摘要:

Acoustical measurements and design considerations are discussed for two churches with circular floor plans. One was carefully planned with the acoustics in mind and has proved successful. The other was built with a parabolic concrete dome; a thin sprayed absorbent lining inside the dome was counted on to eliminate sound focusing effects. Echograms taken at several positions inside the church illustrate the resulting severe echo problems.

ISSN:0001-4966    

DOI:10.1121/1.1907809

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

During 1958 a number of corrections were made in the acoustics of Severance Hall designed to lengthen the reverberation time, especially at the higher frequencies, and to project more sound energy from the orchestra to the audience. An entirely new stage shell has been constructed of heavy wood and is tightly enclosed so that a large fraction of the orchestral sound is now directed to the audience. In addition, the shape of the stage shell provides a considerable amount of mixing and blending of the sound, which is a great advantage for the conductor and orchestra. This feature will also be important for the numerous recordings made by the Cleveland Orchestra. The material and design of the heavy wood shell, floor, and risers for the stage, were chosen to achieve a large measure of reflection without undue resonance. Another important modification is the simplification of the proscenium and removal of the heavy curtain which in effect brings the orchestra out into the auditorium to a greater degree than before. Finally, the heavy lined carpeting which was present throughout Severance Hall on all aisles, promenades, and under the seats, has been removed and replaced with an attractive vinyl tile covering of low acoustical absorption. These modifications have made a notable improvement in the quality and intensity of orchestral music in Severance Hall and are highly approved by the concert audience. [R. S. Shankland, J. Acoust. Soc. Am.31, 121 (A) (1959)].

ISSN:0001-4966    

DOI:10.1121/1.1907810

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

The term “acoustoelectronic auditorium” is used to designate an auditorium complex incorporating an integrated design of the room acoustics with the sound reinforcing apparatus. Under these conditions, the acoustic characteristics of the electronic sound system are coordinated and correlated with the acoustics of the enclosure. The features of the acoustoelectronic auditorium are as follows: an enclosure providing a large stage, a low ceiling and a seating capacity of 300; sound reinforcing apparatus consisting of the following features: concealed and fixed stage microphones, concealed and fixed auditorium loudspeakers, and a delay system.

ISSN:0001-4966    

DOI:10.1121/1.1907811

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

This church is unusual in that the basic architectural shape provides the desired acoustical environment, requiring no “applied” sound‐absorbing material. Hearing conditions are highly satisfactory for both speech and music. The reverberation time characteristic discussed along with the “gain” provided by the pulpit canopy.

ISSN:0001-4966    

DOI:10.1121/1.1907812

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

The Fredric R. Mann concert auditorium for an audience of about 2900 and a volume of 750 000 cu ft opened on October 2, 1957. This article covers general design objectives, factors influencing reverberation time (the final value of reverberation time at 500–1000 cps with full occupancy is 1.55 sec), shaping, means for controlling reverberation, echo studies, orchestra enclosure, control of exterior noise, and subjective assessments and recommendations for subsequent changes.The auditorium was designed in accordance with specifications laid down by the Building Committee in September 1951. The design achieved the original objectives. Some changes in the orchestra enclosure and ceiling are desired by the musicians. Acceptance of the hall by audiences has been excellent.

ISSN:0001-4966    

DOI:10.1121/1.1907813

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

Reverberation measurements, made in rooms where the absorption is nonuniformly distributed, usually vary widely from predictions based on the currently employed formulas. Through extensive tests made in a large number of rooms, where distribution of sound absorption varies widely in uniformity, an empirically derived equation is submitted. Photographs of graphic recorder decay curves, showing contrasts in predicted slopes, seem to confirm the validity of the formula. The recorder curves are from field tests. The data submitted are a small portion of an accumulation of measurements, covering several years, in rooms of widely varying volumes, widely varying boundary ratios, and marked dissimilarity in amounts of absorption and ratios of absorption distribution.

ISSN:0001-4966    

DOI:10.1121/1.1907814

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

The transmission loss of very large, single, solid walls is given by the “coincidence‐effect” theory as presented by L. Cremer and others. The results of this theory have been compared with data from field measurements on some typical, masonry walls and are found to be in fairy good agreement. The differences which exist are believed to reflect the inapplicability of the theory to finite sized walls and the imperfection of the sound diffusion in the test rooms. An empirical design technique is presented which agrees more closely with typical field results.The hollow masonry block walls which were studied behave much like solid walls with the same surface weight and bending stiffness. Laboratory techniques are described for measuring the physical constants of these and other materials.Tests made on a typical lightweight aggregate masonry block show that the porosity through the block faces does not greatly reduce the transmission loss. However, painting such a block may increase the bending stiffness of the wall and slightly alter the transmission loss.

ISSN:0001-4966    

DOI:10.1121/1.1907815

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

Formulas pertaining to the calculation of noise in a room produced by a steady source, the measurement of sound power in a reverberant room, and the calculation of reverberation time are reviewed for their appropriateness to engineering use. It is recalled that the simple Sabine reverberation equation can be used without loss of generality provided one associates with a given sound absorbing material a coefficient which is the negative natural logarithm of the energy reflection coefficient; the name Sabine coefficient is tentatively suggested for this quantity. It is noted further that the coefficient usually obtained from tests in a reverberation room is the Sabine coefficient and not truly the sound energy absorption coefficient. A relation is given, between average sound pressure in a room and the power delivered by a source, that does not require averaging absorption coefficients and which is only slightly dependent upon the mean free path. The “Sabine absorption”Sāis more nearly correct (and easier to compute) than the room constant,Sᾱ/(1 −ᾱ) both for the sound‐pressure‐power relationship and reverberation time calculation, whereSis the wall area,āthe average Sabine coefficient, and ᾱ is the average energy absorption coefficient. For sound power level calculations appropriate graphs are provided, showing dependence of intrinsic acoustic impedance and bulk modulus on temperature and barometric pressure or salinity, for air and water, respectively.

ISSN:0001-4966    

DOI:10.1121/1.1907816

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

Following the methods of Lyon, an analysis of the vibratory response of a plate to a random pressure field is given. The pressure correlation of the random field is assumed to have a scale small compared to the plate size, to decay exponentially, and to convect with constant speed over the plate. Two eases are considered, one in which the convection speed is much less than the speed of free flexural waves in the plate, the other in which the convection speed is the same order as the flexural wave speed. The mean square plate displacement is shown to be relatively independent of convection for speeds much less than the flexural wave speed, and to increase significantly for speeds in the order of the flexural wave speed. It is shown that damping is usually, but not always, an effective means of vibration reduction. In the case of convection speeds much smaller than the flexural speed, the use of hysteretic damping for reduction of the displacement response is shown to be limited by the decay of the assumed random pressure field.

ISSN:0001-4966    

DOI:10.1121/1.1907817

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

The diffraction of a plane small amplitude sound wave incident upon a semi‐infinite thin elastic plate is investigated theoretically. The problem is formulated in terms of an integral equation relating the discontinuity in pressure across the diffracting plate to its flexural displacement and the usual fourth order thin plate differential equation governing the flexural motion of the plate when driven by the pressure discontinuity. This pair of coupled equations is then shown to be amenable to solution by the Wiener‐Hopf method. A perturbation procedure, valid in the limit of increasing plate stiffness, is employed to obtain expressions for the sound fields radiated by and transmitted through the plate as well as for the diffracted sound field.

ISSN:0001-4966    

DOI:10.1121/1.1907818

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP