Pulsation threshold and simultaneous masking: 2AFC results

Abstract

The pulsation threshold is the signal level at which a series of brief signals appears to be (illusorily) continuous when the intervening intervals are filled with a “masker” (different signal source). It is generally measured by an adjustment or tracking procedure. As a function of the frequency relation of the signal and “masker,” pulsation threshold results are similar in many respects to simultaneous masking patterns. It has been suggested that the two techniques are generally measuring the same aspects of hearing. This was tested by using a 2AFC PEST procedure: pulsation threshold was defined as the signal level for 75% correct discrimination between illusory continuity (signal on only when masker off) and true continuity (signal on at all times). Results were essentially identical to those obtained with a 2AFC PEST simultaneous masking procedure, as well as with a standard tracked pulsation threshold procedure. Given the difficulty which naive subjects often have with finding a stable criterion for pulsation threshold judgments, the 2AFC procedure may be preferable to adjustment tasks. [Work supported by the Deafness Research Foundation.]