The Accompanying Effect in Responses to Auditory Perturbations: Unconscious Vocal Adjustments to Unperturbed Parameters.

PURPOSE: The present study examined whether participants respond to unperturbed parameters while experiencing specific perturbations in auditory feedback. For instance, we aim to determine if speakers adjust voice loudness when only pitch is artificially altered in auditory feedback. This phenomenon is referred to as the "accompanying effect" in the present study. METHOD: Thirty native Mandarin speakers were asked to sustain the vowel /ɛ/ for 3 s while their auditory feedback underwent single shifts in one of the three distinct ways: pitch shift (±100 cents; coded as PT), loudness shift (±6 dB; coded as LD), or first formant (F1) shift (±100 Hz; coded as FM). Participants were instructed to ignore the perturbations in their auditory feedback. Response types were categorized based on pitch, loudness, and F1 for each individual trial, such as Popp_Lopp_Fopp indicating opposing responses in all three domains. RESULTS: The accompanying effect appeared 93% of the time. Bayesian Poisson regression models indicate that opposing responses in all three domains (Popp_Lopp_Fopp) were the most prevalent response type across the conditions (PT, LD, and FM). The more frequently used response types exhibited opposing responses and significantly larger response curves than the less frequently used response types. Following responses became more prevalent only when the perturbed stimuli were perceived as voices from someone else (external references), particularly in the FM condition. In terms of isotropy, loudness and F1 tended to change in the same direction rather than loudness and pitch. CONCLUSION: The presence of the accompanying effect suggests that the motor systems responsible for regulating pitch, loudness, and formants are not entirely independent but rather interconnected to some degree.

Comparison of Involuntary and Volitional Responses to Pitch-Shifted Auditory Feedback: Evidence for Tone Speakers' Flexibility to Switch Between Opposing and Following Responses.

PURPOSE: Our audio-vocal system involves a negative feedback system that functions to correct for fundamental frequency (f 0) errors in production. Therefore, automatic and opposing responses appear when an unexpected change in voice pitch is present in auditory feedback. This study explores following responses to pitch perturbation in auditory feedback in tonal language speakers, which have been commonly overlooked or discarded by past research. We examine whether the number of response types (opposing vs. following) and their dynamic f 0 contours in tone word production vary as a function of instruction (involuntary ["to ignore"] vs. volitional ["to compensate"]). METHOD: Twenty-four native speakers of Taiwanese Southern Min (TSM) produced three disyllabic TSM words while receiving pitch perturbation through headphones. The three disyllabic words were tsau55-im55 ("out of tune"; HH), kau33-uann33 ("exchange"; MM), and pan11-an11 ("handle a case"; LL) that carry an identical high-, mid-, or low-level tone. The participants were instructed either "to ignore" or "to compensate" for the pitch shifts. RESULTS: Results from a Bayesian Poisson regression show that the number of opposing and following responses were split nearly 50-50 for the "ignore" condition and 55%-35% for the "compensate" condition. The simulation results indicate that the speakers were able to switch between the feedback and the feedforward mode during the testing. On the other hand, f 0 contour analyses using generalized additive models show that pitch-increasing responses (i.e., oppose to downshifts or follow upshifts) were significantly larger than pitch-decreasing responses (i.e., oppose to upshifts or follow downshifts) for the MM and LL words, but not for the HH word. CONCLUSIONS: Our results provide support for the view that, for tone speakers, following responses are not uncommon. The magnitudes of pitch shift response trajectories have to do with the available pitch range for moving up or down in tone word production.

The effect of stimulus timing in compensating for pitch perturbation on flat, rising, and falling contours.

The purpose of this study was to explore vocal responses to pitch perturbation on the flat, rising, and falling contour made of sequences of level tones in Taiwanese Southern Min. Twenty-two native speakers produced nine disyllabic words (flat: high-high, mid-mid, and low-low tone sequences; rising: mid-high, low-high, and low-mid tone sequences; falling: high-mid, high-low, and mid-low tone sequences). Pitch-shift stimuli (200 ms) appeared at either 100 ms (the beginning of the first syllable) or 400 ms (the beginning of the second syllable) after vocal onset. The participants were asked to ignore the pitch perturbation that appeared via auditory feedback. We found their compensation decreased when both syllables had identical level tones (i.e., the flat contour) but was particularly large when the overall contour was falling. Furthermore, pitch compensation at 100 ms was smaller than at 400 ms for the falling contour, but not for the flat and rising contours. Our results suggest that less susceptibility to pitch perturbation in the initial speech planning process is conditioned by the velocity of overall pitch contour.

Identifying distinct latent classes of pitch-shift response consistency: Evidence from manipulating the predictability of shift direction.

Auditory feedback plays an important role in regulating our vocal pitch. When pitch shifts suddenly appear in auditory feedback, the majority of the responses are opposing, correcting for the mismatch between perceived pitch and actual pitch. However, research has indicated that following responses to auditory perturbation could be common. This study attempts to explore the ways individual speakers would respond to pitch perturbation (using an opposing response or a following response) from trial to trial. Thirty-six native speakers of Mandarin produced the vowel /a/ while receiving perturbed pitch at a random time (500 ~ 700 ms) after vocal onset for a duration of 200 ms. Three blocks of 30 trials that differed in the pitch-shift stimulus direction were recorded in a randomized order: (a) the down-only condition where pitch was shifted downwards 250 cents; (b) the up-only condition where pitch was shifted upwards 250 cents; and (c) the random condition where downshifts and upshifts occurred randomly and were equally likely. The participants were instructed to ignore the pitch shifts. Results from the latent class analysis show that at the individual level across trials, 57% of participants were switchers, 28% were opposers, and 15% were followers. Our results support that speakers produce a mix of opposing and following responses when they respond to perturbed pitch. Specifically, the proportion of followers was conditional on the expectancy of pitch-shift stimulus direction: More followers were observed when the pitch-shift stimulus direction was predictable. Closer inspection of the levels of response consistency in different time phases shows that a particular mechanism (opposing or following) was initially implemented; the two mechanisms may alternate in the middle phase; and then finally, the pitch-shift response was featured as a particular mechanism near the end phase.

The effects of age and pitch level on electroglottographic measures during sustained phonation.

The aim of the present study was to use electroglottography (EGG) to explore the effects of age and pitch level on sustained vowel phonation. Thirty female individuals (10 young, 10 middle-aged, and 10 older speakers) without voice disorders or training in singing participated in this study. Eight EGG parameters were measured during sustained vowel production with a high, mid, or low pitch: fundamental frequency, contact quotient, contacting-time quotient, decontacting-time quotient, speed quotient with a midslope criterion (SQ-mid), jitter, shimmer, and the harmonics-to-noise ratio. Age was found to be a significant factor in fundamental frequency, contact quotient, contacting-time quotient, decontacting-time quotient, and SQ-mid. With increasing age, the mean fundamental frequency decreased while the contact quotient increased. The middle-aged and older speakers had more asymmetrical vocal fold vibratory patterns than the young speakers. As for pitch level, the high pitch had a significantly less decontacting-time quotient and greater SQ-mid than low and mid pitches. The lack of significant interaction between age and pitch level indicates that the effects of age and pitch level could be additive. Finally, the discriminant analyses show that contact quotient is an important factor in predicting the age of a voice.

Pitch-shift responses as an online monitoring mechanism during level tone production.

This paper investigates whether pitch-shift responses can be modulated as a function of level tone height in Taiwanese Southern Min (TSM). Twenty-six native TSM speakers were recruited and asked to produce three TSM words that differed in tone on the first syllable but had the same mid-level tone on the second syllable (hence, HM, MM, and LM). The pitch-shift stimuli appeared at 100 ms after vocalization onset and lasted for 200 ms. The magnitudes of the pitch-shift stimuli were ±250 cents for HM, +250/-150 cents for MM, and ±150 cents for LM, in order to overlap the shifted pitch with another lexical tone. The results show that larger pitch-shift peak amplitudes were elicited when the H level tone of the HM word was downshifted 250 cents to the M level and when the L level tone of the LM word was upshifted 150 cents to the M level tone. However, no significant direction effect was found for the MM word. The M level tone might be perceived non-categorically by native TSM speakers. Overall, the findings suggest that the magnitudes of pitch-shift responses may have to do with the degree of categorical perception.

Suppression of vocal responses to auditory perturbation with real-time visual feedback.

Speakers can adjust pitch using auditory feedback through a short-latency corrective response known as the pitch-shift response (PSR). Suppression of the PSR denotes on-line stabilization of pitch. In this paper, the hypothesis that pitch-shift responses can be suppressed with real-time visual feedback of vocal F0 is investigated. Mandarin speakers and naive speakers without tonal language experience were instructed to produce the sustained vowel /a/ and Mandarin tone /ma1/ in an audio-only condition and a separate audio-visual condition. Both Mandarin speakers and naive speakers suppressed pitch-shift responses in the audio-visual condition, regardless of task (/a/ or /ma1/) and stimulus magnitude (25 cents or 200 cents). These findings suggest that multisensory feedback (audio-visual) can improve the stability of voice F0. The benefit of audio-visual integration is independent of language experience.