摘要:

The physical conditions for a valid reciprocity free‐field calibration are examined in considerable detail. The expression for the absolute value of the reciprocity parameterJis derived in a general manner. The result shows thatJis actually a transfer admittance relating the volume currentQof the linear, reversible transducer to the pressurePthis unit causes at a certain point in space. The usefulness of this concept in other than free‐field conditions is pointed out. The formula for the sensitivity of the unknown microphone is derived by a method which emphasizes the significance of the physical arrangement, and the limiting conditions are stated. Practical methods for determining the validity of the calibration are suggested.

ISSN:0001-4966    

DOI:10.1121/1.1906545

出版商:Acoustical Society of America    

年代:1949

数据来源: AIP

摘要:

This paper deals with the theory of a class of relaxation mechanisms which may in part account for the absorption of sound in certain solids. The basic postulates of Eyring's theory of absolute reaction rates are applied to the development of general differential equations describing structural‐chemical state changes. The macroscopic effects of transitions between the activated and unactivated states of complexes of atoms are discussed, and the results are applied to the problem of sound absorption and mechanical relaxation due to structural‐chemical changes in soda‐silica glasses. It appears that the transition of alkali ions from holes in the glass lattice into the interstitial space, as in electrolytic conduction, is associated with the acquisition of a certain activation energy, so that the transition probabilities are finite. The process is thus of the nature of a relaxation mechanism which is capable of causing sound absorption. The functional dependence of absorption on frequency predicted by the theory and the predicted functional dependence of the relaxation time on temperature are found to agree with experimental results.

ISSN:0001-4966    

DOI:10.1121/1.1906546

出版商:Acoustical Society of America    

年代:1949

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1906548

出版商:Acoustical Society of America    

年代:1949

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1906550

出版商:Acoustical Society of America    

年代:1949

数据来源: AIP