several exciting difficulties in acoustics involve the propagation of sound in ducts. in addition,
Microsoft Office 2007 Pro Plus, numerous applications of acoustics to ventilation / exhaust systems in buildings and automobiles use mufflers and acoustic filters to reduce the level of sound propagating down a duct or radiating in the end of a duct. within this laboratory workout you'll investigate the behavior of acoustic waves in a duct with changes in cross-sectional place,
Office 2007 Keygen, facet branches, and resonators. from the procedure you'll observe the behavior of acoustic low-pass, high-pass, and band-stop filters because they are used in a very duct method. ii. the theory of acoustic transmission lines
a rather full theoretical growth of acoustic waveguides,
Microsoft Office 2007 Product Key, transmission lines, and filters could be found in chapters nine & 10 of fundamentals of acoustics, 3rd ed., kinsler, frey, coppens,
Office Home And Student, and sanders, (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 area and shape. simple examples of such structures include hoses, 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 might encounter a change from the acoustic impedance of the duct when the duct (i) opens into free space, (ii) is connected to another section of duct with a different cross-section,
Windows 7 Pro, (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.