...Acoustics From Wikipedia, the free encyclopedia (Redirected from Acoustical) Jump to: navigation, search For other uses, see Acoustics (disambiguation). Artificial omni-directional sound source in an anechoic chamber Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. 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 application of acoustics is present in almost all aspects of modern society with the most obvious being the audio and noise control industries. Hearing is one of the most crucial means of survival in the animal world, and speech is one of the most distinctive characteristics of human development and culture. Accordingly, the science of acoustics spreads across many facets of human society—music, medicine, architecture, industrial production, warfare and more. Art, craft, science and technology have provoked one another to advance the whole, as in many other fields of knowledge. Robert Bruce Lindsay's 'Wheel of Acoustics' is a well accepted overview of the various fields in acoustics.[1] The word "acoustic" is derived from the Greek word ακουστικός (akoustikos), meaning "of or for hearing, ready to hear"[2] and that from ἀκουστός (akoustos), "heard, audible",[3] which in turn derives from the verb ἀκούω (akouo), "I...
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...Objective of the study 1.4. Methodology Chapter: two – Concepts and description of relative terms 2.1. Basic acoustic considerations for auditorium design 2.2. How to Calculate of reverberation time 2.3. Background of evolution of auditorium over the last century Chapter: three –BIAM Auditorium 3.1. Description of BIAM Auditorium Chapter: one: 1.1.Introduction: The study has been taken as part of the masters in architecture course titled “Sonic environment and built-form, course no. arch 6102 and the objective of was to study an auditorium for its acoustics solution. There are several auditoriums in the Dhaka city. The BIAM auditorium has been taken for the case study of an auditorium because of its great usage for performances. 1.2. Background of the study: The acoustics in an auditorium must facilitate a wide range of activities during performances, from percussion and different music from the stage, choirs, delivering speech and singing. These real-time shifts in acoustic demands should be well-served by variable acoustic systems to the reverb time of the space. To identify the acoustical conditions of the auditoriums in the Dhaka city and have several acoustical solutions of them the study is planned. 1.3. Objective of the study: The purpose of the paper is to study the contextual acoustic condition of the particular auditorium and find out the acoustic solutions for it. And this will be followed by a study of the BIAM auditorium. 1.4. Methodology: The methods...
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...Logarithms and Levels Logarithms are used to compare two quantities to one another quickly with an easy frame of reference. It is particularly useful if there is a large difference in orders of magnitude between quantities as in acoustic pressure or acoustic energy calculations. We will see how useful logarithms can be in our next lesson. For now, let's concentrate on review of some of the basic principles leading up to our use of logarithms. Unless otherwise stated, we will be working solely with logarithms that are in base 10 (Briggsian) . Some useful relationships to remember when working with logarithms are: 1. y = 10x then log10 ( y ) = x 2. log ( xy ) = log ( x ) + log ( y ) ⎛x⎞ 3. log ⎜ ⎟ = log ( x ) − log ( y ) ⎝ y⎠ ( ) 4. 10 log x n = n10 log( x ) Intensity Level In the last lesson, we defined the time average intensity in relation to the time average or rms pressure as well as the maximum acoustic pressure. p2 p2 I = = max 2ρc ρc The intensity is a useful quantity because it quantifies the power in an acoustic wave, but because of the large variation in magnitudes of Intensity, it is more useful to use logarithms to compare intensities. The below table demonstrates the wide variation in Intensity for typical sounds in air. We will start by defining a new quantity, L, the intensity level, which has units of dB. I L ≡ 10 log I0 where: is the time average intensity of the sound wave. I0 is the reference level used for comparison...
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...THIS DOCUMENT IS PROTECTED BY U.S. COPYRIGHT It may not be reproduced, stored in a retrieval system, distributed or transmitted, in whole or in part, in any form or by any means. Downloaded from SAE International by Brunel University, Copyright 2012 SAE International Saturday, January 21, 2012 01:04:43 PM SAE TECHNICAL PAPER SERIES 2008-01-0892 An Optimization of Dual Continuously Variable Valve Timing for Reducing Intake Orifice Noise of a SI Engine Teockhyeong Cho, Youngki Kim, Jaeheon Kim and Koo-tae Kang Hyundai Motor Company Reprinted From: Noise and Vibration, 2008 (SP-2158) 2008 World Congress Detroit, Michigan April 14-17, 2008 400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-0790 Web: www.sae.org THIS DOCUMENT IS PROTECTED BY U.S. COPYRIGHT It may not be reproduced, stored in a retrieval system, distributed or transmitted, in whole or in part, in any form or by any means. Downloaded from SAE International by Brunel University, Copyright 2012 SAE International Saturday, January 21, 2012 01:04:43 PM By mandate of the Engineering Meetings Board, this paper has been approved for SAE publication upon completion of a peer review process by a minimum of three (3) industry experts under the supervision of the session organizer. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording...
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...signal Speech Signal Processing Speech Production Speech Waveform Characteristics ● ● ● Loudness Voiced/Unvoiced. Pitch. – Fundamental frequency. Formants. ● Spectral envelope. – Speech Waveform Characteristics Voiced Unvoiced s s Short-Time Speech Analysis ● Segments (or frames, or vectors) are typically of length 20 ms. – – Speech characteristics are constant. Allows for relatively simple modeling. ● Often overlapping segments are extracted. The Spectrogram ● A classic analysis tool. – Consists of DFTs of overlapping, and windowed frames. ● Displays the distribution of energy in time and frequency. A spectrogram Short time ACF /m/ /ow/ /s/ ACF |DFT| Sound Propagation Sound propagates from the source to the receiver through a combination of four main propagation modes: ● ● ● ● direct propagation path reflection from walls diffraction around objects refraction due to temperature differences in the layers of air. For that reason sound is delayed and attenuated by different amounts. Reflection One happens when a sound wave encounters a medium with different impedance from which it is travelling in, for example when the sound propagating in the air hits the walls of a room (fig. 1). Sound reflects from walls, objects, etc. Acoustically, reflection results in: Sound reverberation - for small round-trip delays (less than 100 ms), Echo - for longer round-trip delays. fig. 1 ● ● ...
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...Ultrasound It is an assured and apparent fact that the progression of society has for the most part trailed the widening and advancement in our understanding of science and technology. Over the past centuries, such advancements has led to some of the most innovative and groundbreaking inventions in human history. The post-World War II era saw some of these basic inventions and discoveries leap into next level advancements with the help of new technology. One of the areas that benefitted largely from the technological advancements is our health care industry. With the latest innovative medicine, doctors and researchers can now do what was unthinkable in the past century or before. One small example of such innovative technology used in today’s health care industry is the Cardiac Ultrasound Machine. Our understanding of physics has helped in better diagnosing problems without having to perform invasive procedures like before. The world of imaging in medical sciences and treatment has benefitted the most from this understanding. In today’s health care, sound waves such as the ultrasounds have changed diagnostic procedures for ever. This fact is exemplified in the invention of Cardiac Ultrasound Machine. The machine mainly consists of a transducer probe, central processing unit, transducer pulse controls, display and keyboard, storage device and a printer. The functionality of the machine depends on the piezoelectric crystals and their ability to generate sound with the absorbance...
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...Facility Planning Consideration Tanyale Bell HCS/446 April 27, 2015 Richard Nordahl Abstract Facility Planning Consideration In this following paper I will discuss the regulatory requirements and their effect on design and equipment. This paper will give audiences detail on color selection implication and noise issues, electronic items needed, and Gantt chart that details and implementation plan. Thus, this evidence will give resource and facts of examination of budget planning and cost estimates, a list of different type of equipment needed, the description of the role of stakeholders’ in facility planning and development. For many years regulation and technical requirement have been affected by less needs and pressures. Which include workforce shortage, malpractice insurance and reimbursement. Although, since 60 to 75% of hospital expenses are labor costs, a design that increases operational productivity or efficiency and reduces staffing needs can have a major impact on the bottom line. (www.wbdg.org/design). Thus, regulatory requirements has an effect on state, local and federal laws. Many ordinance have more stringent requirement, such as zoning laws and building codes. In additional safety laws and other laws have to address before construction started. Federal and state laws relating to privacy (HIPAA), waste management (OSHA & EPA), environmental hazards (OSHA & EPA), and other emerging concerns have the potential to affect the design of a dental clinic...
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...EXCEPTIONAL PERFORMANCE: High acoustic combination head and chestpiece DURABLE CONSTRUCTION: Stainless steel ear tubes and combination chestpiece PATIENT COMFORT: Dual non-chill rings provide a comfortable experience for patients COMFORTABLE FIT: Soft, comfortable silicone ear tips are used to create a complete acoustic seal, minimizing ambient noise LIGHTWEIGHT: Flexible PVC tubing is used in the standard single lumen design Product Description: Produce remarkably clear acoustics with Vive Precision’s stethoscope. The comfortable, lightweight Vive Precision stethoscope is a single lumen design with a durable stainless steel diaphragm for detecting high frequencies and a small bell for detecting low frequency and auscultatory sounds....
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...1. OLANREWAJU VICTOR FADARE 2. a Ans Lawnmower (Yardman-Gas riding). I found it on lawnmower database and has sound pressure level of 92.3dBA b. Ans 98.3dBA= 2*92.3 Dba. This is because the scale measurement is logarithmic and every time the sound increases by 6dBA, the sound intensity doubles. c. Ans 86.3dBA 3. a. Ans This is a legal requirement set by OSHA, authorizing employers to keep their employees at an exposure limit at 90dB or below it for an average 8-hour duration. b. ans 2.3dB 4. a. Ans This is a limit set by NIOSH and it is based on noise intensity that is able to cause loss in hearing if an employee is exposed to daily at work throughout their career. b. Ans 7.3dB 5. Imagine you are an occupational health professional in an industry where workers are exposed to the noise source you selected in question 2. Tell which standard you would adopt to protect your workers (the PEL or REL). Defend your answer by discussing your hearing protection goals as they relate to the different purposes of the PEL and REL. Length of answer: 20-40 words. Ans 6. a. Ans Moldex pura-fit; PF220 and has a NRR of 33 b. Ans This is the highest intensity of sound that can be achieved using hearing protection under standard situation and an NRR of 33 means under ideal situation it can reduce a workers exposure to noise by as much as 33dB. c. Ans This is because the noise dosimeter is measured to A-scale which is used for sensitivity of human ear to various sound frequencies while...
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...CONTENTS S.No Titles Page No Introduction 1. Classification of Noise 1 1.1 Community Noise 2 1.2 Occupational Noise 2 2 Effect of Noise on Public Health 3 3 Noise Standards in Pakistan 4 3.1 Motor Vehicle Rules, 1969 5 4 Studies and Data for Removal of Pressure Horns in Different Cities of Pakistan 6 4.1 Environmental Protection Agency, NWFP 6 4.2 Environment Protection Department, Punjab 6 5 Major Steps Taken by Ministry of Environment 7 8 References 8 INTRODUCTION Noise is an unwanted, unpleasant and annoying sound caused by vibration of the matter. Vibrations impinge on the ear drum of a human or animal and setup a nervous disturbance, which we call sound. When the effects of sound are undesirable that it may be termed as “Noise”. Noise from industry, traffic, homes and recreation can cause annoyance, disturb sleep and affect health. Thus, sound is a potentially serious pollutant and threat to environmental health. The response of the human ear to sound depends both on the sound frequency (measure in Hertz, Hz) and the sound pressure, measured in decibels (dB). A normal ear in healthy young person can detect sounds with frequencies from 20Hz to 20,000 Hz. Noise measurements are expressed by the term Sound Pressure Level (SPL) which is logarithmic ratio of the sound pressure to a reference pressure and is expressed as a dimensionless unit of power, the decibel (dB). The reference level...
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...wave. A sound wave consists of moving a source from one place to another; this is done by its energy being transferred. How is sound measured? Firstly the energy of a sound wave is called the Amplitude and this is related the perceived loudness. This is sometimes represented as a sound pressure. Secondly the number of cycles completed in one second is called frequency of the vibration. It is often the frequency that determines the pitch. This is always measured in Hz (hertz). Finally sound can be measured by the distance it travels, sound travels at approximately 760mph. Definition of Acoustics Acoustics is the effect that a surrounding area/environment can have on sound. Acoustics specifically relating to media. Acoustics is often referred to as the science of sound relating to the production, transmission, recording or the detection of sound. In the true sense of the word, acoustics is the area that you chose to record sound and how that particular area affects the sound recording. Sound can sound different depending on the environment, for example if the sound is in a large empty area then the sound will echo, however if it is in...
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...Switch-Mode DC-AC Inverters 1. 2. 3. 4. 5. Introduction Basic Concepts of Switch-Mode Single-Phase Inverters Three-Phase Inverters Effects of Blanking Time on Output Voltage in PWM 6. Rectifier Mode of Operation • Main applications: – ac motor drives; – uninterruptible power supplies; – grid connection of renewable energy sources 1 1 Switch-Mode DC-AC Inverter • Block diagram of a motor drive where the power flow is unidirectional FEUP-MIEEC. Industrial Electronics 2 2 Switch-Mode DC-AC Inverter • Block diagram of a motor drive where the power flow can be bi-directional FEUP-MIEEC. Industrial Electronics 3 3 Switch-Mode DC-AC Inverter • Four quadrants of operation FEUP-MIEEC. Industrial Electronics 4 One Leg of a Switch-Mode DC-AC Inverter • The mid-point shown is fictitious • Similar to the topology dc - dc for two-quadrants operation FEUP-MIEEC. Industrial Electronics 5 Synthesis of a Sinusoidal Output by PWM Carrier wave (triangle) Modulating wave (sine) Amplitude modulation index: ma = ˆ Vm ˆ Vtri Frequency modulation index: mf = fs f1 • Typical harmonic spectrum shows voltage components around multiples of the switching frequency FEUP-MIEEC. Industrial Electronics 6 Details of a Switching Time Period • Control voltage can be assumed constant during a switching time-period FEUP-MIEEC. Industrial Electronics 7 Analysis of output voltage • In the inverter...
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...Physics of sound Sound is a mechanical wave, sequence of waves is resulting from an air pressure disturbance produced by vibration, and sound propagates through the medium such as air or water. During the propagation, sound can be reflected or attenuated by the medium. Humans can hear the sound is because the vibration pass the wave in to our ear, this is called Traveling Longitudinal Waves. The propagation of the sound can be affected by the density and pressure. The temperature determines the speed of sound with in the medium, also the medium itself would affect the propagation such as wind (moving medium) if the medium is moving therefore the wave would propagated further; with the medium don’t have viscosity, sound would be easier to propagate, but if the medium have an negative viscosity such as water the it would affects the motion of the sound wave. On the top is the diagram of the travellingwave the bar above the diagram represent the concentrations of the pressures on the wave, when the curve are compression (the part above the horizontal line) it represent a high pressure; when the curve are rarefaction (the part below the horizontal line) it represent a low pressure and they change from one to another, this pattern repeats indefinitely. Speed of sound = wavelength*Frequency Wavelength (it can be written as λ) is the distance between two consecutive corresponding points of a waveform. Normally the wavelength is about a meter long. The pitch/frequency of the...
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...TECHNICAL UNIVERSITY OF KENYA DEPARTMENT OF CIVIL AND CONSTRUCTION ENGINEERING ENVIRONMENTAL ENGINEERING ASSIGNMENT 111/00502 SAMSON NYAMWEYA INSTRUCTOR: PROFESSOR THUMBI ASSIGNMENT: NOISE FROM CONSTRUCTION, CIVIL ENGINEERING WORKS AND ITS CONTROL Contents INTRODUCTION 3 MEASURES THAT CAN BE TAKEN TO CONTROL NOISE POLLUTION FROM CONSTRUCTION SITES. 4 Community notification 4 Operate plant in a quiet and efficient manner 4 Involve workers in minimizing noise 5 Handle complaints 5 Location of plant 5 Alternatives to reversing alarms 5 Maximize shielding 6 Schedule activities to minimize noise impacts 6 NOISE FROM CONSTRUCTION SITES INTRODUCTION Construction sites are often located near existing residential accommodation and by their nature are noisy and open sites. Residents will in general accept construction site noise due to their temporary status. However, if works starts early or finishes late or if it takes place on a Saturday afternoon, Sunday or public holiday noise complaints may be likely. In many areas, the recommended hours of operation for construction are: * Monday - Friday: Start 7:30am (with a restriction on the hours of operation heavy plant and machinery and major demolition and construction works until 8:00am) and finish at 6pm. * Saturday: Start 9am. And Finish at 1pm. * Sundays and Bank Holidays: No work permitted. Construction plant and equipment noise levels can be described in two ways: * sound power level (Lw or SWL), or ...
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...|Need of Sound in Films | | | |Sound is used in a film to add emotion and rhythm. Sound makes the film even better. The rhythm, melody, harmony and instrumentation of the music| |can strongly affect the viewer’s emotional reactions. Sound engages a distinct sense which can lead to “synchronization of senses” making a | |single rhythm or expression unify both image and sound. The effects of sound are often largely subtle and often are noted by only our | |subconscious minds. Sound effects can set the whole mood for a movie. Not only sound effects are used in every film but also simple melodies so | |as to make the film more sentimental, cheerful, and frightening. A meaningful sound track is often as complicated as the image on the screen. A | |good movie can make the viewer forget they're watching a movie. But if the sound is bad, it takes us right out of the experience and reminds that| |not only the sound, but the scenery and acting is all make believe. So, the more senses of human body are used, the better because it makes it | |real. | |Secondly,...
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