Acoustics : sound fields, transducers and vibration / Leo L. Beranek, Tim Mellow.

Format:

Book

Author/Creator:

Beranek, Leo L., author.

Mellow, Tim J., author.

Language:

English

Subjects (All):

Electro-acoustics.

Sound--Recording and reproducing.

Sound.

Physical Description:

1 online resource (902 pages)

Edition:

Second edition.

Place of Publication:

London, England : Academic Press, [2019]

System Details:

text file

Summary:

Acoustics: Sound Fields, Transducers and Vibration, Second Edition guides readers through the basics of sound fields, the laws governing sound generation, radiation, and propagation, and general terminology. Specific sections cover microphones (electromagnetic, electrostatic, and ribbon), earphones, and horns, loudspeaker enclosures, baffles and transmission lines, miniature applications (e.g. MEMS microphones and micro speakers in tablets and smart phones), sound in enclosures of all sizes, such as school rooms, offices, auditoriums and living rooms, and fluid-structure interaction. Numerical examples and summary charts are given throughout the text to make the material easily applicable to practical design. New to this edition: A chapter on electrostatic loudspeakers A chapter on vibrating surfaces (membranes, plates, and shells) Readers will find this to be a valuable resource for experimenters, acoustical consultants, and to those who anticipate being engineering designers of audio equipment. It will serve as both a text for students in engineering departments and as a valuable reference for practicing engineers. Provides detailed acoustic fundamentals, enabling better understanding of complex design parameters, measurement methods and data Extensive appendices cover frequency-response shapes for loudspeakers, mathematical formulas and conversion factors

Contents:

Front Cover

ACOUSTICS: SOUND FIELDS, TRANSDUCERS AND VIBRATION

Cover Details

Copyright

CONTENTS

PREFACE TO THE SECOND EDITION

PREFACE TO THE FIRST EDITION

ACKNOWLEDGMENTS

One - Introduction and terminology

I: INTRODUCTION

1.1 A LITTLE HISTORY

1.2 WHAT IS SOUND?

1.3 PROPAGATION OF SOUND THROUGH GAS

1.4 MEASURABLE ASPECTS OF SOUND

PART II: TERMINOLOGY

1.5 GENERAL

Acoustic

Acoustical

Imaginary unit

Harmonically varying quantity

Instantaneous value

Root mean square value

1.6 STANDARD INTERNATIONAL (SI) UNITS

1.7 PRESSURE AND DENSITY

Static pressure (P0)

Microbar (μbar)

Instantaneous sound pressure [p(t)]

Effective sound pressure (prms)

Density of air (ρ0)

1.8 SPEED AND VELOCITY

Speed of sound (c)

Instantaneous particle velocity (particle velocity) [u(t)]

Effective particle velocity (urms)

Instantaneous volume velocity [U(t)]

1.9 IMPEDANCE

Acoustic impedance (ZA) (American standard acoustic impedance)

Specific acoustic impedance (Zs)

Mechanical impedance (ZM)

Characteristic impedance (ρ0c)

1.10 INTENSITY, ENERGY DENSITY, AND LEVELS

Sound intensity (I)

Sound energy density (D)

Electric power level or acoustic intensity level

Sound pressure level

Intensity level (IL)

Acoustic power level (PWL)

Sound level

Band power level (PWLn)

Band pressure level (BPLn)

Power spectrum level

Pressure spectrum level

NOTES

Two - The wave equation and solutions

III: THE WAVE EQUATION

2.1 INTRODUCTION

2.2 DERIVATION OF THE WAVE EQUATION

2.2.1 The equation of motion

2.2.2 The gas law

2.2.3 The continuity equation

2.2.4 The wave equation in rectangular coordinates

2.2.5 The wave equation in cylindrical coordinates.

2.2.6 The wave equation in spherical coordinates

2.2.7 General one-dimensional wave equation (Webster's equation) [6]

IV: SOLUTIONS OF THE WAVE EQUATION IN ONE DIMENSION

2.3 GENERAL SOLUTIONS OF THE ONE-DIMENSIONAL WAVE EQUATION

2.3.1 General solution

2.3.2 Steady-state solution

2.4 SOLUTION OF WAVE EQUATION FOR AIR IN A TUBE TERMINATED BY AN IMPEDANCE

Particle velocity

Transmitted and reflected pressures

Impedance

Impedance measurement

Rigid termination (infinite impedance)

Sound pressure

Specific acoustic impedance

2.5 IMPEDANCE OF A CLOSED TUBE USING THE INHOMOGENEOUS WAVE EQUATION

Boundary conditions

Solution of the inhomogeneous wave equation for a closed tube

Impedance of the closed tube

Expansions for cot and csc

2.6 IMPEDANCE OF AN OPEN TUBE USING THE INHOMOGENEOUS WAVE EQUATION

Solution of the inhomogeneous wave equation for an open tube

Impedance of the open tube

Expansion for tan

2.7 SOLUTION OF WAVE EQUATION FOR AIR IN A TUBE FILLED WITH ABSORBENT MATERIAL

2.8 FREELY TRAVELING PLANE WAVE

2.9 FREELY TRAVELING CYLINDRICAL WAVE

2.10 FREELY TRAVELING SPHERICAL WAVE

V: SOLUTIONS OF THE HELMHOLTZ WAVE EQUATION IN THREE DIMENSIONS

2.11 RECTANGULAR COORDINATES

The plane wave equation in x

The plane wave equation in y

The plane wave equation in z

2.12 CYLINDRICAL COORDINATES

The radial equation in w

The azimuthal equation in φ

The axial equation in z

2.13 SPHERICAL COORDINATES

The radial equation in r

The inclination equation in θ

The azimuth equation in φ

Three - Electromechanoacoustical circuits.

VI: MECHANICAL CIRCUITS

3.1 INTRODUCTION

3.2 PHYSICAL AND MATHEMATICAL MEANINGS OF CIRCUIT ELEMENTS

3.3 MECHANICAL ELEMENTS

Mechanical impedance ZM and mechanical admittance YM

Mass MM

Mechanical compliance CM

Mechanical resistance RM and mechanical conductance GM

Mechanical generators

Levers

Simple lever

Floating lever

VII: ACOUSTICAL CIRCUITS

3.4 ACOUSTICAL ELEMENTS

Acoustic mass MA

Acoustic compliance CA

Acoustic resistance RA and acoustic conductance GA

Acoustic generators

Mechanical rotational systems

VIII: TRANSDUCERS

3.5 ELECTROMECHANICAL TRANSDUCERS

Electromagnetic-mechanical transducer

Electrostatic-mechanical transducer

3.6 MECHANOACOUSTIC TRANSDUCER

3.7 EXAMPLES OF TRANSDUCER CALCULATIONS

IX: CIRCUIT THEOREMS, ENERGY, AND POWER

3.8 CONVERSION FROM ADMITTANCE-TYPE ANALOGIES TO IMPEDANCE-TYPE ANALOGIES

3.9 THÉVENIN'S THEOREM

3.10 TRANSDUCER IMPEDANCES

Transmission matrix for an electrical two-port network

Transmission matrix for an electromagnetic-mechanical transducer

Impedance matrix for an electromagnetic-mechanical transducer

Transmission matrix for an electrostatic-mechanical transducer

Impedance matrix for an electrostatic-mechanical transducer

Analogous circuits for the two-port network using z-parameters [12]

Four - Acoustic components

4.1 INTRODUCTION

X: ACOUSTIC ELEMENTS

4.2 ACOUSTIC MASS (INERTANCE)

Tube of medium diameter

4.3 ACOUSTIC COMPLIANCES

Limitations on an acoustic compliance

Series acoustic compliance

4.4 ACOUSTIC RESISTANCES

Tube of small diameter [0.005&lt

l&lt

radius a (in meters)&lt

0.002/f] [1]

Narrow slit [2] [t (in meters)&lt

0.003/f]

4.5 CAVITY WITH HOLES ON OPPOSITE SIDES-MIXED MASS-COMPLIANCE ELEMENT.

4.6 INTERMEDIATE-SIZED DUCTS-MIXED MASS-RESISTANCE ELEMENTS

Medium tube [a (in meters) 0.01/f and a &lt

10/f] [3,4]

Medium slit [t (in meters) 0.02/f and t&lt

20/f] [5]

4.7 PERFORATED SHEET-MIXED MASS-RESISTANCE ELEMENT [A (IN METERS) 0.01/F AND A&lt

10/F] [3,4]

Definition of Q

4.8 ACOUSTIC TRANSFORMERS

Junction of two pipes of different areas

Two pipes of different areas joined by an exponential connector [6]

XI: ELEMENTARY REFLECTION AND RADIATION OF SOUND

4.9 REFLECTION OF A PLANE WAVE FROM A PLANE

4.10 RADIATION FROM A PULSATING SPHERE

Radiation impedance

4.11 RADIATION FROM A MONOPOLE POINT SOURCE (SIMPLE SOURCE)

Pressure and particle velocity

Strength of a point source [6]

Intensity at distance r

4.12 COMBINATION OF POINT SOURCES

Two point sources

Linear array of point sources

4.13 STEERED BEAM-FORMING ARRAY OF POINT SOURCES

4.14 DIPOLE POINT SOURCE (DOUBLET)

Near-field and far-field

4.15 RADIATION FROM AN OSCILLATING SPHERE

Near-field pressure

Far-field pressure

XII: DIRECTIVITY INDEX

4.16 DIRECTIVITY INDEX AND DIRECTIVITY FACTOR

Directivity factor [Q(f)]

Directivity index [DI(f)]

Calculation of Q(f) and DI(f)

XIII: RADIATION IMPEDANCES

4.17 PULSATING SPHERE

4.18 OSCILLATING SPHERE

4.19 PLANE CIRCULAR PISTON IN INFINITE BAFFLE

Approximate analogous circuits

Low- and high-frequency approximations

4.20 PLANE CIRCULAR FREE DISK

4.21 PLANE CIRCULAR PISTON RADIATING FROM ONE SIDE ONLY IN FREE SPACE

XIV: VISCOUS AND THERMAL LOSSES

4.22 SOUND IN LOSSY TUBES

4.23 WAVE EQUATION FOR AN INFINITE LOSSY TUBE

Assumptions

Categories

The momentum conservation equation

Thermal conduction (entropy) and the gas law

Solution of the velocity and temperature radial equations.

Mass conservation and Helmholtz wave equation

Dynamic density

Dynamic compressibility

Wave number and characteristic impedance

4.24 FINITE LOSSY TUBES

A two-port network for a finite tube of any length [13]

A two-port network for a short finite tube

A two-port network for a short finite tube using approximate discrete elements

Regimes for an open-ended tube

Ultra-narrow tube

REFERENCES

Five - Microphones

XV: GENERAL CHARACTERISTICS OF MICROPHONES

5.1 PRESSURE MICROPHONES

5.2 PRESSURE-GRADIENT MICROPHONES

5.3 COMBINATION OF PRESSURE AND PRESSURE-GRADIENT MICROPHONES

XVI: PRESSURE MICROPHONES

5.4 ELECTROMAGNETIC MOVING-COIL MICROPHONE (DYNAMIC MICROPHONE)

General features

Construction

Electro-mechano-acoustical relations

Performance

5.5 ELECTROSTATIC MICROPHONE (CAPACITOR MICROPHONE)

Electromechanical relations

Analogous circuits

Acoustical relations

XVII: PRESSURE-GRADIENT MICROPHONES

5.6 ELECTROMAGNETIC RIBBON MICROPHONES

Analogous circuit

XVIII: COMBINATION MICROPHONES

5.7 ELECTRICAL COMBINATION OF PRESSURE AND PRESSURE-GRADIENT TRANSDUCERS

5.8 ACOUSTICAL COMBINATION OF PRESSURE AND PRESSURE-GRADIENT MICROPHONES

5.9 DUAL-DIAPHRAGM COMBINATION OF PRESSURE AND PRESSURE-GRADIENT MICROPHONES

Omnidirectional performance

Bidirectional performance

Unidirectional performance

Condition for equal sensitivity in all three switch positions

Condition for stability

Six - Electrodynamic loudspeakers

XIX: BASIC THEORY OF ELECTRODYNAMIC LOUDSPEAKERS

6.1 INTRODUCTION

6.2 CONSTRUCTION [2]

6.3 ELECTRO-MECHANO-ACOUSTICAL CIRCUIT

Voice-coil velocity at medium and low frequencies

Voice-coil velocity at low frequencies.

6.4 POWER OUTPUT.

Notes:

Includes bibliographical references and index.

Description based on print version record.

ISBN:

9780128152287

0128152281

OCLC:

1126569977