Sound waves are generated by the vibration of any solid body in contact with the fluid medium or by...

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Sound waves are generated by the vibration of any solid body in contact with the fluid medium or by vibratory forces acting directly on the fluid, or by the violent motion of the fluid itself. In each case energy is transferred from the source to the fluid. The characteristics of the source generated sound field; reciprocally, the directional properties of the field can be used to shed light on the nature of the source. Any motion of one portion of the fluid medium is transmitted to other parts of the medium; the motion in the frontal region of a sound wave at one instant may be regarded as the source of the subsequent wave motion, farther along in the medium. But in this case the energy of the wave is just being transmitted from one part to another; no new energy being introduced. In this cases mentioned in the first paragraph, however, energy originally not acoustic is being changed to acoustic energy at the source, to be radiated outward and lost to the source. From a point of view of acoustics, a source is a region in space, in contact with the fluid medium, where new acoustic energy is being generated, to be radiated outward as sound waves. We shall devote our attention to the generated sound waves as they move outward from the source .To do so we shall assume that the fluid medium outside the source region is initially uniform and at rest and that the acoustic pressure generated outside the source is small enough so that the first order equations of sound, derived in the preceding chapter are valid in the region outside the source. In this chapter we will discuss the radiation of sound pressure by the simple acoustic source, e.g monopole, dipole, quadrupole etc.
	
Document Preview: CHAPTER IV 
RADIATION BY SIMPLE ACOUSTIC SOURCE 
 XXXXXXXXXXPOINT SOURCE 
Sound waves are generated by the vibration of any solid body in contact with the fluid medium 
or by vibratory forces acting directly on the fluid, or by the violent motion of the fluid itself. In 
each case energy is transferred from the source to the fluid. The characteristics of the source 
generated sound field; reciprocally, the directional properties of the field can be used to shed 
light on the nature of the source. 
Any motion of one portion of the fluid medium is transmitted to other parts of the medium; the 
motion in the frontal region of a sound wave at one instant may be regarded as the source of the 
subsequent wave motion, farther along in the medium. But in this case the energy of the wave is 
just being transmitted from one part to another; no new energy being introduced. In this cases 
mentioned in the first paragraph, however, energy originally not acoustic is being changed to 
acoustic energy at the source, to be radiated outward and lost to the source. From a point of view 
of acoustics, a source is a region in space, in contact with the fluid medium, where new acoustic 
energy is being generated, to be radiated outward as sound waves. 
We shall devote our attention to the generated sound waves as they move outward from the 
source .To do so we shall assume that the fluid medium outside the source region is initially 
uniform and at rest and that the acoustic pressure generated outside the source is small enough so 
that the first order equations of sound, derived in the preceding chapter are valid in the region 
outside the source. 
In this chapter we will discuss the radiation of sound pressure by the simple acoustic source, e.g 
monopole, dipole, quadrupole etc. 
 XXXXXXXXXXMONOPOLE 
A monopole is a source which radiates sound equally 
well in all directions. The simplest example of a 
monopole source would be a sphere whose radius 
alternately expands and contracts...

David · Accepted Answer

Ans. 1 
Page-62 
The sound waves generates due to the disturbance of the fluid medium. The cause of 
disturbance, either solid in contact with fluid or fluid itself. The sound wave always travel from 
one part of medium to another and no any additional energy required after start to flow.

Sound waves are generated by the vibration of any solid body in contact with the fluid medium or by vibratory forces acting directly on the fluid, or by the violent motion of the fluid itself. In each...

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