Log in with Facebook Log in with Google. Remember me on this computer. Enter the email address you signed up with and we'll email you a reset link. Need an account? Click here to sign up. Download Free PDF. Malcolm Crocker. Ramani Ramakrishnan. Bernard Berry. Scott Sommerfeldt. Lawrence Finegold. Alain Muzet. A short summary of this paper. Handbook of Noise and Vibration Control. PART I. Fundamentals of Acoustics and Noise 17 2. Crocker 3. Nelson 4. Sound Propagation in Rooms 52 K. Heinrich Kuttruff 5.
Sound Propagation in the Atmosphere 67 Keith Attenborough 6. Jeremy Astley 8. Boundary Element Modeling D. Herrin, T. Wu, and A. Seybert 9. Morris and Geoffrey M. Lilley Rudenko and Malcolm J. Fundamentals of Vibration General Introduction to Vibration Bjorn A. Petersson Bobrovnitskii Newland Passive Damping Daniel J. Inman Statistical Energy Analysis Jerome E. Manning Nonlinear Vibration Lawrence N. Virgin, Earl H. Human Hearing and Speech Kalveram Yost, Crocker Finegold, Alain G.
Muzet, and Bernard F. Berry Noise-Induced Annoyance Sandford Fidell Hamernik Davis and William J. Murphy Effects of Vibration on People , Michael J.
Griffin Brammer Hearing Protectors Samir N. Gerges and John G. Casali Suter Hearing Conservation Programs John Erdreich Hansen Sound Level Meters George S. Wong Noise Dosimeters Chucri A. Kardous Zaveri Signal Processing Allan G. Piersol Noise and Vibration Measurements Pedro R. Valletta and Malcolm J. Jonasson Sound Intensity Measurements Finn Jacobsen Randall Some machines such as electric motors, fans, indoors and outdoors.
This has applications to indus- trial noise control problems in buildings and to com- D gears, etc. Musical instruments and machines munity noise problems, respectively.
Chapter 2 also TE normally produce several pure tones simultaneously. This elementary system The motion of vibrating systems such as parts of is a useful model for the study of many simple machines, and the variation of sound pressure with vibration problems. Sound waves are composed of the time is often said to be simple harmonic. Let us oscillatory motion of air or water molecules. In air examine what is meant by simple harmonic motion.
PY The simplest form of sound is one-dimensional plane wave propagation. In many practical cases such as in enclosed spaces or outdoors in the environment sound Y propagation in three dimensions must be considered. For more extensive discussions on sound and vibration A A sin wt fundamentals, the reader is referred to more detailed treatments available in several books.
This is 0 A cos wt because very often oscillatory motion, whether it be the vibration of a body or the propagation of a sound wave, is like this idealized case. Next, we introduce the ideas of period, frequency, phase, displacement, velocity, and acceleration. These vibration topics are discussed again at a more advanced Figure 1 Representation of simple harmonic motion by level in Chapters 12, 15, and In Section 5 we projection of the rotating vector A on the X or Y axis.
Suppose OP has a length A, then the Fig. The variation of the projected length is sometimes just called phase. For the case we have on either the X axis or the Y axis with time is said to chosen in Fig. If, instead, represent simple harmonic motion. If we move the origin t seconds to the right in Fig. For mathematical convenience, com- displacement y is said to have gone through one cycle.
If the displace- The number of cycles that occur per second is called ment is written as the frequency f. The use of hertz or Hz is preferable because this has become internationally agreed upon as the unit of frequency. Simple harmonic motion, The time T is known as the period and is usually measured in seconds.
From Figs. Equations 3 , 4 , and 5 are plotted in Fig. Displacement, velocity, and acceleration are really Note, by trigonometric manipulation we can rewrite vector quantities in mathematics; that is, they have Eqs.
Position Note, we could have come to the same conclusions of Mass M and much more quickly if we had used the complex 0 exponential notation. This result, d 2y Eq. If M increases with dt 2 K constant, fn decreases. These are the results we also Let us assume a solution to Eq. Then upon substitution into Eq.
This frequency, mass—spring system just discussed above. Figure 6 Movement of damped simple system. The amplitude of the motion decreases with time unlike that for undamped motion Fig. In the system see Fig. See Chapters 15 and 60 for this case, if the mass in Fig. If the constant of proportionality is R, then the damping oscillation or vibration. See Chapters 15 and The solution of Eq.
By substituting where F is the force amplitude. The motion described by Eq. Figure 8 Forced vibration of damped simple system. It is observed of motion A of the mass is. We shall only consider the piston DMF.
See the top of Fig. As high. During the time T , the large amplitude vibrations can occur with consequent piston has undergone one complete cycle of oscillation. As the piston moves backward and forward, the Substituting this into Eq.
If the gas is compressed into a smaller volume, its pressure increases. The ratio its pressure decreases below atmospheric pressure. The force amplitude transmitted to the machine pressure, p0 , is known as the sound pressure, p, in support base, FB , is seen to be much greater than one, the gas. If these pressure frequency. The results in Eq. Transmitted forces more closely followed in nature. These piston displacement and The propagation of sound may be illustrated by velocity perturbations are superimposed on the much considering gas in a tube with rigid walls and having greater random motion of the gas molecules known as a rigid piston at one end.
The tube is assumed to be the Brownian motion. Since Dark regions in the tube indicate regions of high gas the piston is assumed to vibrate with simple harmonic compression and high positive sound pressure. We call this location, the location of the wave front at the time T.
These results are true for pressure and normal atmospheric pressure. This result is true for all cases of continuous Fig.
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