Loudness Tracking and the Staircase Method in the Measurement of Adaptation

The results of several auditory adaptation experiments suggest that binaural interaction, resulting from comparison stimuli presented to the control ear, may affect the amount and rate of adaptation. An attempt was made to evaluate the effects of such interaction with a tracking procedure. The tracking method was found to have 3 shortcomings. Firstly, subjects could predict the direction of attenuation of the comparison signal. Secondly, they could produce an apparently acceptable tracing by responding in a rhythmic fashion or by counting the comparison signals. A third problem appeared to exist in that the tracings moved in the direction of negative adaptation at the start of the adapting period. The double staircase method described by Cornsweet [1962] was employed in an attempt to overcome the disadvantages of tracking. The staircase method was successful in preventing the subjects from predicting the loudness of succeeding comparison stimuli. It also discouraged counting and rhythmic responses but did not eliminate the early negative direction of the adaptation. In addition, it was used to demonstrate that comparison signal duty cycle is a critical factor in the measurement of adaptation.