The measurement of auditory thresholds is ordinarily made by presenting the subject with tones of sufficiently varying intensity to obtain a point where he reports hearing the tone in 50% of the presentations. Although the number of given stimuli is generally not large in routine clinical work, the procedure, nevertheless, is a statistical measurement: The threshold is expressed as the mean of the observations between the intensities of the just-heard tone and the just-not-heard tone. The threshold is not simply the single figure expressed in decibels but an area around this figure with a width of 5 to 15 db., depending mostly on the mode of the stimulation1 and on the reaction time of the subject.
The area between 0 and 100% responses to the stimuli can be charted with all methods of tone presentation. However, the method of limits and the method of constant stimuli are quite time-consuming