26-Dec-12
Pipes, Resonators, and Filters
26-Dec-12
NTU 522 M3970
1
Resonance in pipes
The fluid in a pipe of cross-sectional area S and length L is driven by a piston at x=0 and that the pipe is termi
18-Dec-12
Cavities and Waveguides
18-Dec-12
NTU 522 M3970
1
Rectangular cavities
A rectangular cavity of dimension X, Y, Z, and its walls are perfectly rigid so that the normal component of the partic
2012/12/9
Reflection and Transmission
9-Dec-12
NTU 522 M3970
1
Changes in media
A plane harmonic wave propagates in x-direction
pe j t = Pe j ( t -k1x )
Pi : the complex pressure amplitude of the inci
2012/12/12
Radiation and Reception
12-Dec-12
NTU 522 M3970
1
Acoustic reciprocity and monopoles
V: space that does not itself contain any sources but bounds them. S: surface of this volume 1 , 2 : vel
Sources of Sound
2012/10/24
NTU 522U5330
1
Sources of sound
Category 1 sources Sources that actively displace fluid in an unsteady manner. It is the rate of change of the rate of fluid volume displace
Spherical and Cylindrical Waves
2012/10/21
NTU 522U5330
1
Specific acoustic impedance
The specific acoustic impedance is
p (unit: rayl) u 1 SI rayl 1Pa S / m z
For plane harmonic waves in free space t
Sound Energy and Intensity
2012/10/17
NTU 522U5330
1
Sound Energy density
The energy transported by acoustic waves is of two forms: (1) The kinetic energy of the moving elements (2) the potential ener
Sound in Fluids
2012/10/2
NTU 522U5330
1
Continuum model of fluid
Fluids connot resist steady applied shear forces. Solid react to steady shear forces by undergoing shear distorsion so that a state o
One-Dimensional Wave Motion
2012/9/12
NTU 522U5330
1
Transverse waves on a string
df y = (T sin ) x + dx - (T sin ) x
(T sin ) df y = (T sin ) x + dx + - (T sin ) x x (T sin ) dx = x
If is small, the
2012/9/10
INTRODUCTION
2012/9/10
NTU 522U5330
1
What is Sound?
ARISTOTLE (384-322 BCE): "The sound emerges when a body moves the air, not by pressing into air a certain form, as some might think, but