Subject: Speech and bottom-up processes From: "BRUNO H. Repp" <repp(at)lenny.HASKINS.YALE.EDU> Date: Wed, 1 Apr 1998 11:10:28 -0500Although the discussion is beginning to veer away from the original topic, I would like to add some relevant references that modesty forbade me to include with my earlier message. With my dear colleague Neil Todd's messages having relieved me of that inhibition, here I go: Repp, B. H., & Frost, R. (1988). Detectability of words and nonwords in two kinds of noise. Journal of the Acoustical Society of America, 84, 1929-1932. This study was concerned with the detection threshold for the presence of speech in noise, not with the much higher intelligibility threshold. It showed that there is no threshold difference between English words and nonwords, which suggests that the detection process was purely bottom-up. Repp, B. H., Frost, R., & Zsiga, E. (1992). Lexical mediation between sight and sound in speechreading. The Quarterly Journal of Experimental Psychology, 45A, 1-20. There we showed that the detectability of the presence of speech in noise was not influenced by simultaneous visual exposure to matching or nonmatching articulations (lipreading), which again implies an autonomous auditory bottom-up process for speech detection. The lexical status of the stimuli (words or nonwords) affected response bias, but not sensitivity. A similar finding for printed words as the visual stimuli, rather than lipreading, was reported by Frost, R., Repp, B. H., & Katz, L. (1988). Can speech perception be influenced by simultaneous presentation of print? Journal of Memory and Language, 27, 741-755. All three studies provide evidence that the presence of speech can be detected on the basis of acoustic cues long before it is even partially recognized. The detection threshold (70% correct, with 50% being chance) for speech in broadband noise is about -28 dB of S/N ratio, and that in amplitude-modulated (signal-correlated) noise is about -13 dB (Repp & Frost, 1988). Both thresholds are well below the intelligibility thresholds. Bruno H. Repp Haskins Laboratories 270 Crown Street New Haven, CT 06511-6695 Phone: (203) 865-6163 (10:00 a.m. - 6:30 p.m.) FAX: (203) 865-8963 e-mail: repp(at)haskins.yale edu WWW: http://www.haskins.yale.edu/Haskins/STAFF/repp.html