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04-23-2011, 01:03 AM
several intriguing issues in acoustics entail the propagation of sound in ducts. furthermore, numerous programs of acoustics to ventilation / exhaust techniques in buildings and cars use mufflers and acoustic filters to scale back the level of noise propagating down a duct or radiating from your conclude of the duct. within this laboratory exercising you'll investigate the conduct of acoustic waves in a duct with modifications in cross-sectional place, aspect branches, and resonators. inside the process you'll observe the behavior of acoustic low-pass, high-pass, and band-stop filters because they are utilized inside a duct method. ii. the theory of acoustic transmission lines
a instead comprehensive theoretical development of acoustic waveguides, transmission lines,Office Pro Plus 2007 (http://www.office2007-key.eu/), and filters could possibly be identified in chapters 9 & 10 of fundamentals of acoustics,Windows 7 (http://www.office-2007-key.de/windows-7-key), 3rd ed., kinsler, frey, coppens, and sanders,Office Professional 2010 (http://www.office2007-key.us/office-2010-key), (j. wiley & sons, 1982). a. waveguides and transmission lines
a waveguide is a structure which forces wave propagation along a path parallel to its longest dimension. acoustic wavequides are structures with constant cross-sectional location and shape. simple examples of such structures include hoses,Windows 7 Enterprise (http://www.windows7keygen.us/), tubes, and pipes, referred to hereafter as ducts. if a duct is excited by a pressure disturbance with a wavelength larger than twice the duct's largest cross-sectional dimension, then only plane waves will propagate down the duct. for a circular duct containing air at room temperature, the highest frequency at which only plane waves will propagate is given by f = 100/a where a is the radius of the duct cross-section. once plane waves are generated inside the duct, they will propagate down the duct, even if the duct has bends or turns in it. a propagating plane wave may encounter a change inside the acoustic impedance of the duct when the duct (i) opens into free space,Windows 7 Key (http://www.office-2007-key.com/windows-7-key), (ii) is connected to another section of duct with a different cross-section, (iii) branches off into two ducts, or (iv) is terminated in some other way. this impedance change causes partial reflection and partial transmission of the incident plane waves.
a instead comprehensive theoretical development of acoustic waveguides, transmission lines,Office Pro Plus 2007 (http://www.office2007-key.eu/), and filters could possibly be identified in chapters 9 & 10 of fundamentals of acoustics,Windows 7 (http://www.office-2007-key.de/windows-7-key), 3rd ed., kinsler, frey, coppens, and sanders,Office Professional 2010 (http://www.office2007-key.us/office-2010-key), (j. wiley & sons, 1982). a. waveguides and transmission lines
a waveguide is a structure which forces wave propagation along a path parallel to its longest dimension. acoustic wavequides are structures with constant cross-sectional location and shape. simple examples of such structures include hoses,Windows 7 Enterprise (http://www.windows7keygen.us/), tubes, and pipes, referred to hereafter as ducts. if a duct is excited by a pressure disturbance with a wavelength larger than twice the duct's largest cross-sectional dimension, then only plane waves will propagate down the duct. for a circular duct containing air at room temperature, the highest frequency at which only plane waves will propagate is given by f = 100/a where a is the radius of the duct cross-section. once plane waves are generated inside the duct, they will propagate down the duct, even if the duct has bends or turns in it. a propagating plane wave may encounter a change inside the acoustic impedance of the duct when the duct (i) opens into free space,Windows 7 Key (http://www.office-2007-key.com/windows-7-key), (ii) is connected to another section of duct with a different cross-section, (iii) branches off into two ducts, or (iv) is terminated in some other way. this impedance change causes partial reflection and partial transmission of the incident plane waves.