Diagnostic Precision of Open-Set Versus Closed-Set Word Recognition Testing

Purpose: The aim of the study was to examine the precision of forced-choice (closed-set) and open-ended (open-set)word recognition (WR) tasks for identifying a change inhearing.Method: WR performance for closed-set (4 and 6 choices)and open-set tasks was obtained from 70 listeners withnormal hearing. Speech recognition was degraded bypresenting monosyllabic words in noise (−8, −4, 0, and 4signal-to-noise ratios) or processed by a sine wave vocoder(2, 4, 6, and 8 channels).Results: The 2 degraded speech understanding conditionsyielded similarly shaped, monotonically increasing psychometricfunctions with the closed-set tasks having shallower slopesand higher scores than the open-set task for the samelistening condition. Fitted psychometric functions to theaverage data were the input to a computer simulationconducted to assess the ability of each task to identify achange in hearing. Individual data were also analyzed using95% confidence intervals for significant changes in scoresfor words and phonemes. These analyses found thefollowing for the most to least efficient condition: open-set(phoneme), open-set (word), closed-set (6 choices), andclosed-set (4 choices).Conclusions: Closed-set WR testing has distinct advantagesfor implementation, but its poorer precision for identifying achange than open-set WR testing must be considered.