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THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

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Problems for Chapter 9 2112. Determine the value of the output voltage of a microphone with a sensitivitylevel of −100 dB V/μbar if it is exposed to a sound pressure level of85 dB?3. A sound pressure level reading of 95 dB is taken at the standard conditions of1 atmosphere and 68 ◦ F. What will be the readings at 20 ◦ F and at 95 ◦ F.4. Some laboratory notes indicated that a noise level reading resulted in L eq =95 dB(A) and an SEL of 107 dB(A). How long did this noise level readinglast?5. Assuming a sixth octave analyzer could be made available, determine the firstthree center frequencies after 16 Hz. Also determine the bandwidth.6. Calculate the lower and upper cutoff frequencies and the bandwidth for theoctave band where the center frequencies are, respectively, f 0 = 63 Hz andf 0 = 500 Hz.7. If it is desired to analyze noise in 10 Hz bandwidths with an uncertainty of3%, what must be the necessary averaging time?8. If we are sampling through the FFT process, a signal that ranges from 15 Hzto 30 Hz, what must be the minimum sampling frequency?9. Why is a spectrum analyzer necessary and possibly more useful in dealingwith noise machinery?10. In an FFT analysis, it is desired to have a resolution of 1 Hz. If there are 1000samples in the time series, what must be the minimum frequency samplingrate?

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