摘要:

A musical instrument is proposed with the following elements: a tone generator capable of reproducing the attack and decay transients and the steady state of the tones of conventional musical instruments with correctly proportioned partials, the frequencies of those associated with one note being integral multiples of a low frequency; keyboards sensitive to the speed with which a key is depressed and the distance to which it is depressed, so that the intensity of each note may be expressively controlled at all times; a unit for the controllable generation of massive choruses from solo voices by producing narrow, complex spectra about each partial; an intensity control unit; environment modification equipment to alter the apparent size of the room within which the music is heard and the apparent size and location of the source, and to distribute and diffuse the sound; a preset unit in which sequences of timbre, vibrato, choral massiveness, environmental characteristics, and other factors may be established before performance and quickly and easily called forth during performance. The features include tones of familiar character and quality, realistic choral effects, expressive touch, environmental control, flexibility, and ease of playing. Numerical results are appended to demonstrate the feasibility of construction.

ISSN:0001-4966    

DOI:10.1121/1.1907726

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

Far‐field noise measurements from model tests of a shielding flap type jet noise suppressor are presented in the form of radiation patterns and frequency spectra. The tests were conducted using a cold air jet issuing from the nozzle in such a manner as to attach to and flow along the surface of a shielding flap. Whereas other proposed noise suppressors provide generally symmetrical noise radiation patterns, the present device skews the pattern in a beneficial way such that large noise reductions are obtained in the downward direction. These large noise reductions are thought to result from both the acoustic shielding of the flap and the benefits of flow attachment.

ISSN:0001-4966    

DOI:10.1121/1.1907727

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

An attempt is made to increase the intelligibility of speech sampled in time (interrupted speech) by filling in the blank spaces with repetitions of the speech samples (reiterated speech). The experiment involves the evaluation of these processes of speech distortion in quiet and in noise with two duty cycles (speech‐time fractions), with various rates of interruption of the speech signal, and with various buildup and decay times in the switching operation. The results indicate that (1) there is little difference between the intelligibility of reiterated speech and interrupted speech in quiet, (2) reiterated speech is more intelligible than interrupted speech in noise if signal measurements are based on instantaneous amplitudes of the speech samples, and (3) buildup and decay has little effect on the intelligibility of interrupted speech when the entire buildup phase is confined to the “on” time of the switching period.

ISSN:0001-4966    

DOI:10.1121/1.1907728

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

Many different instrumental techniques for deriving an energy property of the speech wave have been employed in communication studies. There is as yet, however, no satisfactory method of calculating the loudness of the various types of complex quasi‐periodic sounds that appear as time functions in speech. This paper does not present a method of making such loudness calculations, but suggests that any such method would be inadequate for deriving physical correlates of accent or stress judgments about speech. The study reports volume indicator and instantaneous amplitude observations on sustained vowels produced under various conditions of speech effort, and on vowels produced in CNC syllables in a carrier phrase with stress held constant. The untested theory is proposed that the perception of linguistic stress is based upon judgments of the physiological effort involved in producing vowels. The relative amplitude and spectrum of the vowel provide the chief basis for judgment of the physiological effort.

ISSN:0001-4966    

DOI:10.1121/1.1907729

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

An easily fabricated, bifilar wire strain gauge wound helically about the hilt of an ultrasonic magnetostrictive transducer measures amplitude faithfully and is more convenient than optical methods. Pitfalls in the usual optical method are illustrated and discussed.

ISSN:0001-4966    

DOI:10.1121/1.1907730

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

A simple, rapid, and accurate method of determining temperature coefficient of ultrasonic velocity in liquids is presented. The method is based on a modification of the fixed‐path double‐crystal interferometer. Temperature variation of ultrasonic velocity in a few organic liquids have been studied by employing this method.

ISSN:0001-4966    

DOI:10.1121/1.1907731

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

The usual solutions describing the propagation of continuous waves in solid plates and cylinders fail to predict the observed velocity and attenuation, and secondary signals, in the propagation of a narrow‐band pulse of compressional waves of carrier frequency of the order of 10 Mc/sec. It is shown that all these factors may be accounted for if a slightly different form of solution is chosen, to fit more closely the conditions under which the propagation takes place. Both plates and cylinders are treated theoretically, and methods of obtaining approximate solutions of the modified frequency equations are discussed.The results of this analysis agree closely with those derived by other, less exact methods, which commence with the assumption that the solid medium behaves very similarly to a fluid.The relation of this work to the propagation of pulses at low frequencies is also discussed.A method of analysis similar to that employed here is also necessary to predict experimental results in the propagation of pulses in multilayered wave guides of any configuration, mechanical or electromagnetic.

ISSN:0001-4966    

DOI:10.1121/1.1907732

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

A two‐receiver steerable correlation system intended to process signals from point sources at a large distance from and in a common plane with the receivers will give a predicted source direction which is generally different from the actual source direction when the source distance from the receivers is not large. The exceptions are broadside or end‐fire sources for which the predicted and actual directions are equal. Apart from these cases, the predicted direction is always closer to broadside than the actual direction. Other results include the fact that a given predicted direction corresponds to a source location at any point on a corresponding hyperbolic arc.

ISSN:0001-4966    

DOI:10.1121/1.1907733

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

Two detection systems having multiple inputs each consisting of nonstationary noise and a stationary random signal are analyzed and compared on a signal‐to‐noise ratio basis. In both systems the inputs are divided into two groups and the sum of each group is formed. In the first system the resulting two wave forms are multiplied directly and the product averaged. In the second system the two wave forms are strongly clipped prior to multiplication, forming a polarity‐coincidence correlator. Previous studies have shown the latter system to be slightly inferior for stationary noise. The results of this paper show that the latter system may be quite superior in certain types of nonstationary noise.

ISSN:0001-4966    

DOI:10.1121/1.1907734

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

A siren has been developed which permits the generation of a sound pressure wave with harmonics more than 15 db below the fundamental over a broad frequency range and over a range of power output exceeding 40 db. The large dynamic range was obtained by the use of a shutter which changes the maximum open area of the siren ports and simultaneously alters the time variation of area so that the output signal remains substantially sinusoidal at any shutter position. The shutter can be operated rapidly to provide a means for programed amplitude modulation of the output signal with a minimum of harmonic distortion.

ISSN:0001-4966    

DOI:10.1121/1.1907736

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP