Acoustical Engineering

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National Aeronautics and Space Administration Engineering is Out of This World! Acoustical Engineering NASA is developing a new rocket called the Space Launch System, or SLS. The SLS will be able to carry astronauts and materials, known as payloads. Acoustical engineers are helping to build the SLS. Sound is a vibration. A vibration is a rapid motion of an object back and forth. Hold a piece of paper up right in front of your lips. Talk or sing into the paper. What do you feel? What do you think is causing the vibration? If too much noise, or acoustical loading, is ! caused by air passing over the SLS rocket, the vehicle could be damaged by the vibration! NAME: (Continued from front) Typical Sound Levels in Decibels (dB) Experiment with the paper. 130 — Jet takeoff Does talking louder or softer change the vibration? 120 — Pain threshold 110 — Car horn 100 — Motorcycle Is the vibration affected by the pitch of your voice? (Hint: Pitch is how deep or 90 — Power lawn mower ! high the sound is.) 80 — Vacuum cleaner 70 — Street traffic —Working area on ISS (65 db) Change the angle of the paper. What 60 — Normal conversation happens? 50 — Rain 40 — Library noise Why do you think NASA hires acoustical 30 — Purring cat engineers? (Hint: Think about how loud 20 — Rustling leaves rockets are!) 10 — Breathing 0 — Hearing Threshold How do you think the noise on an airplane compares to the noise on a rocket? Hearing protection is recommended at ! 85 decibels. NASA is currently researching ways to reduce the noise made by airplanes. In what ways does an airplane make noise? (If you haven’t flown, think of riding in your family car or standing on a busy street corner.) www.nasa.gov #SLSInspires EP-2013-12-152-MSFC.

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2014 Newsletter for the Robert Bradford Newman Student Award
NEWSLETTER 2014 OBERT RADFORD EWMAN RS T U D EB N T A W A R DN F U N D 2014 AT A GLANCE Yiying Hao Adam Lawrence Paul Faculty Advisor: Jian Kang Faculty Advisor: Bob Celmer December 31, 2014 completed another University of Sheffield University of Hartford successful year for the Newman Fund. “Effects of urban morphology on urban “Acoustic evaluation of Austen Arts Center, Newman Medals were awarded to 19 stu- sound environment from the perspective of Trinity College for Smith Edwards McCoy dents, bringing the total to 290 at more masking effects” Architects” than 58 schools of architecture, engineer- ing, music and music technology since the Robert Healey Zhao Ellen Peng program began in 1985. Of particular note Faculty Advisor: Bob Coffeen Faculty Advisor: Lily Wang is the increased participation from schools University of Kansas University of Nebraska – Lincoln and programs outside North America. “Investigations into the sound absorbing “How room acoustics impacts speech com- properties of gypsum wall board” prehension from talkers and by listeners Five student teams received Wenger priz- with varying English proficiency levels” es in 2014 for their meritorious design Christina Higgins work juried and displayed at the ASA Faculty Advisor: Stephen Dance Ariana F. Sharma Student Design Competition held at the London South Bank University Faculty Advisor: David T. Bradley 167th meeting of the Acoustical Society “An investigation into the Helmholz Vassar College in Providence, RI. There were sixteen total resonators of the Queen Elizabeth Hall, “Effect of installed diffusers on sound field entries submitted to the SDC from a num- London” diffusivity in a real-world classroom” ber of different universities.
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Standing Waves and Sound
Standing Waves and Sound Waves are vibrations (jiggles) that move through a material Frequency: how often a piece of material in the wave moves back and forth. Waves can be longitudinal (back-and- forth motion) or transverse (up-and- down motion). When a wave is caught in between walls, it will bounce back and forth to create a standing wave, but only if its frequency is just right! Sound is a longitudinal wave that moves through air and other materials. In a sound wave the molecules jiggle back and forth, getting closer together and further apart. Work with a partner! Take turns being the “wall” (hold end steady) and the slinky mover. Making Waves with a Slinky 1. Each of you should hold one end of the slinky. Stand far enough apart that the slinky is stretched. 2. Try making a transverse wave pulse by having one partner move a slinky end up and down while the other holds their end fixed. What happens to the wave pulse when it reaches the fixed end of the slinky? Does it return upside down or the same way up? Try moving the end up and down faster: Does the wave pulse get narrower or wider? Does the wave pulse reach the other partner noticeably faster? 3. Without moving further apart, pull the slinky tighter, so it is more stretched (scrunch up some of the slinky in your hand). Make a transverse wave pulse again. Does the wave pulse reach the end faster or slower if the slinky is more stretched? 4. Try making a longitudinal wave pulse by folding some of the slinky into your hand and then letting go.
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Nuclear Acoustic Resonance Investigations of the Longitudinal and Transverse Electron-Lattice Interaction in Transition Metals and Alloys V
NUCLEAR ACOUSTIC RESONANCE INVESTIGATIONS OF THE LONGITUDINAL AND TRANSVERSE ELECTRON-LATTICE INTERACTION IN TRANSITION METALS AND ALLOYS V. Müller, G. Schanz, E.-J. Unterhorst, D. Maurer To cite this version: V. Müller, G. Schanz, E.-J. Unterhorst, D. Maurer. NUCLEAR ACOUSTIC RESONANCE INVES- TIGATIONS OF THE LONGITUDINAL AND TRANSVERSE ELECTRON-LATTICE INTERAC- TION IN TRANSITION METALS AND ALLOYS. Journal de Physique Colloques, 1981, 42 (C6), pp.C6-389-C6-391. 10.1051/jphyscol:19816113. jpa-00221175 HAL Id: jpa-00221175 https://hal.archives-ouvertes.fr/jpa-00221175 Submitted on 1 Jan 1981 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. JOURNAL DE PHYSIQUE CoZZoque C6, suppZe'ment au no 22, Tome 42, de'cembre 1981 page C6-389 NUCLEAR ACOUSTIC RESONANCE INVESTIGATIONS OF THE LONGITUDINAL AND TRANSVERSE ELECTRON-LATTICE INTERACTION IN TRANSITION METALS AND ALLOYS V. Miiller, G. Schanz, E.-J. Unterhorst and D. Maurer &eie Universit8G Berlin, Fachbereich Physik, Kiinigin-Luise-Str.28-30, 0-1000 Berlin 33, Gemany Abstract.- In metals the conduction electrons contribute significantly to the acoustic-wave-induced electric-field-gradient-tensor (DEFG) at the nuclear positions. Since nuclear electric quadrupole coupling to the DEFG is sensi- tive to acoustic shear modes only, nuclear acoustic resonance (NAR) is a par- ticularly useful tool in studying the coup1 ing of electrons to shear modes without being affected by volume dilatations.
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View of Examinations
OFFICE OF THE SECRETARY OF STATE ARCHIVES DIVISION BEV CLARNO STEPHANIE CLARK SECRETARY OF STATE DIRECTOR A. RICHARD VIAL 800 SUMMER STREET NE DEPUTY SECRETARY OF STATE SALEM, OR 97310 503-373-0701 NOTICE OF PROPOSED RULEMAKING INCLUDING STATEMENT OF NEED & FISCAL IMPACT FILED 10/07/2019 2:19 PM CHAPTER 820 ARCHIVES DIVISION BOARD OF EXAMINERS FOR ENGINEERING AND LAND SURVEYING SECRETARY OF STATE FILING CAPTION: Amend rule related to the administration of the Oregon Specific Acoustical Examination LAST DAY AND TIME TO OFFER COMMENT TO AGENCY: 11/21/2019 5:00 PM The Agency requests public comment on whether other options should be considered for achieving the rule's substantive goals while reducing negative economic impact of the rule on business. A public rulemaking hearing may be requested in writing by 10 or more people, or by a group with 10 or more members, within 21 days following the publication of the Notice of Proposed Rulemaking in the Oregon Bulletin or 28 days from the date the Notice was sent to people on the agency mailing list, whichever is later. If sufficient hearing requests are received, the notice of the date and time of the rulemaking hearing must be published in the Oregon Bulletin at least 14 days before the hearing. CONTACT: Jenn Gilbert 670 Hawthorne Avenue, SE Filed By: 503-934-2107 Salem,OR 97301 Jenn Gilbert [email protected] Rules Coordinator NEED FOR THE RULE(S): To remove the Acoustical Engineering examination from those administered by the Board. The Board does not have an approved examination to test qualifications for licensure specifically to the the Acoustical branch.
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Recent Advances in the Sound Insulation Properties of Bio-Based Materials
PEER-REVIEWED REVIEW ARTICLE bioresources.com Recent Advances in the Sound Insulation Properties of Bio-based Materials Xiaodong Zhu,a,b Birm-June Kim,c Qingwen Wang,a and Qinglin Wu b,* Many bio-based materials, which have lower environmental impact than traditional synthetic materials, show good sound absorbing and sound insulation performances. This review highlights progress in sound transmission properties of bio-based materials and provides a comprehensive account of various multiporous bio-based materials and multilayered structures used in sound absorption and insulation products. Furthermore, principal models of sound transmission are discussed in order to aid in an understanding of sound transmission properties of bio-based materials. In addition, the review presents discussions on the composite structure optimization and future research in using co-extruded wood plastic composite for sound insulation control. This review contributes to the body of knowledge on the sound transmission properties of bio-based materials, provides a better understanding of the models of some multiporous bio-based materials and multilayered structures, and contributes to the wider adoption of bio-based materials as sound absorbers. Keywords: Bio-based material; Acoustic properties; Sound transmission; Transmission loss; Sound absorbing; Sound insulation Contact information: a: Key Laboratory of Bio-based Material Science and Technology (Ministry of Education), Northeast Forestry University, Harbin 150040, China; b: School of Renewable Natural Resources, LSU AgCenter, Baton Rouge, Louisiana; c: Department of Forest Products and Biotechnology, Kookmin University, Seoul 136-702, Korea. * Corresponding author: [email protected] (Qinglin Wu) INTRODUCTION Noise reduction is a must, as noise has negative effects on physiological processes and human psychological health.
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Psychoacoustics and Its Benefit for the Soundscape
ACTA ACUSTICA UNITED WITH ACUSTICA Vol. 92 (2006) 1 – 1 Psychoacoustics and its Benefit for the Soundscape Approach Klaus Genuit, André Fiebig HEAD acoustics GmbH, Ebertstr. 30a, 52134 Herzogenrath, Germany. [klaus.genuit][andre.fiebig]@head- acoustics.de Summary The increase of complaints about environmental noise shows the unchanged necessity of researching this subject. By only relying on sound pressure levels averaged over long time periods and by suppressing all aspects of quality, the specific acoustic properties of environmental noise situations cannot be identified. Because annoyance caused by environmental noise has a broader linkage with various acoustical properties such as frequency spectrum, duration, impulsive, tonal and low-frequency components, etc. than only with SPL [1]. In many cases these acoustical properties affect the quality of life. The human cognitive signal processing pays attention to further factors than only to the averaged intensity of the acoustical stimulus. Therefore, it appears inevitable to use further hearing-related parameters to improve the description and evaluation of environmental noise. A first step regarding the adequate description of environmental noise would be the extended application of existing measurement tools, as for example level meter with variable integration time and third octave analyzer, which offer valuable clues to disturbing patterns. Moreover, the use of psychoacoustics will allow the improved capturing of soundscape qualities. PACS no. 43.50.Qp, 43.50.Sr, 43.50.Rq 1. Introduction disturbances and unpleasantness of environmental noise, a negative feeling evoked by sound. However, annoyance is The meaning of soundscape is constantly transformed and sensitive to subjectivity, thus the social and cultural back- modified.
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Infrasound and Ultrasound
Infrasound and Ultrasound Exposure and Protection Ranges Classical range of audible frequencies is 20-20,000 Hz <20 Hz is infrasound >20,000 Hz is ultrasound HOWEVER, sounds of sufficient intensity can be aurally detected in the range of both infrasound and ultrasound Infrasound Can be generated by natural events • Thunder • Winds • Volcanic activity • Large waterfalls • Impact of ocean waves • Earthquakes Infrasound Whales and elephants use infrasound to communicate Infrasound Can be generated by man-made events • High powered aircraft • Rocket propulsion systems • Explosions • Sonic booms • Bridge vibrations • Ships • Air compressors • Washing machines • Air heating and cooling systems • Automobiles, trucks, watercraft and rail traffic Infrasound At very specific pitch, can explode matter • Stained glass windows have been known to rupture from the organ’s basso profunda Can incapacitate and kill • Sea creatures use this power to stun and kill prey Infrasound Infrasound can be heard provided it is strong enough. The threshold of hearing is determined at least down to 4 Hz Infrasound is usually not perceived as a tonal sound but rather as a pulsating sensation, pressure on the ears or chest, or other less specific phenomena. Infrasound Produces various physiological sensations Begin as vague “irritations” At certain pitch, can be perceived as physical pressure At low intensity, can produce fear and disorientation Effects can produce extreme nausea (seasickness) Infrasound: Effects on humans Changes in blood pressure, respiratory rate, and balance. These effects occurred after exposures to infrasound at levels generally above 110 dB. Physical damage to the ear or some loss of hearing has been found in humans and/or animals at levels above 140 dB.
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Qualifications Acoustical, Technology, and Lighting
HORBURN ASSOCIATES ACOUSTICAL, TECHNOLOGY, AND LIGHTING DESIGN Qualifications Acoustical, Technology, and Lighting Thorburn Associates (TA) specializes in the design and consulting of acoustics, technology, and lighting systems. We are involved with multiple market sectors which help to facilitate cross pollination of solutions between markets. With experience on over 2600 projects, one of TA’s strengths is our ability to provide an integrated solution for these technical aspects of the design. TA is a Woman‐owned Small Business Enterprise (WSBE) with offices located throughout the U.S. to serve your needs. Acoustical design combines art and science to modify noise to achieve a desired auditory environment. TA creates acoustical environments tailored to the occupants of each space. We combine our expertise with extensive laboratory and electronic testing equipment to meet the unique sound ACOUSTICAL sensitivities of each project. Room Acoustics – Sound Isolation – Mechanical Noise – Vibration Isolation – Environmental Noise Technology systems design is an ever‐growing industry bolstered by the constant demand for multimedia communications. TA works with our clients to develop the system that will best meet their needs while planning for and understanding maintenance, upgrade, and expansion needs. TECHNOLOGY Audiovisual Systems – Telepresence – Sound Masking/Paging – Structured Cabling – Security We specialize in illumination design, a term that describes aspects much broader than the standard overhead electric lighting system; illumination
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Sound Acoustics in the Workplace from the Floor up Image: Philips HQ, DACH 3
Sound acoustics in the workplace From the floor up Image: Philips HQ, DACH 3 Happy, healthy people make a better business When people feel comfortable in their The physical workplace environment plays a major workplace, they’re more productive. role. Employee well-being is vital to any Research has also shown that employees rank it organisation, and controlling noise is as one of the top three factors contributing to job central to this. satisfaction, as well as to their decisions about accepting or leaving a job. At Interface we know that our physical experiences impact on how we feel. And we understand the importance of having a great place to work. Designers and architects have a crucial role to play in providing inspirational environments that facilitate flexible working, for the benefit of both employers and employees. Image: Discovery, ZA Image: Discovery, Modular flooring for flexible, quieter spaces 5 Open-plan spaces are increasingly popular, as they support collaboration and creativity – but they can also be noisy. And disruptive sound levels are high on the list of workplace complaints. Generally, employees feel much happier and more relaxed if they can move around and interact freely with colleagues. But the open-plan design that allows this also poses acoustic challenges. To help solve this problem, we’ve developed modular flooring specifically for the changing workplace. Our extensive ranges of carpet tiles and LVT offer the variety of design, and versatility in function, you need to support all kinds of activities – from quiet concentration to teamwork and recreation. Modular flooring is also ideal for zoning areas for a range of activities, from collaboration and concentration to relaxation and recreation.
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Acoustics: the Study of Sound Waves
Acoustics: the study of sound waves Sound is the phenomenon we experience when our ears are excited by vibrations in the gas that surrounds us. As an object vibrates, it sets the surrounding air in motion, sending alternating waves of compression and rarefaction radiating outward from the object. Sound information is transmitted by the amplitude and frequency of the vibrations, where amplitude is experienced as loudness and frequency as pitch. The familiar movement of an instrument string is a transverse wave, where the movement is perpendicular to the direction of travel (See Figure 1). Sound waves are longitudinal waves of compression and rarefaction in which the air molecules move back and forth parallel to the direction of wave travel centered on an average position, resulting in no net movement of the molecules. When these waves strike another object, they cause that object to vibrate by exerting a force on them. Examples of transverse waves: vibrating strings water surface waves electromagnetic waves seismic S waves Examples of longitudinal waves: waves in springs sound waves tsunami waves seismic P waves Figure 1: Transverse and longitudinal waves The forces that alternatively compress and stretch the spring are similar to the forces that propagate through the air as gas molecules bounce together. (Springs are even used to simulate reverberation, particularly in guitar amplifiers.) Air molecules are in constant motion as a result of the thermal energy we think of as heat. (Room temperature is hundreds of degrees above absolute zero, the temperature at which all motion stops.) At rest, there is an average distance between molecules although they are all actively bouncing off each other.
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Acoustic GRIN Lens
California Polytechnic State University San Luis Obispo EE 462 Senior Project Advisor: Dean Arakaki Acoustic GRIN Lens Author Matthew Luu Date: June 12, 2020 Abstract Museum displays with audio explanations typically use headphones. A speaker’s sound at one display interferes with patrons at other displays, thus museums use headphones. These devices are either integrated into the display itself, or attached to an mp3 player. When integrated into the display, headphones can be unsanitary; when attached to an mp3 player, these devices are inconvenient. If speakers can direct sound toward an intended area, headphones can be eliminated. Acoustic horns direct sound toward a specific point, but require a large spatial footprint. Acoustic spherical concave lenses also direct sound toward a point, but exhibit excessive acoustic attenuation. Current speakers on the market that focus sound toward a location are costly compared to headphones. An acoustic gradient index of refraction lens, GRIN lens, accomplishes sound wave focusing while minimizing attenuation and decreasing material costs compared to current directive speakers. The goal of this project is to design and optimize a GRIN lens using numerical simulations in COMSOL Multiphysics and scripts developed in MATLAB. This GRIN lens must direct sound for museum exhibits; therefore, must operate in the human speech frequency band (300Hz - 3400Hz). An acoustic test chamber was designed and built in order to test and validate the physical prototype. The prototype was fabricated using PETG on the MakerGearM2 3D printer. This chamber is 1m length x 1m height x 1m depth and characterizes acoustic radiation pattern vs. azimuth angle (300Hz - 3400Hz) and the frequency response - microphone directly in front of speaker (300Hz - 10kHz) - for 3” maximum diameter speakers.
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Chapter 12: Physics of Ultrasound
Chapter 12: Physics of Ultrasound Slide set of 54 slides based on the Chapter authored by J.C. Lacefield of the IAEA publication (ISBN 978-92-0-131010-1): Diagnostic Radiology Physics: A Handbook for Teachers and Students Objective: To familiarize students with Physics or Ultrasound, commonly used in diagnostic imaging modality. Slide set prepared by E.Okuno (S. Paulo, Brazil, Institute of Physics of S. Paulo University) IAEA International Atomic Energy Agency Chapter 12. TABLE OF CONTENTS 12.1. Introduction 12.2. Ultrasonic Plane Waves 12.3. Ultrasonic Properties of Biological Tissue 12.4. Ultrasonic Transduction 12.5. Doppler Physics 12.6. Biological Effects of Ultrasound IAEA Diagnostic Radiology Physics: a Handbook for Teachers and Students – chapter 12,2 12.1. INTRODUCTION • Ultrasound is the most commonly used diagnostic imaging modality, accounting for approximately 25% of all imaging examinations performed worldwide nowadays • Ultrasound is an acoustic wave with frequencies greater than the maximum frequency audible to humans, which is 20 kHz IAEA Diagnostic Radiology Physics: a Handbook for Teachers and Students – chapter 12,3 12.1. INTRODUCTION • Diagnostic imaging is generally performed using ultrasound in the frequency range from 2 to 15 MHz • The choice of frequency is dictated by a trade-off between spatial resolution and penetration depth, since higher frequency waves can be focused more tightly but are attenuated more rapidly by tissue The information in an ultrasonic image is influenced by the physical processes underlying propagation, reflection and attenuation of ultrasound waves in tissue IAEA Diagnostic Radiology Physics: a Handbook for Teachers and Students – chapter 12,4 12.1.
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