摘要:

A form of the sonar equations is obtained which is applicable to short transients as well as to pulsed cw waveforms. The equations, in terms of the energy density of the source, are independent of the wave shape of the generated transient and of the echo. They reduce to the ordinary sonar equations for relatively long pulses of constant intensity, and are particularly useful for prediction purposes in applications like explosive echo ranging.

ISSN:0001-4966    

DOI:10.1121/1.1918166

出版商:Acoustical Society of America    

年代:1962

数据来源: AIP

摘要:

Experimental values have been obtained for the thermal noise spectrum of water in the 1.0–2.5 Mc frequency range. The procedure was based on measurement of the radiation resistance of thin‐disk transducers loaded by water. A comparison is made with the theoretical thermal‐noise spectrum of an ideal medium calculated by assigning equipartition energy to the acoustic modes. Agreement to better than 3.6% was found between the experimental values and the theoretical spectrum.

ISSN:0001-4966    

DOI:10.1121/1.1918167

出版商:Acoustical Society of America    

年代:1962

数据来源: AIP

摘要:

The response of a uniform array of point detectors receiving cw signals is computed under the assumption that there are correlations in the fluctuations of the phase of the signals. General formulas are developed for various ranges of correlation. It is shown that the peak response of an array is not appreciably reduced until the magnitude of the fluctuations becomes large. If the fluctuations are strongly correlated over many receiving elements, then the main lobe will be broadened.

ISSN:0001-4966    

DOI:10.1121/1.1918168

出版商:Acoustical Society of America    

年代:1962

数据来源: AIP

摘要:

Auditory nerve responses to short bursts of acoustic noise have been recorded by gross electrodes. For moderate stimulus intensities the amplitude of the response is independent of burst repetition rate for rates below approximately 10/sec. The curve of response amplitude vs rate then decreases except for a small “bump” in the curve near 600/sec. Synchronized responses were detected for repetition rates as high as 3000/sec by an average response computer. These data have been considered in terms of a model that accounts for the overlapping of the response waveforms. In terms of this model, the neural activity decreases monotonically with increasing rate above the rate 10/sec.

ISSN:0001-4966    

DOI:10.1121/1.1918169

出版商:Acoustical Society of America    

年代:1962

数据来源: AIP

摘要:

Rate functions for the amplitude of neural responses are presented as a function of stimulus parameters, such as burst length, intensity, and stimulus power level. The data show that the rate functions depend on all of these parameters in a manner that does not allow for a simple description. Rate functions are also reported for noise bursts in the presence of various levels of steady masking noise. Near visual detection level these rate functions exhibit characteristics that are well accounted for by a model that deals with the overlapping of successive neural responses.

ISSN:0001-4966    

DOI:10.1121/1.1918170

出版商:Acoustical Society of America    

年代:1962

数据来源: AIP

摘要:

A knowledge of pure tone loudness relations is of fundamental interest to all workers in the field of human hearing. Of these relations the pure tone equal‐loudness contours, three sets of which have been independently established, are probably the best known. These three sets of contours have the same general shape but show considerable deviations over parts of the auditory diagram.Making use of the results obtained by different workers and assuming a recently established loudness‐stimulus relation to hold at all frequencies in the audio range, a new set of equal loudness contours has been calculated. A set of curves giving the loudness of equal stimulus contours has also been calculated.

ISSN:0001-4966    

DOI:10.1121/1.1918171

出版商:Acoustical Society of America    

年代:1962

数据来源: AIP

摘要:

A series of experiments measured human ability to discriminate between durations of auditory signals presented in a noise background. Independent variables were the signal voltage, the “base” durationT, and the increment duration ΔT. Separate experiments assessed the effect of each of these on discrimination. A decision‐theoretical model is presented, based on a “counting mechanism,” which operates on impulses generated over the relevant durations. The source of these impulses is assumed to be random. Limitations on performance come from uncertainty regarding the end points of the time interval and from limited memory. The decision processes underlying the model are presented as a general theory of duration discrimination.

ISSN:0001-4966    

DOI:10.1121/1.1918172

出版商:Acoustical Society of America    

年代:1962

数据来源: AIP

摘要:

Nondissipative side‐branch acoustic filters for liquid piping systems are discussed in this report. Simple spring‐mass resonators are used as branch elements. The filters are analyzed as lumped‐parameter systems for short pipe lengths and as distributed‐parameter system for long lengths. One‐, two‐, and three‐section filters are treated and results of tests under both flow and no‐flow conditions are given. Band rejection characteristics are obtained with attenuations up to 40 db for no liquid flow. Under turbulent flow conditions effective attenuation is found to be reduced by noise regeneration.

ISSN:0001-4966    

DOI:10.1121/1.1918173

出版商:Acoustical Society of America    

年代:1962

数据来源: AIP

摘要:

The problems associated with designing effective silencers for suppressing noise from high‐pressure gas blowoffs differ somewhat from those associated with jet aircraft noise suppression because of the high expansion experienced by the gas as it is reduced to atmospheric pressure. Using a combination of aerodynamic and acoustic theory it is possible to calculate the flowing conditions which exist in a silencer and then to correlate these with noise regeneration at the silencer exhaust. Similarly, the effects of silencer internals on attenuating noise introduced into the vessel can be approximated on the basis of field tests and acoustic theory for a wide range of operating parameters. Using the techniques discussed in this paper, both the noise transmitted through a silencer and that regenerated at its exhaust can be approximated, and the over‐all noise reduction characteristics of a silencer design can thereby be anticipated through the use of the analytical techniques or design charts presented.

ISSN:0001-4966    

DOI:10.1121/1.1918174

出版商:Acoustical Society of America    

年代:1962

数据来源: AIP

摘要:

A pulse superposition method of determining ultrasonic wave velocities in materials such as single crystals is shown to be well suited to measurements for pressure and temperature variations. With this method the effect of coupling between transducer and specimen can be made negligibly small. Data are presented for longitudinal waves propagated in theXdirection of quartz and forXYshear waves propagated in theYdirection of quartz. Pressure was varied from 1 atm to 30 000 psi at 25° and −195.8°C. Curves for facilitating the measurement of absolute velocities for a range of specimen impedances are shown in the Appendix.

ISSN:0001-4966    

DOI:10.1121/1.1918175

出版商:Acoustical Society of America    

年代:1962

数据来源: AIP