A further investigation of echo thresholds for the optimisation of fattening delays

Since the introduction of stereophonic sound systems, mix engineers have developed and employed numerous artificial methods, in order to enhance their productions. A simple yet notable example is the effect commonly known as 'fattening', where a mono signal is cloned, delayed and then panned to the opposite side of the stereo field. The technique can improve a sound's prominence in the mix, by increasing its overall amplitude whilst creating a pseudo-stereo image and is a consequence of a renowned psychoacoustic phenomenon, the 'precedence effect'. This investigation obtained new estimates of echo thresholds and fattening delay times, for a variety of isolated instrumental and vocal recordings, as perceived by a sample population of trained mix engineers. The study concludes that current recommendations for delay times required to create fattening effects should be refined, taking into account not only characteristics of the sound in isolation but also the consequences of temporal and spectral masking, when applied in the context of a multitrack mix.