Showing papers on "Acoustic source localization published in 1973"
Book•
01 Jan 1973
TL;DR: A Little Dynamics Survey of Wave Types and Characteristics as discussed by the authors : Damping, Impedance and Mobility, Attenuation of Structure-Borne Sound, Sound Radiation from Structures, Generation and Measurement of Structure Borne Sound
Abstract: A Little Dynamics- Survey of Wave Types and Characteristics- Damping- Impedance and Mobility- Attenuation of Structure-Borne Sound- Sound Radiation from Structures- Generation and Measurement of Structure-Borne Sound
473 citations
TL;DR: In this article, the authors used Lighthill's acoustic analogy to study the sound radiated from free flows without dissipation, in the limit as the sound speed tends to infinity.
181 citations
TL;DR: In this paper, an ultrasonic method of measuring the flow of liquids and gases using cross-correlation techniques is described, and the measurement accuracy is independent of the velocity of sound in the fluid.
54 citations
01 Oct 1973
TL;DR: In this article, the spatial distribution of sound source intensities in jets is determined from the sound radiated into the acoustic far field by means of a concave mirror-microphone system.
Abstract: The spatial distribution of sound source intensities in jets is determined from the sound radiated into the acoustic far field by means of a concave mirror-microphone system. The mirror forms an image of the sound sources in a region far enough from the jet so that near field pressure fluctuations can be neglected. The sound intensity in the image is thus closely related to the strength of the actual sound sources in the jet. Results of measurements with jets of Mach numbers 0.7 to 1.9 emanating from circular nozzles and from slot nozzle-flap combinations demonstrate the influence of Mach number and of other parameters upon the sound source distribution.
12 citations
TL;DR: In this paper, a system for measuring sound intensity is described, which can also be used for measuring very low sound levels, and it is shown that the system can be used to measure sound intensity.
Abstract: A system for measuring sound intensity is described which can also be used for measuring very low sound levels.
11 citations
01 Mar 1973
TL;DR: In this paper, the distortion of a wave that is sinusoidal at the source is treated, and the source signal is a pulse band-limited (500 to 3500 Hz) random noise.
Abstract: : As sound pressure increases to 'finite' levels, nonlinear effects usually ignored in acoustics problems become increasingly important. In this paper plane waves propagating through a pipe are considered. In the first section the distortion of a wave that is sinusoidal at the source is treated. In the second section the source signal is a pulse band-limited (500 to 3500 Hz) random noise. In both cases theoretical results are compared with experimental measurements. Extension of the analysis to the more practical case of outdoor propagation is indicated.
7 citations
6 citations
Patent•
01 Jun 1973
TL;DR: In this paper, a sound pick-up for stereo sound reproduction with 90* phase shift between channels in which the armature structure is cylindrical centrally and quadilateral in the remaining parts of its length.
Abstract: A sound pick-up for stereo sound reproduction with 90* phase shift between channels in which the armature structure is cylindrical centrally and quadilateral in the remaining parts of its length.
3 citations
Journal Article•
3 citations
TL;DR: In this paper, a stochastic model was developed to relate the statistics of sound speed fluctuations and bubble density variations as a function of sound frequency in the upper ocean, and the model was compared with ocean experimental data.
Abstract: : Stochastic Models are developed to relate the statistics of sound speed fluctuations and bubble density variations as a function of sound frequency in the upper ocean. These predictions from the stochastic model have been compared with ocean experimental data of sound speed modulation in the frequency range 15 to 150 kHz, and show satisfactory agreement. Future experiments and further modification of this model are discussed. (Author)
3 citations
01 Jun 1973
TL;DR: In this paper, the authors investigated the cancellation effect of the combination of two acoustic fields for the reduction of the discrete tones generated by jet engines, which are essential for jet aircraft to meet present and proposed noise standards.
Abstract: The reduction is discussed of the discrete tones generated by jet engines which is essential for jet aircraft to meet present and proposed noise standards. The discrete tones generated by the blades and vanes propagate in the inlet and exhaust duct in the form of spiraling acoustic waves, or spinning modes. The reduction of these spinning modes by the cancellation effect of the combination of two acoustic fields was investigated. The spinning mode synthesizer provided the means for effective study of this noise reduction scheme. Two sets of electrical-acoustical transducers located in an equally-spaced circular array simultaneously generate a specified spinning mode and the cancelling mode. Analysis of the wave equation for the synthesizer established the optimum cancelling array acoustic parameters for maximum sound pressure level reduction. The parameter dependence of the frequency ranges of propagation of single, specified circumferential modes generated by a single array, and of effective cancellation of the modes generated by two arrays, was determined. Substantial sound pressure level reduction was obtained for modes within these limits.
TL;DR: In this paper, a standing wave acoustic parametric source (SWAPS) was proposed as a small, efficient, low-frequency, nearly omni-directional underwater sound source, where the piston is driven at two neighboring resonance frequencies, the resulting large amplitude primary sound waves mix nonlinearly to produce secondary sound waves.
Abstract: A standing wave acoustic parametric source (SWAPS) has been proposed as a small, efficient, low‐frequency, nearly omni‐directional underwater sound source. SWAPS is envisioned to be a cylindrical tube driven on one end by a piston transducer and terminated on the other end by a thin plug of pressure release material to form a resonant cavity. When the piston is driven at two neighboring resonance frequencies, the resulting large amplitude primary sound waves mix non‐linearly to produce secondary sound waves. The secondary wave at the difference frequency is of low frequency so that it passes easily through the relatively thin tube walls and radiates to the farfield. The farfield radiation at the difference frequency is calculated by use of the virtual source density method. The results are expressed in terms of a quality factor which represents the resonance properties of the cavity. Comparison is made to a traveling wave acoustic parametric source using the same piston transducer.
TL;DR: In this paper, a theory of the reaction of a spin system to a resonant action of an acoustic field and an electromagnetic field is developed, which allows for the coherent properties of the acoustic field that excites the spin system.
Abstract: A theory is developed of the reaction of a spin system to a resonant action of an acoustic field and an electromagnetic field. It is shown that it is important to allow for the coherent properties of the acoustic field that excites the spin system both for the calculation of the line profile of direct acoustic absorption and for the line profile of saturation of paramagnetic resonance by sound. By studying the influence of the acoustic field on the profile of the absorption line of rf power it becomes possible to determine the magnitude and sign of the spin-phonon interaction constant.