Office Professional 2010 acoustic filters.html

many intriguing issues in acoustics entail the propagation of sound in ducts. moreover, many programs of acoustics to ventilation / exhaust systems in buildings and vehicles use mufflers and acoustic filters to reduce the level of noise propagating down a duct or radiating from your finish of the duct. on this laboratory exercising you may discover the habits of acoustic waves within a duct with adjustments in cross-sectional region, side branches,Office Professional 2010, and resonators. inside the method you may observe the conduct of acoustic low-pass, high-pass,Office Professional Plus 2010, and band-stop filters because they are used in a very duct system. ii. the idea of acoustic transmission lines
a somewhat total theoretical growth of acoustic waveguides, transmission lines, and filters may be identified in chapters 9 & 10 of fundamentals of acoustics, 3rd ed., kinsler, frey, coppens, and sanders, (j. wiley & sons,Microsoft Office Standard, 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,Office 2010 Discount, 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,Office 2010 Home And Student Key, 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, (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.