摘要:

The modern systems of communication have been applied to the electronic synthesis of music in the form of the electronic music synthesizer. The electronic music synthesizer is a machine which provides means for producing a tone with any frequency, intensity, growth, duration, decay, portamento, timbre, vibrato, and deviations. If these properties of a tone are specified, the tone can be produced by the synthesizer from a coded record. For implementing the electronic synthesis of music an improved and enlarged electronic music synthesizer Mark II has been developed and built. The new electronic music synthesizer and the use of the new synthesizer by professional musicians will be described.

ISSN:0001-4966    

DOI:10.1121/1.1908043

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

The technique whereby the reciprocity theorem is applied to the determination of the pressure sensitivities of microphones has been modified to improve the reliability and accuracy of the measurements. Sensitivities are measured in terms of the volume of a cavity, the capacity of a fixed condenser, and the variable setting of an accurate potentiometer. Six different pairs of measurements are made instead of three, which is the minimum possible number: this enables check to be made on the internal consistency of each calibration. The accuracy of the measured sensitivities is estimated to be ±0.05 db on an absolute scale and ±0.03 db relative to each other. This technique has been employed to measure the properties of several condenser microphones of each of three well known types over periods ranging from five months to two years. Results are given for their temperature and pressure coefficients, effective volumes due to nonrigidity of their diaphragms and drift with the passing of time.

ISSN:0001-4966    

DOI:10.1121/1.1908045

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

The present work, which deals with acoustic velocity at 500 kc in aqueous solutions of LiOH, NaOH, KOH, andNH4OHand results derived therefrom, follows that which was recently reported concerning solutions of certain sulfates. It was found that the velocityvstemperature curves rise and are displaced toward lower temperatures with increase in concentration. The specific acoustic impedance varies linearly with concentration at 20°C. Adiabatic compressibilities are represented by the empirical 3/2‐power law. Results forNH4OHare at variance with those for the other hydroxides. The relative association declines with increase in concentration in solutions ofNH4OHwhereas it increases for the other hydroxides. From the data the apparent molal compressibilities were computed for the temperature range 15° to 35°C. Based on values of the apparent molal compressibilities at infinite dilution the solvation appears to be about six water molecules per ion.

ISSN:0001-4966    

DOI:10.1121/1.1908047

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

The theory of a new optical method of determining the harmonic structure of progressive ultrasonic waves undergoing finite amplitude distortion is developed using Fourier transforms. The waveform is determined by measurement of the light intensity of all the orders in the diffraction pattern.

ISSN:0001-4966    

DOI:10.1121/1.1908049

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

The suggestion is put forward that the effect of sound waves on heat transfer is dominantly result of the modification of the inner streaming boundary layer which is known to occur when the sound particle displacement amplitudesexceeds in magnitude the acoustic boundary layer thickness δac.

ISSN:0001-4966    

DOI:10.1121/1.1908051

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

An attempt was made to determine the presence of scattering resulting from the nonlinear interaction of two finite‐amplitude sources, operating in water. Experiments were performed with two beams crossed at right angles and also in the nonperpendicular case, A detector crystal, tuned to the summation frequency (13.4 Mc) of the two sources (7.4 Mc and 6.0 Mc), and pivoted about a point above the interaction region, was used to investigate the scattered field. The results indicated no scattered sound above the noise level of the detection system. The lack of scattered sound is in agreement with the theoretical considerations of Westervelt, but is contrary to the predictions of Ingard and Pridmore‐Brown.

ISSN:0001-4966    

DOI:10.1121/1.1908053

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

This paper contains an exact solution within the scope of the bending theory of shells for axisymmetric vibrations of thin shallow elastic spherical shells. Specifically, the solution is applied to an investigation of the natural frequencies of the free axisymmetric vibrations of spherical shell segments with various edge conditions. Comparison drawn with previously known results for transverse vibrations of shallow spherical shells, where the effect of longitudinal inertia is neglected.

ISSN:0001-4966    

DOI:10.1121/1.1908055

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

The notion of a Fourier spectral equivalent of an arbitrary function has been known for a long time in its basic mathematical form. Calculations of these spectral quantities are conventionally based on the Fourier integral. It is not so well known that the Laplace transformation also yields a spectral notion of which the Fourier form is a special case. In addition, vibration engineers have made extensive use in recent years of the concept of a shock spectrum. Simple physical experiments are described which yield direct quantitative spectral values at specified frequencies for any of the three spectra mentioned in the foregoing. These equivalents are useful in assigning physical significance to the quantities under discussion.

ISSN:0001-4966    

DOI:10.1121/1.1908058

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

When a sound beam travels through the sea, it is scattered in all directions by inhomegeneities of various sorts in the sea and on its boundaries. In the backward direction, the aggregate of all the scattered contributions is called “reverberation.” In other directions, the “side scattering” can be studied by using two directional transducers, trained so that the beams cross each other, to measure the sound scattered out of one beam and received on the other. This method was employed in an off‐shore area in the Gulf of Mexico having a particularly uniform bottom. Using two bottomed transducers a mile and a half apart, the intensity of scattering was measured at 22 kc for different angular orientations of the two beams. The measurements were reduced to the coefficient, scattering strength, without requiring either transducer calibrations or direct measurements of transmission loss.The results indicate a bottom scattering strength between −30 and −40 db having no appreciable dependence on angle between the two beams. Within the angular range from the backward direction around to 150° in the forward direction, the scattering appears isotropic. This indicates that isotropic bottom scattering may be safely assumed in applications utilizing separated transmitting and receiving transducers at kilocycle frequencies.

ISSN:0001-4966    

DOI:10.1121/1.1908061

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

An acoustic signal pressure and a noise background are supposed incident upon a general array of hydrophone elements whose individual outputs are combined in a linear manner by means of amplifiers and time delays. Determination is made of the optimum spatial distribution of the hydrophone elements, and also the optimum combination of their outputs, in order to produce in the combined output a maximum value of peak signal in relation to the average noise background. The incident signal is not restricted to be a continuous wave of a single frequency.

ISSN:0001-4966    

DOI:10.1121/1.1908063

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP