Fundamentals of acoustics pdf download

Fundamentals of Electroacoustics Author : Fritz A. They are a key part of the modern communication society, helping to transmit information to our ears. A contemporary introduction to the subject, Electroacoustics explains the scientific and engineering principles behind the design of these sound transducers. It also examines the compromises that are necessary when designing transducers for use in the real world.

He uses the concept of electrical circuit analogies to help readers quickly grasp the fundamentals of acoustical and mechanical systems. The book covers both traditional electrodynamic audio and ultrasonic transducers and includes up-to-date material on arrays, planar transducers, loudspeaker enclosure design, and more. To meet the needs of a broad range of readers, the book also includes background material on room acoustics, electrical circuits, and electrical filters.

Electroacoustic theory is explained in an easy-to-read style without resorting to matrix theory. Projects using acoustical tomography systems for exploration of the ocean are presently be ing developed. Each of these systems will allow us to determine the three-di mensional structure of water masses in regions as large as millions of square kilometers.

Mathematical results and physical explanations go hand in hand, and a unique feature of the book is the balance it strikes between time-domain and frequency-domain presentations. Fundamentals of Physical Acoustics is intended for a two-semester, first-year graduate course, but is also suitable for advanced undergraduates. Emphasis on plane waves in the first part of the book keeps the mathematics simple yet accommodates a broad range of topics: propagation, reflection and transmission, normal modes and simple waveguides for rectilinear geometries, horns, inhomogeneous media, and sound absorption and dispersion.

The second part of the book is devoted to a more rigorous development of the wave equation, spherical and cylindrical waves including the more advanced mathematics required , advanced waveguides, baffled piston radiation, diffraction treated in the time domain , and arrays.

However, studying marine life in the ocean is an extremely difficult propo- tion because an ocean environment is not only vast but also opaque to most instruments and can be a hostile environment in which to perform expe- ments and research. The use of acoustics is one way to effectively study animal life in the ocean.

Acoustic energy propagates in water more efficiently than almost any form of energy and can be utilized by animals for a variety of purposes and also by scientists interested in studying their behavior and natural history.

However, underwater acoustics have traditionally been in the domain of physicists, engineers and mathematicians. Studying the natural history of animals is in the domain of biologists and physiologists. Und- standing behavior of animals has traditionally involved psychologists and zoologists.

In short, marine bioacoustics is and will continue to be a diverse discipline involving investigators from a variety of backgrounds, with very different knowledge and skill sets. The inherent inter-disciplinary nature of marine bioacoustics presents a large challenge in writing a single text that would be meaningful to various investigators and students interested in this field.

Pitch: the simplest musical implication of characteristic oscillations : Perceived pitch of a composite sound: rectangle bars ; Small clock chimes ; Bells ; Frequency components of the sounds from a plucked or struck string: guitars and pianos ; Sounds having whole-number frequency ratios ; The pitch of chimes and bells: hints of pattern recognition ; Another pitch assignment phenomenon: the effect of suppressing upper or lower partials ; Pitch assignments and frequency patterns: summary and conclusions 6.

The modes of oscillation of simple and composite systems : Properties of simple oscillators ; A chain of linked oscillators: properties of a single link ; Transverse oscillations of two masses connected by springs ; More than two masses connected by springs ; Characteristic modes of oscillation: a summary -- 7. Introduction to vibration recipes: the plucked string : Combinations of modes: the two-mass chain ; Vibration recipe of a stringlike beaded chain ; The basic recipe of a plucked or struck string -- 8.

Broad hammers and plectra, soft hammers and the stiffness of strings : The equivalence of broad plectra to sets of narrow ones ; The effect of hammer width on the recipe for a struck string ; The effect of impact duration on the recipe for a struck string ; The effect of string stiffness on the excitation of strings ; The upper limits of the vibration recipe: a summary -- 9.

The vibrations of drumheads and soundboards : Unraveling the mode shapes of a glockenspiel bar ; Mode shapes of a rectangular plate having free edges ; The effect of various boundaries ; Adjustment of frequency relations by variations of thickness ; An example: the kettledrum -- Sinusoidally driven oscillations : Excitation of a pendulum by a repetitive force ; Properties of the initial transient motion ; The influence of variable damping on the steady response ; A flute player's unplanned experiment ; Steady excitation of a system having two characteristic modes of vibration ; A summary of the properties of a sinusoidally driven system ; The transfer response of a tin tray ; Some musical implications Room acoustics I: excitation of the modes and the transmission impulses : Sound pressure: a way of describing the characteristic oscillatory modes of room air ; Excitation of room modes by a simple source ; Detection of room modes by a microphone or by the ear: interchangeability of source and detector ; Measured steady-state response: some apparent problems ; Transient response of rooms to sinusoidal excitation ; Response to impulse excitation I: signal delays and reverberation ; Response to impulsive excitation II: reflections and scattering -- Room acoustics II: the listener and the room : Hearing sustained sounds in a room ; The role of early echoes: the precedence effect ; Localization by the ears of sound sources in a room ; Some examples of the interplay between room and ear -- The loudness of single and combined sounds : Thresholds of hearing and pain for a hz sinusoid ; The decibel notation and its application to acoustical signals ; Hearing and pain thresholds at various frequencies ; Variations in the perceive loudness of a single-component sound: sones ; Loudness of combined single-component or narrow-band noise signals having identical or different pitches ; The combined loudness of two or more sinusoids: relationships advertised by beats ; A loudness experiment comparing two saxophone tones ; The sound level meter ; Examples, experiments and questions -- The acoustical phenomena governing the musical relationships of pitch : Heterodyne components: their detection and frequency relationships ; Mechanical origins of the heterodyne components ; The musical tone: special properties of sounds having harmonic components ; Pitch matching: the unison and other special intervals -- Successive tones: reverberations, melodic relationships and musical scales : Reverberation times and the audibility of decaying sounds in a room ; The effect of room reverberation and noise on musical pitch relationships ; Introduction to musical scales ; The function of equal temperament for adjustable-pitch instruments ; Basic scale relations in the music of India ; Other reasons for departures from the special intervals of a scale Some typical sound power levels are given in The decibel dB is the ratio R1 given by Fig.

Then in such cases, the mean create sound pressure levels operating on their own square sound pressures p12 and p22 are additive, and of 80 dB, at a certain point, what is the total sound the total mean square sound pressure at some point pressure level? The total sound pressure level is given by to the case of two pure tones of the same frequency.

Note: For the special case of two pure tones of the of human hearing. The lower boundary in Fig. See Chapter The ear seems to work as phase with each other, then the total sound pressure level a frequency analyzer. We also can make instruments to analyze sound signals into frequency components.

See Fig. For the Example 2 above, the total sound 8. However, at low frequency below about Hz, we cannot hear The center frequency or geometric mean is sound at all well, unless the sound pressure level is quite high. See Chapters 19 and 20 for more details. They have fL fU center frequencies of Figure 16 Typical frequency response of a filter of center frequency fC and upper and lower cutoff frequencies, fU 2.

The center frequencies of one-third octave and fL. L t is sound pressure level from to and Leqn is the short-time average. Li can be a set the night-time A-weighted sound pressure level from of short-time averages for Lp over set periods.

If the to In some countries, separate penalties are made for noise made during evening and night periods. See the hours of and See Eq.

Local Eq. Kinsler, A. Frey, A. Coppens and J. Sanders, Fundamentals of Acoustics, 4th ed. Fahy and J. Walker Eds. Bies and C. Hansen, Engineering Noise 6.