In an earlier study [J. Acoust. Soc. Am.54, 334 (1973)] we reported that the subjective quality of music appeared to be unaffected by processing signals through all‐pass phase‐shift networks as used in the SQ quadraphonic matrix encoding system. These conclusions were based on the results of a same/different experiment in which the listeners appeared to be operating at a chance level for a two‐alternative forced‐choice paradigm. They responded with an equal likelihood (50%) of same and different regardless of the nature of the stimulus pairs. Additional experiments have been performed with speech samples using several lists of Harvard PB Sentences. In a same/different experiment, the listeners overwhelmingly judged “same” regardless of conditions. However, in an A‐B‐X experiment, the listeners favored the “B” choice, the one nearest the time to the unknown. Foil conditions of high‐pass filtering, low‐pass filtering, and peak‐clipping were included to verify the performance of the listeners. Correct responses to these conditions were provided except at near discrimination thresholds. One may therefore conclude that such all‐pass networks have no audible effect on subjective quality. In addition, whe presented with a difficult A‐B‐X discrimination task, a significant response bias results from a preference to the stimulus closest in time to the unknown.