摘要:

The performance of a linear array of 2Mtransducers in determining the bearing of a plane‐wave random signal in a background of isotropic random noise is considered. The processing the array is arranged by means of wide‐band phase‐shifting filters and infinite clippers to produce a null response when the array is “on target.” Expressions for the angular uncertainty of the null response are derived, and the filter parameters that minimize this bearing uncertainty are determined. An expression for the minimum bearing uncertainty is also derived for arbitrary signal and noise spectra and also for a case employing well‐known models for signal and noise spectra. The bearing uncertainty of a system with simple filter characteristics determined and compared with the minimum bearing uncertainty.

ISSN:0001-4966    

DOI:10.1121/1.1909478

出版商:Acoustical Society of America    

年代:1965

数据来源: AIP

摘要:

The theory of the howlback of a sound system in an enclosure is discussed. The influence of theQof the enclosure modes on the howlback is considered, and various methods of controlling the howlback are reviewed.

ISSN:0001-4966    

DOI:10.1121/1.1909480

出版商:Acoustical Society of America    

年代:1965

数据来源: AIP

摘要:

A +15‐dB per‐stimulatory shift was noted at 6000 cps in 10 subjects with conductive hearing loss. In another pilot study, median shifts of +12 to +16 dB were noted at 6000 cps in 4 sophisticated listeners under conditions of auditory sensory deprivation.

ISSN:0001-4966    

DOI:10.1121/1.1909482

出版商:Acoustical Society of America    

年代:1965

数据来源: AIP

摘要:

This Letter proposes calibrating audiometers in physical units (SPL) rather than in units referred to stone, more or less, arbitrary audiometric zero.

ISSN:0001-4966    

DOI:10.1121/1.1909484

出版商:Acoustical Society of America    

年代:1965

数据来源: AIP

摘要:

The Long‐time average (100 sec) power spectral densities of speech recorded with a close‐talking microphone are presented for 7 male talkers and 5 female talkers. The average lip to‐microphone distance was approximately58 in.and a breath shield was used. These data were obtained with an analyzer counting of a bank of 54 contiguous Gaussian filters whose scanned output was written on magnetic tape for subsequent computer processing. The processing program obtained the mean‐square amplitude in each filter band and converted it to decibels, with appropriate corrections for filter bandwidth.

ISSN:0001-4966    

DOI:10.1121/1.1909486

出版商:Acoustical Society of America    

年代:1965

数据来源: AIP

摘要:

The use of optical contact as a low‐loss acoustic bond at gigacycle‐per‐second frequencies has been demonstrated. The reflection of 3‐ and 9 Gc sec longitudinal waves from an optical contact bond between two X cut quartz rods has been measured to be of the order of 1% of the incident acoustic power at 1.5°K. Thin X‐cut quartz disks optically contacted to Z‐cut quartz and ruby rods have been used at 1.5°K and found to be about as efficient aa an X‐cut rod.

ISSN:0001-4966    

DOI:10.1121/1.1909488

出版商:Acoustical Society of America    

年代:1965

数据来源: AIP

摘要:

An optical‐contact bond between X‐cut quartz rods reflects about 1% of the incident power for ultrasonic waves of 3 and 9 Gc/sec. The physical origin of the optical‐contact adhesion forces is discussed, along with bond‐thickness estimates. Techniques for making such bonds are described.

ISSN:0001-4966    

DOI:10.1121/1.1909490

出版商:Acoustical Society of America    

年代:1965

数据来源: AIP

摘要:

An ultrasonic‐measurement technique and data‐processing scheme are described in which time intervals are measured between transducer resonance oscillations within the structure of successive unrectified echos rather than between echo leading edges. When plotted against the transducer resonance period, these time intervals determine a family of straight lines that have a single point in common at zero transducer resonance period. It is propo‐ed that the transit time associated with this common point is the true travel time for sound in the medium unperturbed by transducer effects.

ISSN:0001-4966    

DOI:10.1121/1.1909492

出版商:Acoustical Society of America    

年代:1965

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1909494

出版商:Acoustical Society of America    

年代:1965

数据来源: AIP

摘要:

A method is outlined for expressing an average generalized force produced by radiation pressures in a lossfree system in terms of the dependence of impedance, admittance, or scattering matrices on the corresponding generalized coordinate. The results provide a theoretical basis for absolute calibration procedures of intensity‐measuring instruments utilizing radiation pressures.

ISSN:0001-4966    

DOI:10.1121/1.1909502

出版商:Acoustical Society of America    

年代:1965

数据来源: AIP