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Pitch Contour Following Response (PCFR) in Infants

Pitch Contour Following Response (PCFR) in Infants. By: Elizabeth Schnabel Advised By: Dr. Jeng. Overview. Introduction Methods Results Discussion References. Introduction. PCFR – Pitch Contour Following Response A Frequency Following Response (FFR)

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Pitch Contour Following Response (PCFR) in Infants

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  1. Pitch Contour Following Response (PCFR) in Infants By: Elizabeth Schnabel Advised By: Dr. Jeng

  2. Overview • Introduction • Methods • Results • Discussion • References

  3. Introduction • PCFR – Pitch Contour Following Response • A Frequency Following Response (FFR) • Follows the spectral changes in the stimuli.

  4. FFR – Frequency Following Response • Series of sinusoidal peaks – intervals between peaks are phase-locked to the period of the stimulus harmonics • Response from the lower brainstem • Non-invasive insight into the brain’s ability to perceive the Fundamental Frequency of speech. (Moushegian et al., 1973)

  5. Initial Studies Investigated: FFR’s ability to preserve vowel harmonic information. - by presenting a steady state of synthetic approximations of English back vowels. (Krishnan, 2002)

  6. Recent Studies Yi1 Yi2 Yi3 Yi4 hum Investigated: FFR’s ability to follow harmonic tonal change in a stimulus - PCFR • English language tonal change can change the meaning of a phrase. • Tonal languages tonal change can change a single word meaning. Krishnan et al. (2004)

  7. Questions/Hypothesis • (1) Is PCFR able to be recorded from infants? • Hypothesis: PCFR is recordable. • (2) How does infant response compare to adult response? • Hypothesis: Infants will have greater pitch strength to 55dB stimulus • (3) Does the PCFR response get stronger as an infant gets older? • Hypothesis: Infants PCFR response will get stronger an infant gets older.

  8. Methods - Participants • 10 Adults • 7 Infants • Qualifications • Ability to be restful • Normal hearing • Adult: Thresholds normal across all frequencies between 250 and 8000 Hz • Infant: Distortion Product Otoacoustic Emissions - 2000-8000 Hz.

  9. Methods - Stimulus • Voiced Mandarin Chinese syllable • Rising lexical tone: /yi/ meaning ‘aunt’.

  10. Methods- Protocol • One session • Signing consent form • Hearing screening • Electrode/ear tip placement • Restful state achieved • Stimulus and recording started • Two trials of 1200 tokens • Two trials of 1200 control • Clean up and reimbursement forms completed *** Infant_001 completed three session at 1,3,5 months

  11. Methods- Analysis – Q1 • Linear regression between the stimulus and response Fo spectrogram contours was completed to indicate how well the two contours were correlated. • If response was similar to stimulus then we knew it is a PCFR.

  12. Methods- Analysis – Q2 • Autocorrelation – correlating the response to itself • Estimation of pitch period • Estimation of response strength to the pitch (peak to trough amplitude)

  13. Methods – Analysis- Q2 • Analysis of variance (ANOVA) • Compare: • Infant response strength • Adult response strength

  14. Methods – Analysis- Q3 • Plot pitch strength of longitudinal data. • Compare: • Pitch strength • Age in months

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