Voice Pitch Elicited Frequency Following Response in Chinese Elderlies

Abstract

Background: Perceptual and electrophysiological studies have found reduced speech discrimination in quiet and noisy environment, delayed neural timing, decreased neural synchrony, and decreased temporal processing ability in elderlies, even those with normal hearing. However, recent studies have also demonstrated that language experience and auditory training enhance the temporal dynamics of sound encoding in the auditory brainstem response (ABR). The purpose of this study was to explore the pitch processing ability at the brainstem level in an aging population that has a tonal language background.Method: Mandarin speaking younger (n = 12) and older (n = 12) adults were recruited for this study. All participants had normal audiometric test results and normal suprathreshold click-evoked ABR. To record frequency following responses (FFRs) elicited by Mandarin lexical tones, two Mandarin Chinese syllables with different fundamental frequency pitch contours (Flat Tone and Falling Tone) were presented at 70 dB SPL. Fundamental frequencies (f0) of both the stimulus and the responses were extracted and compared to individual brainstem responses. Two indices were used to examine different aspects of pitch processing ability at the brainstem level: Pitch Strength and Pitch Correlation.Results: Lexical tone elicited FFR were overall weaker in the older adult group compared to their younger adult counterpart. Measured by Pitch Strength and Pitch Correlation, statistically significant group differences were only found when the tone with a falling f0 (Falling Tone) were used as the stimulus.Conclusion: Results of this study demonstrated that in a tonal language speaking population, pitch processing ability at the brainstem level of older adults are not as strong and robust as their younger counterparts. Findings of this study are consistent with previous reports on brainstem responses of older adults whose native language is English. On the other hand, lexical tone elicited FFRs have been shown to correlate with the length of language exposure. Older adults’ degraded responses in our study may also be due to that, the Mandarin speaking older adults’ long term exposure somewhat counteracted the negative impact on aging and helped maintain, or at least reduced, the degradation rate in their temporal processing capacity at the brainstem level.

Effects of Inter-Stimulus Interval on Speech-Evoked Frequency-Following Response in Elderly Adults

“…Our data revealed that although the responses were weaker than the younger adults, older adults’ FFR did not appear to be more susceptible to differing ISI lengths, some as short as 40 ms. The 40 ms ISI has been widely used in the FFR literature for Mandarin Chinese speech stimuli in younger adults (Krishnan et al, 2004 , 2005 ; Jeng et al, 2011 ; Wang et al, 2016 ). In the current study, it did not seem to be too short for the older adults’ FFR, reflected by the two indices, stimulus-to-response correlation coefficient and the pitch strength.…”

“…Pitch strength is defined as the distance between of the maximum of and the minimum of the autocorrelation function. For detailed discussion on these two indices, please refer to our previous work in Jeng and Warrington ( 2011 ) and Wang et al ( 2016 ).…”

“…For example, Clinard et al ( 2010 ) demonstrated that older adults, even with normal hearing sensitivity, have auditory perceptual deficits relative to their young counterparts. Similarly, Wang et al ( 2016 ) demonstrated that pitch processing ability at the brainstem level of the elderly were not as strong as younger adults in tonal language speakers.…”

Brainstem Encoding of Speech and Music Sounds in Humans

“…Another form of auditory expertise-musicianship-also produces stronger pitch-tracking responses (Wong et al, 2007). On the other hand, even within tone-language speakers, a decline in FFR pitch tracking is seen in older adults (Wang et al, 2016). Russo et al (Russo et al, 2008) noted weaker pitch tracking in school-age children on the autism spectrum compared to typically developing peers, evocative of the characteristic flat affect in the speech of some autistic individuals and the diminished ability to perceive emotional valence (Matsumoto et al, 2016).…”

Decoding Speech and Music Stimuli from the Frequency Following Response

“…For example, the FFR is thought to be related to auditory experience, such that stronger FFRs are observed with greater degrees of musical skill (Musacchia et al, 2007; N. Kraus & Strait, 2015; Parbery-Clark et al, 2012; Wong et al, 2007) or language experience (Krishnan et al, 2005; S Wang et al, 2016Song et al, 2008).…”