Precedence Effect

The precedence effect, also called the law of the first wavefront, is a binaural psychoacoustic effect concerning how listeners perceive sound reflections and echoes. When two versions of the same sound reach a listener separated by a sufficiently short delay, below the listener's echo threshold, the listener perceives a single auditory event whose apparent location is dominated by whichever sound arrived first. In practice, this means the hearing system gives priority to the location of the first-arriving sound when similar sounds reach the ears in quick succession.