Facilitated auditory detection for speech sounds

If it is well known that knowledge facilitates higher cognitive functions, such as visual andauditory word recognition, little is known about the influence of knowledge on detection,particularly in the auditory modality. Our study tested the influence of phonological and lexicalknowledge on auditory detection. Words, pseudo-words, and complex non-phonological sounds,energetically matched as closely as possible, were presented at a range of presentation levelsfrom sub-threshold to clearly audible. The participants performed a detection task (Experiments1 and 2) that was followed by a two alternative forced-choice recognition task in Experiment2. The results of this second task in Experiment 2 suggest a correct recognition of words inthe absence of detection with a subjective threshold approach. In the detection task of bothexperiments, phonological stimuli (words and pseudo-words) were better detected than nonphonologicalstimuli (complex sounds), presented close to the auditory threshold. This findingsuggests an advantage of speech for signal detection. An additional advantage of words overpseudo-words was observed in Experiment 2, suggesting that lexical knowledge could alsoimprove auditory detection when listeners had to recognize the stimulus in a subsequenttask. Two simulations of detection performance performed on the sound signals confirmedthat the advantage of speech over non-speech processing could not be attributed to energeticdifferences in the stimuli