The Physical Characteristics of Audition and Dynamical Analysis of the External Ear

This paper discusses some of the characteristics of the ear which have become important in the design and development of telephone apparatus and circuits. The field of audition, bounded by the curves of minimum and maximum loudness as functions of frequency, has been determined for a large number of ears, and the smaller included area most used in speech has been mapped. The nature of these fields in certain cases of abnormal hearing has also been determined and the conditions which must be observed in designing apparatus to satisfactorily relieve deafness are discussed. The sensitivity of the ear is given in terms of the r. m. s. pressure measured by a calibrated condenser transmitter. It is printed out in the appendix that this pressure is not necessarily equal to that which, when applied to the ear drum, would just give rise to the sensation of sound. However, it is the nearest approach to the value of this pressure which can be determined at present, and as the dynamical properties of the ear become more fully known it is pointed out how the relation between the two pressures can be more accurately stated.--Editor.