An automated procedure for detecting human frequency-following responses to voice pitch

The frequency-following response (FFR) to voice pitch has been widely examined in research laboratories and has demonstrated its potential to be transformed into a useful tool for patients with hearing, speech, and language disorders in the clinic. During the past decade, many aspects of the FFR have been reported. The presence of such a response, however, still relies on subjective interpretation of the observer. Aside from a recent study reporting two algorithms for detecting such a response, there has been limited number of studies reporting the development of an automated procedure for FFR. The purpose of this study is (1) to develop an automated procedure that utilizes the statistical properties of the temporal and spectral energy distributions in the recorded waveforms and (2) to examine the sensitivity and specificity of the automated procedure. © 2013 Acoustical Society of America

Exponential modeling of human frequency-following responses to voice pitch

Objective: Recent studies have shown that the frequency-following response (FFR) to voice pitch can be a useful method to evaluate the signal-processing mechanisms and neural plasticity in the human brainstem. The purpose of this study was to examine the quantitative properties of the FFR trends with an exponential curve-fitting model. Design: FFR trends obtained with increasing number of sweeps (up to 8000 sweeps) at three stimulus intensities (30, 45, and 60 dB nHL) were fit to an exponential model that consisted of estimates of background noise amplitude, asymptotic response amplitude, and a time constant. Five objective indices (Frequency Error, Slope Error, Tracking Accuracy, Pitch Strength and RMS Ratio) were used to represent different perspectives of pitch processing in the human brainstem. Study Sample: Twenty-three native speakers (16 males; age = 24.7 ± 2.1 years) of Mandarin Chinese were recruited. Results: The results demonstrated that the exponential model provided a good fit (r = 0.89 ± 0.10) to the FFR trends with increasing number of sweeps for the five objective indices. Conclusions: The exponential model, combined with the five objective indices, can be used for difficult-to-test patients and may prove to be useful as an assessment and diagnostic method in both clinical and basic research efforts. © 2011 British Society of Audiology, International Society of Audiology, and Nordic Audiological Society.

Cross-linguistic comparison of frequency-following responses to voice pitch in american and chinese neonates and adults

OBJECTIVES: Cross-language studies, as reflected by the scalp-recorded frequency-following response (FFR) to voice pitch, have shown the influence of dominant linguistic environments on the encoding of voice pitch at the brainstem level in normal-hearing adults. Research questions that remained unanswered included the characteristics of the FFR to voice pitch in neonates during their immediate postnatal period and the relative contributions of the biological capacities present at birth versus the influence of the listener\u27s postnatal linguistic experience. The purpose of this study was to investigate the characteristics of FFR to voice pitch in neonates during their first few days of life and to examine the relative contributions of the biological capacity versus linguistic experience influences on pitch processing in the human brainstem. DESIGN: Twelve American neonates (five males, 1-3 days old) and 12 Chinese neonates (seven males, 1-3 days old) were recruited to examine the characteristics of the FFRs during their immediate postnatal days of life. Twelve American adults (three males; age: mean ± SD = 24.6 ± 3.0 yr) and 12 Chinese adults (six males; age: mean ± SD = 25.3 ± 2.6 yr) were also recruited to determine the relative contributions of biological and linguistic influences. A Chinese monosyllable that mimics the English vowel /i/ with a rising pitch (117-166 Hz) was used to elicit the FFR to voice pitch in all participants. RESULTS: Two-way analysis of variance (i.e., the language [English versus Chinese] and age [neonate versus adult] factors) showed a significant difference in Pitch Strength for language (p = 0.035, F = 4.716). A post hoc Tukey-Kramer analysis further demonstrated that Chinese adults had significantly larger Pitch Strength values than Chinese neonates (p = 0.024). This finding, coupled with the fact that American neonates and American adults had comparable Pitch Strength values, supported the linguistic experience model. On the other hand, Pitch Strength obtained from the American neonates, American adults, and Chinese neonates were not significantly different from each other, supporting the biological capacity model. CONCLUSIONS: This study demonstrated an early maturation of voice-pitch processing in neonates starting from 1 to 3 days after birth and a significant effect of linguistic experience on the neural processing of voice pitch at the brainstem level. These findings provide a significant conceptual advancement and a basis for further examination of developmental maturation of subcortical representation of speech features, such as pitch, timing, and harmonics. These findings can also be used to help identify neonates at risk for delays in voice-pitch perception and provide new directions for preventive and therapeutic interventions for patients with central auditory processing deficits, hearing loss, and other types of communication disorders. Copyright © 2011 by Lippincott Williams & Wilkins

Early maturation of frequency-following responses to voice pitch in infants with normal hearing

Neural plasticity of pitch processing mechanisms at the human brainstem, as reflected by the scalp-recorded frequency-following response (FFR) to voice pitch, has been reported for normal-hearing adults. Characteristics and maturation of such a response during the first year of life have remained unclear. The purpose of this study was to examine the characteristics of FFR to voice pitch in normal-hearing infants and to make a direct comparison with adults using the same stimulus and recording parameters. 9 infants and 9 adults were recruited. A Chinese monosyllable that mimics the English vowel /i/ with a rising pitch was used to elicit the FFR to voice pitch. The results demonstrated that infant FFRs showed slightly larger Pitch Strength but comparable Frequency Error, Slope Error, and Tracking Accuracy to those obtained from adults. Early maturation of FFRs was also observed in the infants starting from 1 to 3 mo. of age. © Perceptual and Motor Skills 2010

Evaluation of two algorithms for detecting human frequency-following responses to voice pitch

Objective. Voice pitch carries important cues for speech perception in humans. Recent studies have shown the feasibility of recording the frequency-following response (FFR) to voice pitch in normal-hearing listeners. The presence of such a response, however, has been dependent on subjective interpretation of experimenters. The purpose of this study was to develop and test an automated procedure including a control-experimental protocol and response-threshold criteria suitable for extracting FFRs to voice pitch, and compare the results to human judgments. Design. A set of four Mandarin tones (Tone 1 flat; Tone 2 rising; Tone 3 dipping; and Tone 4 falling) were prepared to reflect the four contrastive pitch contours. Two distinctive algorithms, short-term autocorrelation in the time domain and narrow-band spectrogram in the frequency domain, were used to estimate the Frequency Error, Slope Error, Tracking Accuracy, Pitch Strength and Pitch-Noise Ratio of the recordings from individual listeners as well as the power and false-positive rates of each algorithm. Study Sample. Eleven native speakers (five males; age: mean ± SD 31.4 ± 4.7 years) of Mandarin Chinese were recruited. Results. The results demonstrated that both algorithms were suitable for extracting FFRs and the objective measures showed comparable results to human judgments. Conclusions. The automated procedure used in this study, including the use of the control-experimental protocol and response thresholds used for each of the five objective indices, can be used for difficult-to-test patients and may prove to be useful as an assessment and diagnostic method in both clinical and basic research efforts. © 2011 British Society of Audiology, International Society of Audiology, and Nordic Audiological Society