Frequency-Following Responses to Voice Pitch in Chinese Neonates and Adults

1. Frequency-Following Responses to Voice Pitch in Chinese Neonates and Adults Jiong Hu, Fuh-Cherng Jeng School of Hearing, Speech and Language Sciences, Ohio University, Athens, Ohio, USA RESULTS • INTRODUCTION • A person’s ability to perceive the spectral and temporal contents of sounds is important because it reflects the brain’s ability to perceive differences in the pitch of the voice. This ability is critical for listeners to differentiate pitch changes among speech sounds. Recent studies have shown the feasibility of recording a frequency-following response (FFR) using speech sounds in adults (Aiken & Picton, 2006; Dajani, Purcell, Wong, Kunov, & Picton, 2005; Krishnan, 2002; Krishnan & Xu, 2004; Krishnan, Xu, Gandour, & Cariani, 2005). Little has been reported about the characteristics of the speech-elicited FFR in neonates. Recording and characterizing the FFR to voice pitch in neonates and comparing to those obtained in adults will help determine whether the “innate” prelinguistic capacity model or the post-natal “linguistic experience” model dominates the signal processing of voice pitch during the early stages of life. The purpose of this study was to evaluate the characteristics of the FFR to voice pitch in neonates during their immediate post-natal period. • METHOD • PARTICIPANTS • - 12 normal-hearing Chinese neonates (age 1-3 days) • - 12 normal-hearing adults speakers of native Chinese • STIMULUS • - Monosyllabic Mandarin Chinese lexical tone with a rising F0 contour • PROCEDURE • - Electrodes placed on Fpz and on each mastoid • - State of restfulness was achieved • - Stimuli: - 2 trials of 1200 repetitions • - neonates: 65 dB SPL, adults 70 dB SPL • DATA ANALYSIS • - 1200 epochs for each session, bandpass filtered • (100-1500 Hz, 6 dB/oct) • - Cross correlation of the stimulus and recorded • waveforms were performed to identify the location • that contains the maximum cross-correlation value • between 2-10 ms response window • - To visualize the FFR in a spectrogram, a periodicity • detection short-term autocorrelation algorithm (Boersma, 1993) were carried out on each trial. • F0 CONTOUR EXTRACTING AUGORITHMS • - Spectral-density-maxima: • * The f0 contour was estimated based on the maximal value of spectral density in a pre-defined rectangular range (90-180 Hz). • * For each time point, the frequency that corresponded to the maximal spectral density was used to represent the instantaneous f0 value at that time point. • - Short-term autocorrelation (Boersma,1993) DISCUSSION This study demonstrated: (1) Neonates demonstrated the ability to follow the fundamental frequency contours of the stimulus at their immediate post-natal period (Figure 1). (2) Neonates showed comparable pitch-tracking ability to adults (Figure 3). This result may be in support of the “innate” or “biological” pre-linguistic capacity model. (3) The smaller head sizes of neonates may have affected the pitch strength of the recorded neonatal FFR. (4) Higher harmonic information of the stimulus was not reflected in the recorded neonatal FFR. This finding may suggest that such an ability to process higher harmonics may be dependent on linguistic experience developed later in life. ● Neonate FFR to voice pitch ● F0 contours extracted using two methods A Stimulus Fig. 1 (left) Spectrogram s of (A) stimulus (B) grand averaged FFR recording of neonates ,and (C) grand averaged FFR recording from adults. Fig. 2 (right)For both participants groups, fundamental frequency contours were extracted using two methods: Upper: Short-term Autocorrelation Lower: Narrow-band Spectral-density-maxima B C ACKNOWLEDGMENTS This study is supported in part by Advancing Academic-Research Career (AARC) Award American Speech-Language-Hearing Association Part of the data collection was completed at Nanjing Marternity and Child Health Care Hospital in Nanjing, China. Adult Neonate • REFERENCES • Aiken, S.J., Picton, T.W. (2006). Envelope following responses to natural vowels. Audiology & Neuro-Otology, 11(4), 213-232. • Boersma P: Accurate short-term analysis of the fundamental frequency and the harmonics-to-noise ratio of a sampled sound. Proc Inst Phon Sci 1993;17:97-110. • Dajani, H.R., Purcell, D., Wong, W., Kunov, H., Picton, T.W. (2005). Recording human evoked potentials that follow the pitch contour of a natural vowel. IEEE Transactions on Biomedical Engineering, 52(9), 1614-1618. • Gardi, J., Salamy, A., Mendelson, T. (1979). Scalp-recorded frequency-following responses in neonates. Audiology: Journal of Auditory Communication, 18(6), 494-506 • Krishnan, A., Xu, Y., Gandour, J., Cariani, P. (2004). Human frequency-following response: Representation of pitch contours in Chinese tones. Hearing Research,189,1-12. • Krishnan, A., Xu, Y., Gandour, J., Cariani, P. (2005). Encoding of pitch in the human brainstem is sensitive to language experience. Cognitive Brain Research, 25(1), 161-168. • Russo, N.M. et al. (2008). Deficit brainstem encoding of pitch in children with Autism Spectrum Disorders. Clinical Neurophysiology, 119, 1720-1731. ● No significant difference in pitch tracking ability between neonates and adults Fig. 3 Group comparison of the pitch tracking ability between neonatal FFR and adult FFR. Four indices were used : Pitch-tracking Accuracy , Intercept Error , Slope Error, Frequency Error, and Pitch Strength. • CONTACT INFORMATION • Jiong Hu • School of Hearing, Speech and Language Sciences • Ohio University • Athens, OH 45701 • E-mail: jh139306@ohio.edu