I) PDF - Building Utilities 3 Lecture

Here is the transcription of the document into a structured markdown format: # BACKGROUND ON ACOUSTICS (Part I) A Lecture for Building Utilities 3 Ar. Patrick N. Rodriguez Faculty Member-MLQU SOA ## BGU 322 BUILDING UTILITIES 3 ### What is Acoustics? * Acoustics is a branch of physics that dea...

Here is the transcription of the document into a structured markdown format: # BACKGROUND ON ACOUSTICS (Part I) A Lecture for Building Utilities 3 Ar. Patrick N. Rodriguez Faculty Member-MLQU SOA ## BGU 322 BUILDING UTILITIES 3 ### What is Acoustics? * Acoustics is a branch of physics that deals with the study of mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound. *-wikipedia* * Acoustics is the science concerned with the production, control, transmission, reception, and effects of sound. *britannica* * A scientist who works in the field of acoustics is an *acoustician* while someone working in the field of acoustics technology may be called an *acoustical engineer*. * The term is derived from the Greek *akoustos*, meaning "heard." ## BGU 322 BUILDING UTILITIES 3 ### Brief History of Acoustics #### Early Experimentation * The origin of the science of acoustics is generally attributed to the Greek philosopher *Pythagoras* (6th century BC), whose experiments on the properties of vibrating strings that produce pleasing musical intervals were of such merit that they led to a tuning system that bears his name. * Aristotle (4th century BC) correctly suggested that a sound wave propagates in air through motion of the air-a hypothesis based more on philosophy than on experimental physics; however, he also incorrectly suggested that high frequencies propagate faster than low frequencies-an error that persisted for many centuries. ## BGU 322 BUILDING UTILITIES 3 ### Brief History of Acoustics #### Early Experimentation * *Vitruvius*, a Roman architectural engineer of the 1st century BC, determined the correct mechanism for the transmission of sound waves, and he contributed substantially to the acoustic design of theatres. * In the 6th century AD, the Roman philosopher *Boethius* documented several ideas relating science to music, including a suggestion that the human perception of pitch is related to the physical property of frequency. ## BGU 322 BUILDING UTILITIES 3 ### Brief History of Acoustics #### Early Experimentation * The modern study of waves and acoustics is said to have originated with *Galileo Galilei* (1564-1642), who elevated to the level of science the study of vibrations and the correlation between pitch and frequency of the sound source. * The French mathematician *Marin Mersenne* studied the vibration of stretched strings; the results of these studies were summarized in the three Mersenne's laws. Mersenne's Harmonicorum Libri (1636) provided the basis for modern musical acoustics. ## BGU 322 BUILDING UTILITIES 3 ### Brief History of Acoustics #### Early Experimentation * Later in the century *Robert Hooke*, an English physicist, first produced a sound wave of known *frequency*, using a rotating cog wheel as a measuring device. * Further developed in the 19th century by the French physicist *Félix Savart*, and now commonly called *Savart's disk*, this device is often used today for demonstrations during physics lectures. * A card held to the edge of a spinning toothed wheel will produce a tone whose pitch varies with the speed of the wheel. ## BGU 322 BUILDING UTILITIES 3 ### Brief History of Acoustics #### Age of Enlightenment and Onward * Substantial progress in acoustics, resting on firmer mathematical and physical concepts, was made during the eighteenth century by *Euler* (1707-1783), *Lagrange* (1736-1813), and *d'Alembert* (1717-1783). * During this era, continuum physics, or field theory, began to receive a definite mathematical structure. * The wave equation emerged in a number of contexts, including the propagation of sound in air. * In the nineteenth century the major figures of mathematical acoustics were *Helmholtz* in Germany, who consolidated the field of physiological acoustics, and *Lord Rayleigh* in England, who combined the previous knowledge with his own copious contributions to the field in his monumental work *The Theory of Sound* (1877). $v=fλ$ ## BGU 322 BUILDING UTILITIES 3 ### Brief History of Acoustics #### Age of Enlightenment and Onward * The twentieth century saw a burgeoning of technological applications of the large body of scientific knowledge that was by then in place. * The first such application was Wallace Sabine's groundbreaking work in architectural acoustics (Boston Symphony Hall), and many others followed. * Underwater acoustics was used for detecting submarines in the first World War. * Sound recording and the telephone played important roles in a global transformation of society. * The ultrasonic frequency range enabled wholly new kinds of application in medicine and industry. ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics * The "*Wheel of Acoustics*" was created by R. Bruce Lindsay for The Science of Acoustics, published in the Journal of the Acoustical Society of America. * The wheel shows the fields of acoustics starting with the four broad fields of *Earth Sciences, Engineering, Life Sciences, and the Arts.* * The outer circle lists the various broad disciplines one may study to prepare for a career in acoustics. * The inner circle lists the fields within acoustics to which many fields naturally lead. An image of the "Wheel of Acoustics" - a circular diagram showing a central circle with the words "fundamental physical acoustics mechanical radiation in all material media phonons" at its center Around this are other fields, including; "acoustics physics", "electro", "physiology", "Hearing", "psychoacoustics psychology", "visual arts music arts", "Mechanical engineering", "seismic waves", "sound Underwater sound atmosphere", "bioacoustics" ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### General Acoustics * This category covers the science of sound and waves. * How sound is created, how it travels and how it is received. * How materials react to different types of sounds is also important in this field. * This field includes Engineering Acoustics, Physical Acoustics, and Signal Processing in acoustics, and others. ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### General Acoustics *Engineering Acoustics* * Acoustical engineering (also known as acoustic engineering) is the *branch of engineering dealing with sound and vibration*. * It includes 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. * One goal of acoustical engineering can be the *reduction of unwanted noise*, which is referred to as noise control. * Besides noise control, acoustical engineering also covers positive uses of sound, such as the use of ultrasound in medicine, programming digital synthesizers, designing concert halls to enhance the sound of orchestras and specifying railway station sound systems so that announcements are intelligible. ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### General Acoustics *Physical Acoustics* * Physical acoustics is the area of acoustics and physics that studies *interactions of acoustic waves with a gaseous, liquid or solid medium on macro- and micro-levels*. * This relates to the interaction of sound with thermal waves in crystals (phonons), with light (photons), with electrons in metals and semiconductors (acousto-electric phenomena), with magnetic excitations in ferromagnetic crystals (magnons), etc. ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### General Acoustics *Acoustic Signal Processing* * Acoustic signal processing is the *electronic manipulation of acoustic signals.* * Applications include: active noise control; design for hearing aids or cochlear implants; echo cancellation; music information retrieval, and perceptual coding ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Animal Bioacoustics * Animal bioacoustics is a field of research that encompasses sound production and reception by animals, animal communication, biosonar, active and *passive acoustic technologies for population monitoring, acoustic ecology, and the effects of noise on animals.* * Animal bioacousticians come from very diverse backgrounds: engineering, physics, geophysics, oceanography, biology, mathematics, psychology, ecology, and computer science. * Why study animal bioacoustics? The motivation for many is conservation. ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Animal Bioacoustics * Many animals are vocal, and, consequently, passive listening provides a noninvasive and efficient tool to monitor population abundance, distribution, and behavior. * Listening not only to animals but also to the sounds of the physical environment and man-made sounds, all of which make up a soundscape, allows us to monitor entire ecosystems, their health, and changes over time. * Understanding bioacoustic systems can advance the development of biomimetic technology such as *sonar hardware and software.* * Studying animal hearing and hearing impairment holds great potential for *understanding human hearing and mitigating human auditory injury and disease.* ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Animal Bioacoustics *Bioacoustic Monitoring in Species Biodiversity Research* * Human activity causes the disappearance of various animal species at an alarming rate, leading to a new crisis related to eradiation of biodiversity. * Many of the critically endangered species are very rare, mysterious animals that live in hiding, which will probably die out before they are fully documented. * Studies methods using automated bioacoustic recorders offer significant promise, especially for species whose behavior or ecology reduces their detectability using traditional methods. * Individual recognition by means of the acoustic features of vocalizations can be achieved in several animal taxa, from frogs to mammals and birds, and is one of the best examples of the application of acoustic analysis to population. ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics *Animal Bioacoustics* *Bioacoustic Monitoring in Measurement of Environmental Pollution* * Biotic and abiotic effects of climate change can also affect environmental acoustics and thus change communication between animals. This in turn leads to changes in entire soundscapes and affects biodiversity, as some species are unable to adapt quickly to changes in the environment. * Bioacoustics highly effectively serves as a tool for measuring the impact of human activities on the environment not only in the waters. Also on land we can estimate changes in the ecosystem by recording and analyzing sounds. ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Medical Acoustics * Doctors and medical researchers study and use acoustics to diagnose and treat different types of ailments. * The study of medical acoustics includes the use of ultrasound and other acoustical techniques to learn how different types of sound interact with cells, tissues, organs and entire organisms. * Biomedical acousticians may work with engineers, physicians and speech therapist. ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Medical Acoustics * Medical acoustics can be subdivided into diagnostics and therapy. * Diagnostics are further separated into auditory and ultrasonic methods, and both employ low amplitudes. * Therapy (excluding medical advice) uses ultrasound for heating, cooking, permeablizing, activating and fracturing tissues and structures within the body, usually at much higher amplitudes than in diagnostics. ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Musical Acoustics * Musical acoustics or music acoustics is a multidisciplinary field that combines knowledge from physics, psychophysics, organology (classification of the instruments), physiology, music theory, ethnomusicology, signal processing and instrument building, among other disciplines. * As a branch of acoustics, it is concerned with *researching and describing the physics of music* - how sounds are employed to make music. * Examples of areas of study are the function of musical instruments, the human voice (the physics of speech and singing), computer analysis of melody, and in the clinical use of music in music therapy. ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Musical Acoustics * The data and methods of general physical acoustics, which studies the processes of generation and propagation of sound, are used in musical acoustics. * It is *closely allied with architectural acoustics*, the psychology of perception, and the physiology of hearing and the voice. * An important step in the development of musical acoustics is associated with the eminent German physical scientist and physiologist H. L. F. von Helmholtz, who proposed the first complete conception of the physiology of pitch discrimination, called the resonance theory of hearing. ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Noise and Environmental Acoustics * Environmental acoustics is concerned with noise and vibration caused by railways, road traffic, aircraft, industrial equipment and recreational activities. * The main aim of these studies is to reduce levels of environmental noise and vibration. * Knowledge produced by these scientists can be used to redesign noisy machinery, or to recommend ways of shielding the noise, or to help lawmakers and public officials create rules for limiting exposure to noise. *-exploresound.org* ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Noise and Environmental Acoustics *Environmental acoustics may use different areas of expertise: *acoustic metrology*, when it comes to quantifying the noise emissions of a noise source (machinery, equipment) or the performance of products or construction systems in a laboratory or on site (materials for sound insulation, partitions, silencers) or the performance of sets such as enclosures (acoustic hoods), premises and buildings (in terms of sound insulation or in terms of reverberation) or when it comes to the characterization of an acoustic situation (e.g. the source of a discomfort) in accordance with applicable standards. ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Noise and Environmental Acoustics *Environmental acoustics may use different areas of expertise:* * *modeling*, when it comes to simulate the performance of products or construction systems (materials for acoustic insulation, walls, silencers) or the performance of sets such as enclosures (acoustic hoods), premises and buildings (in terms of sound insulation or in terms of reverberation) or the impact of a noise source for a given environment ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Noise and Environmental Acoustics *Environmental acoustics may use different areas of expertise:* * *construction technologies* (metal, wood, masonry) including the selection of products and construction systems (for sound insulation or soundproofing equipment or for reverberation control systems) possibly in the context of the construction / refurbishment of buildings with the management of related features in connection with the building process (mechanical strength, fire performance, thermal insulation). ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Noise and Environmental Acoustics *Environmental acoustics may use different areas of expertise:* * *knowledge of various industrial processes* involving equipment generating specific constraints and sometimes antagonistic with respect to acoustics (e.g. those linked to aerodynamics in general and to the treatment of hot or cold gas flows in particular in the area of energy or for test benches and testing rooms), and of the physics of heat transfer (in the field of production of heat, cooling) ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Noise and Environmental Acoustics *Environmental acoustics may use different areas of expertise:* * knowledge of noise sources related to transportation infrastructures (road & rail). ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Speech and Hearing * Hearing specialists and speech scientists are interested in how our ears sense sounds, what types of sounds can damage our ears and how speech is made, travels, and is heard. * People interesting in hearing and speech come from many different fields, including physics, speech and hearing science, experimental psychology, linguistics, electrical engineering, and others. * This field includes Speech Communication, Physiological and Psychological Acoustics, Noise, and others. ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Underwater Acoustics * Underwater Acoustics is the *study of sounds moving through water, such as the ocean, a lake or even water in a tank*. * Scientists in this field may study the surface of the water, deep underwater, or even close to the seabed or ocean floor. * This field includes Underwater Acoustics, Acoustical Oceanography, Animal Bioacoustics, Physical Acoustics, and others. ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Underwater Acoustics * Applications of underwater acoustics: * Sonar * Underwater navigation and tracking * Seismic exploration * Weather and climate observation * Oceanography * Marine biology * Particle physics ## BGU 322 BUILDING UTILITIES 3 ### Fields of Acoustics #### Architectural Acoustics *Architectural acoustics* (also known as building acoustics) is the *science and engineering of achieving a good sound within a building* and is a branch of acoustical engineering. * Architectural acoustics can be about achieving good speech intelligibility in a theatre, restaurant or railway station, enhancing the quality of music in a concert hall or recording studio, or suppressing noise to make offices and homes more productive and pleasant places to work and live in. * The first application of modern scientific methods to architectural acoustics was carried out by the American physicist Wallace Sabine in the Fogg Museum lecture room. He applied his newfound knowledge to the design of Symphony Hall, Boston.