Showing papers on "Acoustic source localization published in 1974"
TL;DR: Under idealizations about the nature of the path taken by sounds to each of a listener's two ears, and the shape of the listener's head, it is shown that both the azimuth and the range of a sound source can be expressed in terms of the rate at which certain sound stimulus parameters change when sound‐source Azimuth varies.
Abstract: Under idealizations about the nature of the path taken by sounds to each of a listener's two ears, and the shape of the listener's head, it is shown that both the azimuth and the range of a sound source can be expressed in terms of the rate at which certain sound stimulus parameters change when sound‐source azimuth varies. It is further shown that these rates of change can be approximated by a listener if he rotates his head on its vertical axis in ways, and to extents, that are appropriate. The conclusion, then, is that a listener can calculate the azimuth and range of a sound source wholly on the basis of his interaction with the sound stimulus, without any prior knowledge of the sound source. The problem of localization error is discussed, particularly in relation to the extent to which our idealizations depart from reality, and our results are briefly related to those of other researchers in the field of sound‐source localization.
27 citations
TL;DR: In this article, the authors summarized different means and techniques for measuring sound power and pressure averaging in reverberation rooms. But they did not consider the effect of the position of the diffuser vanes on the radiated power.
Abstract: The paper summarizes different means and techniques for measuring sound‐power and ‐pressure averaging in reverberation rooms. Stationary reflectors, properly located in the nearfield of the source and properly oriented with respect to the floor, can contribute considerably to the scattering of the energy radiated by the sound source. The final effect consists of reduction of the dependence of the radiated sound power on the source position. Rotating diffuser vanes are important for determining the sound power radiated at single frequencies. There are three effects: (i) The motion of the vane causes fluctuations of the sound pressure at each point of the chamber and, thus, reduces the dependence of the sound pressure on the microphone location. (ii) The motion of the vane causes a Doppler effect; an originally single‐frequency tone becomes a frequency‐modulated tone. Thus, a single line spectrum becomes a multiline spectrum, which reduces the spatial variations of the sound pressure and also increases the number of room modes excited. (iii) The radiation impedance of the source depends on the instantaneous position of the vane and, thus, its rotation provides averaging of the radiated power. When averaging the sound pressure, different sampling techniques can be used.
20 citations
01 Feb 1974
9 citations
TL;DR: The field-type acoustic wattmeter as mentioned in this paper is a powerful tool for measuring the sound power output of speakers, the noise power of machines in place under operating conditions, the sound absorption of walls, ceilings, and floors, the performance of sound-reproducing systems in rooms, and the sound field in rooms.
Abstract: The field‐type acoustic wattmeter [Olson, U.S. Patent 1,892,644 (1932)] consists of a velocity microphone responding to the particle velocity in a sound wave, a pressure microphone responding to the sound pressure in a sound wave, and an electronic means for combining the outputs of the microphones so the ultimate output of the system indicates the acoustic energy flow in a sound field. The electronic system is all solid state. The field‐type acoustic wattmeter is a useful and powerful tool for measuring the sound power output of loudspeakers, the noise power output of machines in place under operating conditions, the sound absorption of walls, ceilings, and floors, the performance of sound‐reproducing systems in rooms, the sound field in rooms, etc.
8 citations
TL;DR: In this article, the normal mode theory of underwater sound propagation for point multipole sources with arbitrary spatial extent and directionality has been established for the case of a dipole source, which is accomplished by expanding the source in a series of spherical multipole distributions.
Abstract: Normal‐mode theory of underwater sound propagation, which so far has been established only for omnidirectional point sources, is developed here for the case of sources with arbitrary spatial extent and directionality. This is accomplished by expanding the source in a series of spherical multipole distributions. From the Green's function representation, the sound field is then obtained for arbitrary multipolarity of the source, and it simplifies considerably for a point multipole source. Our results are illustrated by a calculation of range‐focusing effects in a channel with parabolic velocity profile using a dipole source.
7 citations
TL;DR: In this paper, the authors measured the volume reverberation and sound velocity for a given spherical particle size, density, and compressibility, and showed that the sound velocity is constant, within the limits of the accuracy of the measuring instrument used.
7 citations
TL;DR: In this article, the velocity of sound and internal pressure of liquid carbonmonoxide, hydrogen sulphide, tetradeuteromethane, hydrogen cyanide, cyanogen, phosphoryl chloride, arsenic trifluoride, iodinemonochloride, and carbondisulphide calculated from the significant structure theory was analyzed.
Abstract: The Significant Structure Theory has been applied to calculate the velocity of sound and internal pressure of liquid carbonmonoxide, hydrogen sulphide, tetradeuteromethane, hydrogen cyanide, cyanogen, arsenic trifluoride, iodine monochloride, phosphoryl chloride, and carbondisulphide. Introduction The Significant Structure Theory of liquids proposed by H E N R Y E Y R I N G and his school [1-4] appears to be the most promising theory of the liquid state. The theory has been applied to evaluate the equilibrium properties of a large number of liquids [5-7]. Further the theory has been applied to evaluate the transport [8], dielectric [9], and surface properties [ 1 0 ] of liquids. Recently D O N G S I K C H O I and M U S H I K J H O N [ 1 1 ] have applied the theory with success to predict the velocity of sound and internal pressure of liquids. In this paper we present the results on velocity of sound and internal pressure of liquid carbonmonoxide, hydrogen sulphide, hydrogen cyanide tetradeuteromethane, cyanogen, phosphoryl chloride, arsenic trifluoride, iodinemonochloride, and carbondisulphide calculated from the Significant Structure Theory. The Significant Structure Theory recognises three structures in the liquid state: (i) molecules possessing oscillational degrees of freedom as in the solid state, (ii) degeneracy acquired due to the availability of additional sites, and (iii) molecules possessing translational degrees of freedom. Assuming random distribution of the moleV V — V cules the relative contributions of solid-like and gas-like molecules are —— and — V V respectively where V is the volume of the liquid and V0 is the volume of the solid-like structures in the liquid state. Thus the partition function for a monatomic molecule such as argon is IV K0 W(K-VO) / = LA/d.,] \" [ / . . , ] \" ( l ) Here / , is the partition function for the solid-like molecules,/gls is the partition function of the gas while / d e g is given by = [1 +
4 citations
TL;DR: In this article, the relative comparison test was used to check the free field conditions and to qualify a given measurement surface for an actual source under test, using a calibrated reference sound source or test sound source in the test site.
Abstract: For determination of sound power of sources by the “method of enveloping measurement surfaces,” the test environment should provide a measurement surface which lies (1) outside the nearfield of the sound source under test and (2) inside a sound field free of undesired sound reflections from room boundaries or reflecting objects near the source. Methods to check the free‐field conditions and to qualify a given measurement surface for an actual source under test are (1) the absolute comparison test using a (small) calibrated reference sound source, (2) the relative comparison test using a small test sound source which radiates broad‐band noise that remains essentially constant during the measurement, and (3) the reverberant test, which requires measurement of reverberation time. Method 3 is only applicable in closed spaces (rooms). Methods 1 and 2 may be used in rooms and outdoors. Methods 1 and 2 require replacing the source under test by the reference sound source or test sound source in the test site. If the source under test cannot be removed, methods 1 and 2 still allow qualification for free‐field conditions, with less accuracy. This paper deals mainly with the relative comparison test (method 2) and gives information about the accuracy of the determination of the environmental corrections factor K under different field conditions.
3 citations
TL;DR: In this paper, a method for determining the sound field in a two-dimensional layer was proposed, which combines the usual method of reflected plane waves with a summation from graphs and makes it comparatively easy to take into account the complex interference pattern due to the transformation of the various waves at the boundaries of the layer and to obtain integral relations for the sound potentials.
1 citations
01 Jan 1974
TL;DR: In this article, the authors deal with Kroebel's method of measuring the sound velocity in liquids particularly in water and seawater, a so called frequency method, using an oscillator with continuous waves.
Abstract: This paper deals with Kroebel's method of measuring the sound velocity in liquids particularly in water and seawater, a so called frequency method, using an oscillator with continuous waves. It is a short report on the work that has been carried out mainly with the aim to develop new high precision instrumentation to improve standard tables of sound velocity data and to get better knowledge about phenomena in the sea causing the build up of fine structured layers and regions of different sound velocities. The accuracy of the values from the absolute sound velocity measuring device in the laboratory has proved to be \pm 1 cm/s to \pm 1,5 cm/s. The sensor developed for free field applications in the ocean using also Kroebel's method has shown a reproducibility of data of about 4 cm/s.