This course is concerned with how human listeners perceive speech and recognize spoken words. The course is divided into two parts. In the first part, we will review and critically analyze what is current known about speech perception. Our emphasis here will be on several "core" foundational problems in the field including: linearity, invariance, lack of acoustic-phonetic invariance and segmentation, the internal representation of speech, perceptual normalization, units of perceptual analysis, phonological recoding and co-articulation, multi-modal speech perception and cross-language studies of speech perception. We will also consider several theoretical approaches to speech perception including: motor theory, analysis-by-synthesis, feature detectors and interactive-activation theories. In the second part of the course, we will consider several different approaches to the study of spoken word recognition. We are interested in how spoken words are organized in the mental lexicon and how words are accessed and retrieved using acoustic-phonetic information encoded in the speech signal. We will review and critically analyze: Logogen Theory, Lexical Access from Spectra (LAFS), Cohort Theory, Autonomous Search Theory, TRACE, Neighborhood Activation Model (NAM) and PRESENCE. Central to our approach is a concern for frequency, word length and context effects in spoken word recognition and the interaction of multiple knowledge sources underlying robust spoken language comprehension and understanding.