An acoustic waveguide is a section of the medium that is limited in one or two directions by walls or other media. Due to this, the discrepancy of the waves to the parties decreases, as a result, the sound spreads along a plot with a smaller weakening than in an unlimited homogeneous environment.

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Artificial acoustic waveguides are usually trumpets, limited soundproof walls (for example, organ pipes, ventilation channels, tunnels). Natural acoustic waveguides are usually layers of the medium. For example, for low sound frequencies, the ocean is a waveguide in the form of a layer of water, which is limited on one side with soil, and on the other hand, the free surface of the water. The acoustic waveguide is formed by vertical layered inhomogeneity of the medium (underwater audio channel in the ocean): Waves crossing under low layer angles, in which the speed of sound has the minimum value, wrapped back as a result of refraction in adjacent layers with a greater sound speed, as if reflecting From these layers (see Hydroacousti). Unlike pipes where the sound spreads straightforwardly (along the axis of the pipe), the sound in the layer can also be distributed as cylindrically diverging or converging waves.

Properties:

In acoustic waveguides with a layered-inhomogeneous medium, there are also discrete sets of normal waves with similar properties. With a layered inhomogeneity of the medium that fills the waveguide, the standing wave in the transverse direction will no longer be sinusoidal, but normal waves can still be numbered by the number of nodal lines in cross section. The dispersion properties of natural acoustic waveguides are usually significantly different from the dispersion properties of homogeneous waveguides.

Solid-state acoustic waveguides are usually limited to free boundaries (rods, plates). Normal waves in such acoustic waveguides are formed both by the shear waves of the horizontal (parallel boundary of the polarization), and jointly by propagating longitudinal and shear waves of vertical polarization converted to each other during reflections on the borders. A set of such normal waves is richer than in liquid acoustic waveguides. In particular, they are possible normal waves with complex wave numbers.

An acoustic waveguide

The segment of the medium limited in one or two directions by walls or other media, resulting in or decreases the discrepancy of the waves to the parties, so that the propagation of sound along the site occurs with a weakening of less than in an unlimited homogeneous environment. Artificial V. A. - Usually pipes limited by soundproof walls (eg, fans. Channels, tunnels). Natural V. A. - usually layers of the medium. For example, for low sound frequencies, the ocean is a waveguide in the form of a layer of water bounded on one side with soil, and on the other - the free surface of the water. V. A. It can be formed by layered inhomogeneity of the medium in a version. The direction (eg, underwater sound. Canal in the ocean): Waves crossing the layer, in a rotary speed of sound has mines. The value under low angles, turn to it back as a result of refraction in adjacent layers with a greater speed of sound, as if reflecting from these layers (see hydroacousti). In contrast to pipes, in which sound can only be distributed along one straight line (axis of the pipe), the sound in the layer can also be distributed as a cylindrically divergent wave.

Any sound. Field inside V. A. It can be represented as a superposition of normal waves. In the simplest case of two-dimensional sound propagation in a homogeneous layer or in the pipe is snug. cross sections. The wave is a harmonic wave running along V. A. And standing in the transverse direction. At this frequency in V. A. (as in the radio wavewoman) there may be an infinite disc. Set of rules. Waves, differing phase velocity and the number of nodal lines sound. Fields in the transverse direction: each norm. The wave is attributed to the number, equal number These nodes. For every rules. Waves I have its own frequency, called. Critical WKR, K-paradium grows with an increase in the wave room. Below this frequency of the norm. The wave does not apply, but turns into a simphase oscillation with an amplitude varying along the waveguide according to the exponential law. The exception is represented by V. A. With absolutely rigid or elastic walls: they are zero norms. Wave, criticism. Frequency to-swarm WKR \u003d 0. can run at any frequency.

In case of three-dimensional propagation of sound in the pipe can also exist an infinite disc. Set of rules. waves. They differ from the rules. Waves with two-dimensional distribution in that they have a standing wave in cross section has one, but two families of nodal lines. In the pipe right. section nodal lines parallel to one and another pair of opposite walls: in round trumpet Nodal lines - concentric. Circle and diameters. Each rules. A wave at three-dimensional distribution receives a double number indicating the numbers of nodal lines of one and another family. These norms. Waves also have their criticism. Frequencies below to-ry, as in a two-dimensional case, distribution stops.

In V. A. Any harmonic. The wave can be represented in the form of superposition norms. Waves of different numbers of the same frequency. At a given frequency, only a finite number of rules is distributed. waves of lower numbers. Therefore, the structure of the distribution sound. Fields along the waveguide corresponding to the high numbers of the norm. Waves along the waveguide is not transmitted. Norm. Waves characterized means. Speed \u200b\u200bdispersion. In V. A. Phase speed. The waves of the zero number is always greater, and group speed is less than the speed of sound with in nezrans. medium; With increasing frequency, the first decreases, and the second is growing, and both strive asymptotically to with. The exception is zero norms. Wave in V. A.. with absolutely rigid walls; In this case, this is an ordinary illegal flat wave, running unchanged with any form of a profile, as in nezrans. Medium.

In arts. V. A. with a layered inhomogeneous medium and in nature. V. A. There may also be infinite discras. Sets of norms. Waves with similar dies. For example, with a layered inhomogeneity of the medium that fills the waveguide, the standing wave in the transverse direction will not be sinusoidal, but norms. The waves can still be numbered by the number of nodal lines in cross section. Disperse. St. Nat. V. A. Typically differ significantly from the dispersion. SV-in homogeneous waveguides.

Solid V. A. Usually limited to free boundaries (rods, plates). Norm. Waves in solid V. A. Educated either only shear waves horizon. polarization, or jointly propagating longitudinal and shear waves of a quiliency. polarization converted to each other when reflections on the borders. In the Ultrasound Technology Technology V. A. Naz. Also, any device (rods, hubs) for transmitting oscillations. Energy on some distance from the source or for the introduction of oscillations. Energy in K.L. Wednesday.

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• - Layer in a troposphere, favorable for distribution of radio waves ...

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• - Canal for the spread of waves. Distinguish acoustic. B. In the form of a pipe or rod, radio waven supply, sairty water, etc. V. Usually used for directional transmission of signals or energy ...

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• - Channel having sharp boundaries according to which waves apply. For sound waves - pipe, rod or string ...

  Great Soviet Encyclopedia

• - Channel for which acoustic energy is transmitted ...

  Great Soviet Encyclopedia

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• - Channel having sharp boundaries along which electromagnetic or sound waves apply. A metal pipe can serve as a radio film, a dielectric rod, and so on ....

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• -; MN. Wave / dy, p ....

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• - waveguide m. The device in the form of a canal, pipes, rod, etc., intended for the propagation of sound or electromagnetic waves ...

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• - ...

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• - Waves "...

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  Shape words

• - SUB., Number of synonyms: 1 radio ...

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"Wavewood acoustic" in books

Acoustic wind

Acoustic emitter

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Acoustic wavewoman - The area of \u200b\u200bthe medium, limited in one or two directions by walls or other media, resulting in or decreases the discrepancy of waves to the parties, so the spread of sound along the site occurs with a smaller weakening, rather than in an unlimited homogeneous environment.

Types

Artificial acoustic waveguides - usually pipes limited by soundproof walls (for example, organ pipes, ventilation channels, tunnels).

Natural acoustic waveguides - usually layers of medium: for example, for low sound frequencies, the ocean is a waveguide in the form of a water layer bounded on one side with soil, and on the other - the free surface of the water. An acoustic waveguide can also be formed by vertical layered inhomogeneity of the medium (for example, underwater sound channel in the ocean): Waves crossing under low corners with a layer in which the speed of sound has a minimal value, wrapped back as a result of refraction in adjacent layers with a greater sound speed. , as if reflecting from these layers (see hydroacousti). In contrast to pipes in which the sound propagates straightforwardly (along the axis of the pipe), the sound in the layer may also be distributed as cylindrically divergent or converging waves.

Properties

The only form of waves propagating in acoustic waveguides without changing its structure is normal waves (mods). In the simplest case of sound propagation in a homogeneous non-hardware, the filling layer or rectangular cross section, the normal wave is a harmonic wave, running (homogeneous normal wave) or an exponentially decaying (inhomogeneous normal wave) along the waveguide, and a sinusoidal standing wave in the transverse direction. At a given frequency, normal waves form an infinite discrete set of waves, differing phase velocity and the number of nodal audio field lines in the transverse direction: each normal wave is attributed to the number equal to the number of these lines.

In an acoustic waveguide with a layered-inhomogeneous medium, both in artificial and natural, also there are discrete sets of normal waves with similar properties. With a layered inhomogeneity of the medium that fills the waveguide, the standing wave in the transverse direction will no longer be sinusoidal, but normal waves can still be numbered by the number of nodal lines in cross section. The dispersion properties of natural acoustic waveguides are usually significantly different from the dispersion properties of homogeneous waveguides.

Solid-state acoustic waveguides are usually limited to free boundaries (rods, plates). Normal waves in such acoustic waveguides are formed both by the shear waves of the horizontal (parallel boundary of the polarization), and jointly by propagating longitudinal and shear waves of vertical polarization converted to each other during reflections on the borders. A set of such normal waves is richer than in liquid acoustic waveguides. In particular, they are possible normal waves with complex wave numbers.

In ultrasonic technology, all sorts of devices (rods, hubs) are also called solid-state acoustic waveguides to transmit oscillatory energy to a certain distance from the source or to introduce oscillatory energy into any environment.

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Literature

• Varlamov A. A., Malyarovsky A. I. // Kvant. - 1985. - № 2. - P. 13-18.

Excerpt characterizing acoustic waveguide

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An acoustic waveguide - section of the medium, limited in one or two directions by walls or other environments, resulting in or decreased by the discrepancy of waves to the parties, so the spread of sound along the site occurs with a weakening smaller than in nezrans. Uniform medium. Arts. V. A. - Usually pipes, limited by soundproof walls (eg, organ pipes, fans. Channels, tunnels). Nat. V. A. - Usually layers of the medium: for example, for low sound frequencies, the ocean is in the form of a water layer, limited on one side with soil, and on the other - the free surface of the water. V. A. A quantity may also be formed. Layered inhomogeneity of the medium (eg, underwater sound channel in the ocean): Waves crossing under low corners layer, in K-ROM has a minimum. The value is wrapped in back as a result of refraction in adjacent layers with a greater speed of sound, as if reflecting from these layers (see Hydroacoustics). In contrast to the pipes, in which the sound applies straightforwardly (along the axis of the pipe), the sound in the layer can also be distributed as cylindrically diverging or converging waves.

Unity. The form of waves propagating in V. A. unchanged its structure - normal waves (Fashion). In the simplest case of sound propagation in a homogeneous non-hardware, filling layer or a rectangular cross section, a normal wave is a harmonic wave running (homogeneous norms) or exponentially decaying (inhomogeneous norms. Wave) along the waveguide, and a sinusoidal standing wave in the transverse direction . At a given frequency, normal waves form an infinite discrete set of waves, differing phase velocity and the number of nodal audio field lines in the transverse direction: each normal wave is attributed to the number equal to the number of these lines. The propagation of a normal wave in V. A. Characterized additional. speed dispersion; The exception is only normal waves of the zero number: their speed is exactly equal to the speed of sound and the dispersion depends only on the properties of the medium fill in V. A. Phase speed of normal waves of the nonzero number are always greater, and less than sound speed from in nezrange. Medium. With increasing frequency, the first decreases, and the second increases and both strive asymptotically to C. For each normal wave number i. There is its own frequency, called. Critical, the bigger, the higher the wave number. Below this frequency, this normal wave and all the waves of the highest numbers do not apply, but are oscillations with an amplitude varying along the waveguide by exponentials. law. The exception is again representing a zero normal wave in V. A. With absolutely rigid or elastic walls: this wave can run at any frequency, since it. In V. A. Any free harmonic. The wave can be represented as a superposition of normal waves of different numbers of the same frequency. At a given frequency, only a finite number of normal waves of lower numbers is distributed.

In V. A. With a layered inhomogeneous medium, both in artificial and natural, also there are discrete sets of normal waves with similar properties. With a layered inhomogeneity of the medium filling the waveguide, in the transverse direction will not be sinusoidal in the transverse direction, but normal waves can still be numbered by the number of nodal lines in cross section. Dispersion properties of nature. V. A. Typically differ significantly from the dispersion properties of homogeneous waveguides.

Solid-state V. A. Usually limited to free boundaries (rods, plates). Normal waves in such V. A. Educated both shear waves of the horizontal (parallel border of the section), and jointly by propagating longitudinal and shear waves of a version. polarization converted to each other when reflections on the borders. A set of such normal waves is richer than in liquid V. A. In particular, they are possible normal waves with complex wave numbers. In Uz-technology solid-state V. A. Naz. Also all sorts of devices (rods, hubs) for transmission of oscillations. Energy on some distance from the source or for the introduction of oscillations. Energy in k - l. Wednesday.

LIT: Brehovsky L. M., Waves in layered media, 2 ed., M., 1973; Rzhevkin S. H., lecture course on sound theory, M., 1960, ch. 6; Physical acoustics, ed. W. Masona, Per. from English, vol. 1, h. A, M., 1966; Isakovich M. A., Total acoustics, M., 1973. M. A. Isakovich.

Acoustic wavewoman - The area of \u200b\u200bthe medium, limited in one or two directions by walls or other media, resulting in or decreases the discrepancy of waves to the parties, so the spread of sound along the site occurs with a smaller weakening, rather than in an unlimited homogeneous environment.

Types

Artificial acoustic waveguides - usually pipes limited by soundproof walls (for example, organ pipes, ventilation channels, tunnels).

Natural acoustic waveguides - usually layers of medium: for example, for low sound frequencies, the ocean is a waveguide in the form of a water layer bounded on one side with soil, and on the other - the free surface of the water. An acoustic waveguide can also be formed by vertical layered inhomogeneity of the medium (for example, underwater sound channel in the ocean): Waves crossing under low corners with a layer in which the speed of sound has a minimal value, wrapped back as a result of refraction in adjacent layers with a greater sound speed. , as if reflecting from these layers (see hydroacousti). In contrast to pipes in which the sound propagates straightforwardly (along the axis of the pipe), the sound in the layer may also be distributed as cylindrically divergent or converging waves.

Properties

The only form of waves propagating in acoustic waveguides without changing its structure is normal waves (mods). In the simplest case of sound propagation in a homogeneous non-hardware, the filling layer or rectangular cross section, the normal wave is a harmonic wave, running (homogeneous normal wave) or an exponentially decaying (inhomogeneous normal wave) along the waveguide, and a sinusoidal standing wave in the transverse direction. At a given frequency, normal waves form an infinite discrete set of waves, differing phase velocity and the number of nodal audio field lines in the transverse direction: each normal wave is attributed to the number equal to the number of these lines.

In an acoustic waveguide with a layered-inhomogeneous medium, both in artificial and natural, also there are discrete sets of normal waves with similar properties. With a layered inhomogeneity of the medium that fills the waveguide, the standing wave in the transverse direction will no longer be sinusoidal, but normal waves can still be numbered by the number of nodal lines in cross section. The dispersion properties of natural acoustic waveguides are usually significantly different from the dispersion properties of homogeneous waveguides.

Solid-state acoustic waveguides are usually limited to free boundaries (rods, plates). Normal waves in such acoustic waveguides are formed both by the shear waves of the horizontal (parallel boundary of the polarization), and jointly by propagating longitudinal and shear waves of vertical polarization converted to each other during reflections on the borders. A set of such normal waves is richer than in liquid acoustic waveguides. In particular, they are possible normal waves with complex wave numbers.

In ultrasonic technology, all sorts of devices (rods, hubs) are also called solid-state acoustic waveguides to transmit oscillatory energy to a certain distance from the source or to introduce oscillatory energy into any environment.