Speech Sound Processing in the Brain Mike Kilgard University of Texas at Dallas

Hearing and Language

Hearingis in the BRAIN.

? ? ? ? What was that sound?

OR ? ? ? ?

Seconds kHz High Low Seconds kHz High Low

Spectrogram - Example Sounds 8000 Hz Frequency Seconds

Example Speech Sound - “Bad” 8000 Hz Frequency Seconds

“Pad” vs. “Bad” 8000 Hz Frequency Time Seconds

Cash Gash Sash Rash Lash

I wen t to the bea ch and played in the waves

Your brain while hearing words.

Kraus and colleagues, Science 1996 Brain Responses Da vs. Ga Normal Learning Impaired

Processing Speech in Noise

Brain Responses to Speech in Noise

How early are differences in brain responses apparent?

Infant brain responses may predict reading 8 years later. Molfese, Brain & Language, 2000

Can anything be done to improve sound processing?

20±10 vs. 75±20 μV 81±19 vs. 37±20 μV Red Group EnrichedBlue Enriched Environmental Enrichment 22 rats total

EnrichedStandard Environment Physically Alters the Brain!

Training Improves the Brain

Before Training After Training

How exactly does the brain process speech sounds?

“Pad” vs. “Bad” 8000 Hz Frequency Time Seconds

Microelectrode

SadDad High Medium Low Time (milliseconds) vs. is Easy.

RadLad High Medium Low Time (milliseconds) vs. is Hard. 

Dad?Sad?or But rats can’t hear speech. (or can they?)

Rat can distinguish most consonants!!!

Although rats will never learn to talk or read, this new model is providing new insights into the early stages of speech processing and how they might be improved.

Conclusions: 1. Hearing happens in the brain. 2. Fractions of a second matter. 3. The brain doesn’t always do a good job. 5. Our new understanding of neural speech processing may aid development of new therapies. 4. The brain can change. ? ? ? ?

Acknowledgements: Crystal Engineer Claudia Perez Helen Chen