Sonido

Fundamentals of Acoustics

Course No: M02-022 Credit: 2 PDH

J. Paul Guyer, P.E., R.A., Fellow ASCE, Fellow AEI

Continuing Education and Development, Inc. 9 Greyridge Farm Court Stony Point, NY 10980 P: (877) 322-5800 F: (877) 322-4774 info@cedengineering.com

  Fundamentals  of Acoustics     
Guyer Partners
44240 Clubhouse Drive El Macero, CA 95618 (530)7758-6637 jpguyer@pacbell.netJ. Paul Guyer, P.E., R.A.
Paul Guyer is a registered civil engineer, mechanical engineer, fire protection engineer, and architect with over 35 years experience in the design of buildings and related infrastructure. For an additional 9 years he was a senior-level advisor to the California Legislature. He is a graduate of Stanford University and has held numerous national, state and localpositions with the American Society of Civil Engineers and National Society of Professional Engineers.

© J. Paul Guyer 2009

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This course is adapted from the Unified Facilities Criteria of the United States government, which is in the  public domain, has unlimited distribution and is not copyrighted. 

© J. Paul Guyer 2009

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CONTENTS
1. INTRODUCTION 2. DECIBELS 2.1 Definition and use2.2 Decibel addition 2.3 Decibel subtraction 2.4 Decibel averaging 3. SOUND PRESSURE LEVEL 3.1 Definition, sound pressure level 3.2 Definition, reference pressure 3.3 Abbreviations 3.4 Limitations on use of sound pressure level 4. SOUND POWER LEVEL 4.1 Definition, sound power level 4.2 Definition, reference power 4.3 Abbreviations 4.4 Limitations on sound power level data 5. SOUND INTENSITY LEVEL5.1 Definition, sound intensity level 5.2 Definition, reference intensity 5.3 Notation 5.4 Computation of sound power level from intensity level 5.5 Determination of sound intensity 6. VIBRATION LEVELS 6.1 Definition, vibration level
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6.2 Definition, reference vibration 6.3 Abbreviations 7. FREQUENCY 7.1 Frequency unit, hertz 7.2 Discrete frequencies, tonal components7.3 Octave frequency bands 7.4 Octave band levels (1/3) 7.5 A-, B- and C-weighted sound levels 7.6 Calculation of A-weighted sound level 8. TEMPORAL VARIATIONS 9. SPEED OF SOUND AND WAVELENGTH 9.1 Temperature effect 9.2 Wavelength 10. LOUDNESS 10.1 Loudness judgments 10.2 Sons and phons 11. VIBRATION TRANSMISSIBILITY 11.1 Isolation efficiency 12. VIBRATION ISOLATION EFFECTIVENESS 12.1 Staticdeflection of a mounting system 12.2 Natural frequency of a mount 12.3 Application suggestions

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1. INTRODUCTION 1.1 This discussion presents the basic quantities used to describe acoustical properties. For the purposes of the material contained in this document perceptible acoustical sensations can be generally classified into two broad categories, these are: • Sound. Adisturbance in an elastic medium resulting in an audible sensation. Noise is by definition “unwanted sound”. • Vibration. A disturbance in a solid elastic medium which may produce a detectable motion. 1.2 Although this differentiation is useful in presenting acoustical concepts, in reality sound and vibration are often interrelated. That is, sound is often the result of acoustical energy radiationfrom vibrating structures and, sound can force structures to vibrate. Acoustical energy can be completely characterized by the simultaneous determination of three qualities. These are: • • Level or Magnitude. This is a measure of the intensity of the acoustical energy. Frequency or Spectral Content. This is a description of an acoustical energy with respect to frequency composition. • Time orTemporal Variations. This is a description of how the acoustical energy varies with respect to time. 1.3 The subsequent material in this chapter defines the measurement parameters for each of these qualities that are used to evaluate sound and vibration.

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2. DECIBELS The basic unit of level in acoustics is the “decibel” (abbreviated dB). In acoustics, the term “level”...