We have written this book as part of the underwater acoustics
monograph series
initiated by the Office of Naval Research (ONR), Department of the Navy of the
United States. The ONR objective for this series is publication of in-depth reviews
and analyses of the state of understanding of the physics of sound in selected
areas of undersea research. This monograph presents the theory and practice of
underwater electroacoustic transducers and arrays as developed during the last
half of the twentieth century and into the initial part of the twenty-first century.
We have attempted to present a comprehensive coverage of the subject of transducers
and arrays for underwater sound starting with a brief historical review and
a survey of some of the many mode applications. Descriptions of the six major
types of electroacoustic transducers are presented in a unified way that facilitates
their comparison and explains why some types are better suited than others for
producing and receiving sound in the water. The characteristics of transducers
used as both projectors and hydrophones, and the methods available for predicting
and measuring transducer performance, are presented in detail. The reasons
for combining large numbers of transducers in arrays are explained, and the special
problems that must be considered in such arrays are analyzed. The nonlinear
mechanisms that exist in all transducers are described, and analyses of some of
their most important effects are given. Many different acoustical quantities play
essential roles in the design and performance of electroacoustic transducers and
arrays, and the methods for determining these quantities are presented. Analytical
modeling and understanding is emphasized throughout the book, but it is
also made clear that numerical modeling is now an essential part of transducer
and array design. Non-electroacoustic types of transducers that are used in certain
underwater applications, such as explosive sources, spark sources, hydroacoustic
sources, and optical hydrophones, are not included in this book.
The monograph is organized in a manner that brings the reader quickly to the
main body of results on current transducers and arrays in the first six chapters
with a minimum of background material. The most important basic concepts of
electroacoustic transduction are introduced in Chapter 1, after a brief historical
review and a survey of some of the many applications of transducers and arrays.
Chapter 2 describes and compares the six major types of electroacoustic transducers, presents additional transducer concepts and characteristics, and introduces
the equivalent circuit method of transducer analysis. Chapters 3 through 6
contain the main body of results on mode transducers and arrays. Chapters 3
and 4 cover transducers as projectors, which produce sound, and as hydrophones,
which receive sound, including many details of specific transducer designs as they
are used in current applications. Chapters 5 and 6 explain the benefits of combining
large numbers of transducers in arrays that often contain more than a thousand
individual transducers. These large arrays are necessary in many sonar applications,
but they introduce other problems that are also discussed and analyzed.
The remaining six chapters, 7 through 12, support the earlier chapters and carry
the discussion of concepts and methods into much more detail for those who seek
a deeper understanding of transducer operation. Chapter 7 describes all the principal
methods of transducer modeling, analysis, and design, including an introduction
to the finite element method. Chapter 8 gives further discussion of the most
important transducer characteristics. Chapter 9 describes the principal nonlinear
mechanisms that occur in all the transducer types and presents methods of analyzing
important nonlinear effects such as harmonic distortion. Chapter 10 presents
the basic acoustics necessary for determining those acoustical quantities, such as
directivity pattes and radiation impedance, that are essential to transducer and
array analysis and design. It also includes useful results for such quantities in
several typical cases. Chapter 11 extends the discussion of acoustical quantities
by introducing more advanced methods of analysis that can be applied to more
complicated cases including a brief introduction to numerical methods. Chapter
12 is a summary of the major methods of measurement used for the evaluation
of transducer and array performance. The book ends with an extensive Appendix
containing several types of specific information that can be used in transducer
analysis and design and with a Glossary of Terms.
We have attempted to make this monograph suitable for beginners to lea
from— and for practitioners in the transducer field to lea more from. In addition,
those conceed in any way with undersea research may find useful guidance regarding
applications of transducers and arrays. Although some parts of this book
may be useful to undergraduates, it is written on a graduate level for engineers and
scientists in the fields of electrical engineering, mechanical engineering, physics,
ocean engineering, and acoustical engineering. The book uses SI (MKS) units
in general, but English units are also occasionally used to clarify the relationship
to practical devices.
initiated by the Office of Naval Research (ONR), Department of the Navy of the
United States. The ONR objective for this series is publication of in-depth reviews
and analyses of the state of understanding of the physics of sound in selected
areas of undersea research. This monograph presents the theory and practice of
underwater electroacoustic transducers and arrays as developed during the last
half of the twentieth century and into the initial part of the twenty-first century.
We have attempted to present a comprehensive coverage of the subject of transducers
and arrays for underwater sound starting with a brief historical review and
a survey of some of the many mode applications. Descriptions of the six major
types of electroacoustic transducers are presented in a unified way that facilitates
their comparison and explains why some types are better suited than others for
producing and receiving sound in the water. The characteristics of transducers
used as both projectors and hydrophones, and the methods available for predicting
and measuring transducer performance, are presented in detail. The reasons
for combining large numbers of transducers in arrays are explained, and the special
problems that must be considered in such arrays are analyzed. The nonlinear
mechanisms that exist in all transducers are described, and analyses of some of
their most important effects are given. Many different acoustical quantities play
essential roles in the design and performance of electroacoustic transducers and
arrays, and the methods for determining these quantities are presented. Analytical
modeling and understanding is emphasized throughout the book, but it is
also made clear that numerical modeling is now an essential part of transducer
and array design. Non-electroacoustic types of transducers that are used in certain
underwater applications, such as explosive sources, spark sources, hydroacoustic
sources, and optical hydrophones, are not included in this book.
The monograph is organized in a manner that brings the reader quickly to the
main body of results on current transducers and arrays in the first six chapters
with a minimum of background material. The most important basic concepts of
electroacoustic transduction are introduced in Chapter 1, after a brief historical
review and a survey of some of the many applications of transducers and arrays.
Chapter 2 describes and compares the six major types of electroacoustic transducers, presents additional transducer concepts and characteristics, and introduces
the equivalent circuit method of transducer analysis. Chapters 3 through 6
contain the main body of results on mode transducers and arrays. Chapters 3
and 4 cover transducers as projectors, which produce sound, and as hydrophones,
which receive sound, including many details of specific transducer designs as they
are used in current applications. Chapters 5 and 6 explain the benefits of combining
large numbers of transducers in arrays that often contain more than a thousand
individual transducers. These large arrays are necessary in many sonar applications,
but they introduce other problems that are also discussed and analyzed.
The remaining six chapters, 7 through 12, support the earlier chapters and carry
the discussion of concepts and methods into much more detail for those who seek
a deeper understanding of transducer operation. Chapter 7 describes all the principal
methods of transducer modeling, analysis, and design, including an introduction
to the finite element method. Chapter 8 gives further discussion of the most
important transducer characteristics. Chapter 9 describes the principal nonlinear
mechanisms that occur in all the transducer types and presents methods of analyzing
important nonlinear effects such as harmonic distortion. Chapter 10 presents
the basic acoustics necessary for determining those acoustical quantities, such as
directivity pattes and radiation impedance, that are essential to transducer and
array analysis and design. It also includes useful results for such quantities in
several typical cases. Chapter 11 extends the discussion of acoustical quantities
by introducing more advanced methods of analysis that can be applied to more
complicated cases including a brief introduction to numerical methods. Chapter
12 is a summary of the major methods of measurement used for the evaluation
of transducer and array performance. The book ends with an extensive Appendix
containing several types of specific information that can be used in transducer
analysis and design and with a Glossary of Terms.
We have attempted to make this monograph suitable for beginners to lea
from— and for practitioners in the transducer field to lea more from. In addition,
those conceed in any way with undersea research may find useful guidance regarding
applications of transducers and arrays. Although some parts of this book
may be useful to undergraduates, it is written on a graduate level for engineers and
scientists in the fields of electrical engineering, mechanical engineering, physics,
ocean engineering, and acoustical engineering. The book uses SI (MKS) units
in general, but English units are also occasionally used to clarify the relationship
to practical devices.