摘要:

It is difficult to ascertain the absolute loudness of typing noise by objective measurement. However, it may be practical to use such measurement to determine the loudness level difference in a comparison of the sounds from two typewriters. The requirements that must be met by an accurate measurement technique depend on the degree of accuracy required. Information pertaining to the accuracy necessary has been obtained by employment of two loudness matching procedures over a period of several months. The purpose of the tests was to determine the difference in sound pressure level of typing noise necessary to enable a person to identify reliably the louder of two typewriters operated simultaneously in a quiet background. It was found that under the conditions adopted for the investigation, differences in sound pressure level had to be nearly one decibel before they could be recognized 50 percent of the time. Characteristics of typing noise other than pressure level are discussed. The opinion is expressed that these will, in many cases, not cause significant measurement error, and that difference in loudness between typing noises can often be measured with practical accuracy by means of a sound level meter.

ISSN:0001-4966    

DOI:10.1121/1.1917893

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

An electrical speech synthesizer controlled by teletype equipment is described. The basic components of the synthesizer are four simple tuned circuits each of which represents one of the resonances of the human vocal tract. The resonant frequencies of three of the tuned circuits are set by relay circuits that are controlled by data coded on punched tape. The punched tape also controls the intensity and pitch of a buzz generator that excites the variable tuned circuits, and modulates a noise generator that is filtered in various ways to generate fricative or stop consonants. The coded data are read from the tape at about the phonemic rate, with a rate of information transmission of about 35 bits per second. Smoothing circuits are incorporated in the synthesizer to provide smooth formant transitions between sounds. The generation of individual sounds, words, and sentences by the synthesizer is demonstrated.

ISSN:0001-4966    

DOI:10.1121/1.1917900

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

Three loudspeakers, equidistant from the subject, one in front and one at 40° to each side, when employed in pairs with the speakers of the pair in phase, provided three phantom sources to be localized. This method of presenting the stimulus brings about a different relationship between the stimulus factors for localization, time and intensity, from what occurs with a single source. The results show that in the low‐frequency region from 500 to 1200 cps localization is dependent principally upon interaural time differences. In the range from 1200 to 1750 cps, time‐ and intensity‐differences can combine to produce large bias errors. At frequencies from 2000 to 5000 cps, individual differences in sensitivity and other factors appear to destroy any simple relationship between interaural intensity and localization.

ISSN:0001-4966    

DOI:10.1121/1.1917908

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

The acoustical effects achieved and the techniques used in the radiation of organ tone are quite different from the conventional effects and practices of public‐address sound systems. For the latter, point‐source radiation with high uniform directivity and a minimum of reverberation are sought, in general, for the creation of the illusion of “presence” of the original sound source. However, in organ music the sound sources are distributed in space. Individually the sources are quite complex in their directional pattern, and collectively their sound distribution is diffuse. This is especially true in those typical cases where the tone sources are enclosed in an organ chamber or box or are installed in a highly reverberant environment. Another distinctive feature of organ tone radiation systems is the relative importance of the octave below 60 cps, a frequency range frequently neglected even in sound systems designed for general musical purposes. In this paper the design principles of organ tone chambers and the types of organ tone cabinets in use are reviewed. Organ installation principles and examples of their application are given. The implication of these principles with regard to optimum reverberation for church auditoriums is discussed.

ISSN:0001-4966    

DOI:10.1121/1.1917913

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

This investigation stemmed from an attempt to explain the nature of the dispersion occurring when a beam of light is reflected from a test record. Examination through color filters revealed the existence of two distinct patterns of lines which the author has termed theAandBlines.A‐lines are identified with the frequency andBlines with the amplitude of the recorded sound.B‐line patterns can be readily related to the modulation velocity and lead to an accurate determination of the recorded velocity characteristic of a test record. Characteristics by conventional light patterns are found to be in error owing to diffraction of light at the edges of the pattern. This error is estimated by subtracting the modulation velocity byB‐line patterns from that determined by conventional light pattern techniques, and it is found to be approximately equal to the calculated diffraction error from assumed triangular wavelets. Calibrations of representative test records byB‐line patterns are in much better agreement than those by conventional light patterns with the calibrations obtained by the variable‐speed turn‐table technique, especially when the latter are corrected by the estimated amount of error owing to the elastic deformation of the modulated groove by the pickup load.

ISSN:0001-4966    

DOI:10.1121/1.1917917

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

Measurement and comparison of mating calls in anuran amphibians is desirable because differences in call are important mechanisms that help to prevent free interbreeding of closely related species. Calls have been recorded and analyzed on a Sona‐Graph for some 27 species representing 10 genera of amphibians. Calls vary individually in natural populations; they vary geographically within species populations; and they differ between species. Closely related species which occur together differ conspicuously from one another in at least one or two variables, such as emphasized frequency or duration.

ISSN:0001-4966    

DOI:10.1121/1.1917922

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

When a battery is connected between two electrodes immersed in an electrolyte, the phenomenon known as polarization occurs. This polarization limits the electric current which will flow through the electrolyte for a given potential difference. As is well known to those familiar with the method of chemical analysis known as polarography, the degree of polarization and consequent current flow through the electrolyte is a function not only of the chemical composition of the electrolyte, but also of the amount of agitation, either thermal or mechanical, which the electrolyte experiences. In this paper, an apparatus is described which allows investigation of the flow patterns resulting when low‐frequency sound in liquid passes through small orifices.

ISSN:0001-4966    

DOI:10.1121/1.1917926

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP