Brain & Language slides

Speech PerceptionDAY 16 oct 2, 2013Brain & LanguageLING 4110-4890-5110-7960NSCI 4110-4891-6110Harry HowardTulane UniversityCourse organizationThe syllabus, these slides and my recordings are available at http://www.tulane.edu/~howard/LING4110/.If you want to learn more about EEG and neurolinguistics, you are welcome to participate in my lab. This is also a good way to get started on an honor's thesis.The grades are posted to Blackboard.10/02/13Brain & Language, Harry Howard, Tulane University2ReviewSpeech recognition10/02/13Brain & Language, Harry Howard, Tulane University3Linguistic model, Fig. 2.1 p. 3710/02/13Brain & Language, Harry Howard, Tulane University4Discourse modelSyntaxSentence prosodyMorphologyWord prosodySegmental phonologyperceptionAcoustic phonetics Feature extractionSegmental phonologyproductionArticulatory phonetics Speech motor controlINPUTSemanticsSentence levelWord levelSummary of speech recognitionDetails in IngramIt is bottom up.Lexical knowledge of the input would be helpful, but it doesnt make the process much easier.Speech perception involves phonological parsing prior to lexical access.Its output are phonological items/targets.These targets are abstractThey include both acoustic and articulatory information [features].They are normalized across rate, style, and speaker.They may be underspecified.They are discrete. and organized into a hierarchy.It is/may be different from other kinds of auditory perception so it may require special, species-specific neural machinery.10/02/13Brain & Language, Harry Howard, Tulane University5speech PerceptionIngram 610/02/13Brain & Language, Harry Howard, Tulane University6The speech mode hypothesis (SMH)Speed of speech vs. non-speech perceptionThe articulators move at the rate of 8-10 phones per second = 3-4 syllables per second = 2-3 words per second.Early researchers tried to build a machine for reading to the blind [the auditory cipher] which converted each letter to a different non-speech sound and found that no one could understand it at greater than 2-3 sounds per second, which is about a quarter of the rate at which speech is understood.What to do about this inconsistency?10/02/13Brain & Language, Harry Howard, Tulane University7Speech is different!

How so?Speech perception is different from other forms of auditory perception because its targets are linked to a specialized system for their production which we might engage when we listen to speech.Motor theory of speech perceptionSpeech mode hypothesis10/02/13Brain & Language, Harry Howard, Tulane University8http://www.spreadshirt.co.uk/t-shirt-C4408A158250168Can you turn your speech mode off?What is this?

It is this.

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http://www.columbia.edu/~remez/Site/Musical%20Sinewave%20Speech.html9Weak vs. strong versions of SMHWhat does such a distinction mean?The weak speech mode hypothesisWhen we listen to speech, we engage our knowledge of language.The strong speech mode hypothesisWhen we listen to speech, we engage perceptual mechanisms specialized for speech.In the next few slides, we go over the evidence for the latter.10/02/13Brain & Language, Harry Howard, Tulane University10Dichotic listening

Tendencies of right-ear advantage by speech soundNo advantageWeak right-ear advantageStrong right-ear advantagevowelsliquids (l,r), glides (j,w), fricativesstopsthe acoustic cues for vowels do not depend on contextthe acoustic cues for consonants depend on context [see p. 116] > special machinery?10/02/13Brain & Language, Harry Howard, Tulane University11Intermission: Voice onset time (VOT)

10/02/13Brain & Language, Harry Howard, Tulane University12[b][p][p]http://en.wikipedia.org/wiki/File:Vot.svg12Categorical perception

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Chinchillas do this too!

The Clinton-Kennedy continuumhttp://www.sciencedirect.com.libproxy.tulane.edu:2048/science/article/pii/S001002770200104Xhttp://infolific.com/pets/chinchillas/chinchilla-basics/13NEXT TIMEFinish Ingram 6. Go over questions at end of chapter.10/02/13Brain & Language, Harry Howard, Tulane University14