Human Frequency-Following Responses to Voice Pitch: The Effects of Silent Interval

1. Ronny Warrington, B.S. Au.D. Candidate Human Frequency-Following Responses to Voice Pitch: The Effects of Silent Interval

2. Introduction • Voice pitch carries important cues for speech understanding • Also carries lexical meaning for tonal languages • Frequency-following responses (FFR)

3. FFR What is an FFR? Useful tool in evaluating brain’s responses to simple and complex stimuli FFR was first described by Moushegian et al. (1973) as an objective, non-invasive method reflecting the neural phase-locking activity within the human brainstem

4. Stimulus and Parameters Silent interval Stim duration • Galbraith et al., 2000 • Galbraith et al., 2001 • Galbraith et al., 2004 • Gardi et al., 1979 • Jeng et al., 2010 • Krishnan et al., 2004 time • FFR have been recorded using

5. Issues with Silent Intervals • Recordings of FFR to voice pitch may overlap and not return to baseline when changes to the silent interval take place • Research using complex stimuli, such as phrases3 and syllables5,6, have had longer stimulus durations followed by shorter silent intervals. A B

6. Research Question and Hypothesis What is the shortest silent interval that will have no overlap in brainstem response waveforms? We hypothesize that as the silent interval decreases, FFR waveforms will increasingly overlap with adjacent waveforms as there is insufficient time for the response to return to baseline.

7. Methods Participants 12 native Mandarin Chinese speaking adults Preparation of acoustic tokens Rising /i/ tone recorded by male speaker Stimulus presentation Monaurally to right ear

8. Methods Continued Stimulus presentation cont’d 7 silent interval conditions 1 control condition (sound tube occluded) Recording parameters 3 electrodes applied to all participants (high and low forehead, right mastoid)

9. Methods Cont’d Data analysis One trial collected for each condition (8 conditions including control) -Time waveforms displayed to illustrate effects of silent intervals

10. Results • Visualization of time waveforms:

11. Statistics • RMS amplitudes for 10 ms pre-stimulus period • One way repeated measures ANOVA • No significance ( p=.079)

12. RMS Envelope • Energy of response • Transition zone (285-295 ms) • 35-45 ms silent interval

13. Hilbert Envelope • Extracted envelope from waveform • Same information as RMS envelope

14. Conclusions • Practical Significance • Transition zone: 285-295 ms • Shortest silent interval: 35-45 ms • No statistical significance • One way repeated measures ANOVA (p = 0.079)

15. References Galbraith, G.C., Bagasan, B., Sulahian, J. (2001). Brainstemfrequency-followingresponserecordedfrom one vertical and three horizontal electrodederivations. Percept Mot Skills, 92, 99-106. Galbraith, G. C., Amaya, E. M., Diaz de Rivera, J. M., et al. (2004, September). Brain stem evoked response to forward and reversed speech in humans. NeuroReport, 15(13), 2057-2060. Galbraith, G. C., Threadgill, M. R., Hemsley, J., et al. (2000). Putative measure of peripheral and brainstem frequency-following in humans. Neuroscience Letters, 292, 123-127 Gardi, J., Salamy, A., & Mendelson, T. (1979). Scalp-recorded frequency-following responses in neonates. Audiology, 18, 494-506. Jeng, F-C., Schnabel, E. A., Dickman, B. M., et al. (2010). Early maturation of frequency-following responses to voice pitch in normal hearing adults. Percept Mot Skills, 111(3), 765-784. Krishnan, A., Xu, Y., Gandour, J. T., & Cariani, P. A. (2004). Human frequency-following response: Representation of pitch contours in Chinese tones. Hearing Research, 189, 1-12. Moushegian, G., Rupert, A. L., & Stillman, R. D. (1973). Scalp-recorded early responses in man to frequencies in the speech range. Electroencephalography and Clinical Neurophysiology, 35, 665-667. Skoe, E., & Kraus, N. (2010). Auditory brain stem response to complex sounds: A tutorial. Ear &Hearing, 31, 302-324.

16. RMS Envelope