Speech Perception DAY 16 – oct 2, 2013

1. Speech PerceptionDAY 16 – oct 2, 2013 Brain & Language LING 4110-4890-5110-7960 NSCI 4110-4891-6110 Harry Howard Tulane University

2. Brain & Language, Harry Howard, Tulane University Course organization • The 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.

3. Brain & Language, Harry Howard, Tulane University Review Speech recognition

4. Brain & Language, Harry Howard, Tulane University Linguistic model, Fig. 2.1 p. 37 Discourse model Semantics Sentence level Syntax Sentence prosody Word level Morphology Word prosody Segmental phonology perception Segmental phonology production Acoustic phonetics Feature extraction Articulatory phonetics Speech motor control INPUT

5. Brain & Language, Harry Howard, Tulane University Summary of speech recognitionDetails in Ingram • It is bottom up. • Lexical knowledge of the input would be helpful, but it doesn’t make the process much easier. • “Speech perception involves phonological parsing prior to lexical access.” • Its output are phonological items/targets. • These targets are abstract • They 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.

6. Brain & Language, Harry Howard, Tulane University speech Perception Ingram §6

7. Brain & Language, Harry Howard, Tulane University The speech mode hypothesis (SMH) • Speed of speech vs. non-speech perception • The 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?

8. Brain & Language, Harry Howard, Tulane University Speech 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 perception • Speech mode hypothesis

9. Brain & Language, Harry Howard, Tulane University Can you turn your speech mode off? What is this? It is this.

10. Brain & Language, Harry Howard, Tulane University Weak vs. strong versions of SMH • What does such a distinction mean? • The weak speech mode hypothesis • When we listen to speech, we engage our knowledge of language. • The strong speech mode hypothesis • When we listen to speech, we engage perceptual mechanisms specialized for speech. • In the next few slides, we go over the evidence for the latter.

11. Brain & Language, Harry Howard, Tulane University Dichotic listening

12. Brain & Language, Harry Howard, Tulane University Intermission: Voice onset time (VOT) [b] [p] [pʰ]

13. Brain & Language, Harry Howard, Tulane University Categorical perception The Clinton-Kennedy continuum Chinchillas do this too!

14. Brain & Language, Harry Howard, Tulane University NEXT TIME Finish Ingram §6. ☞ Go over questions at end of chapter.