Evaluation of maximum-likelihood threshold estimation with tone-in-noise masking.

There has been much recent interest in the use of adaptive psychophysical procedures based on maximum-likelihood estimation (MLE) in order to minimize testing time. The speed and accuracy of MLE was compared to a standard transformed up-down algorithm in a two-interval forced-choice task. Thresholds for detecting a 2 kHz tone in either a broadband or a notched-noise were estimated in three normal-hearing listeners. The transformed up-down algorithm tracked 79% correct with either two, four, six or eight final turnarounds, whereas the MLE procedure tracked 70%, 80% or 90% correct. MLE was always quickest, but with a penalty in increased variability. Use of the MLE procedure to track 70% or 80% correct also resulted in a tendency to overestimate listeners' sensitivity. Reducing the number of turnarounds in the up-down procedure from eight to two reduced the number of trials required by nearly half and resulted in thresholds with similar magnitude and variability to those obtained using MLE to track 90% correct.