F0 Information Research Articles

Enhanced Delta Band Neural Tracking of Degraded Fundamental Frequency Speech in Noisy Environments.

Pitch variation of the fundamental frequency (F0) is critical to speech understanding, especially in noisy environments. Degrading the F0 contour reduces behaviorally measured speech intelligibility, posing greater challenges for tonal languages like Mandarin Chinese where the F0 pattern determines semantic meaning. However, neural tracking of Mandarin speech with degraded F0 information in noisy environments remains unclear. This study investigated neural envelope tracking of continuous Mandarin speech with three F0-flattening levels (original, flat-tone, and flat-all) under various SNRs (0, -9, and -12 dB). F0 contours were flattened at the word level for flat-tone and at the sentence level for flat-all Mandarin speech. Electroencephalography responses were indexed by the temporal response function in the delta (<4 Hz) and theta (4-8 Hz) frequency bands. Results show that delta-band envelope tracking is modulated by the degree of F0 flattening in a nonmonotonic manner. Notably, flat-tone Mandarin speech elicited the strongest envelope tracking compared with both original and flat-all speech, despite reduced F0 information. In contrast, the theta band, which primarily encodes speech SNR level, was not affected by F0 changes. In addition, listeners with better pitch-related music skills exhibited more efficient neural envelope speech tracking, despite being musically naive. These findings indicate that neural envelope tracking in the delta (but not theta) band is highly specific to F0 pitch variation and highlight the role of intrinsic musical skills for speech-in-noise benefits.

Mandarin-speaking Children With Cochlear Implants Face Challenges in Using F0 Expansion to Express Contrastive Focus.

Children with cochlear implants (CIs) face challenges in perceiving fundamental frequency (F0) information because CIs do not transmit F0 effectively. In Mandarin, F0 can contrast meanings at the word level, that is, via lexical tones with distinct F0 contours, and signal contrastive relations between words at the utterance-level, that is, via contrastive focus with expanded F0 range and longer duration. Mandarin-speaking children with CIs have been reported to face challenges in producing distinct F0 contours across tones, but early implantation facilitates tonal acquisition. However, it is still unclear if utterance-level prosody, such as contrastive focus, is also challenging for these children, and if early implantation also offers benefits for focus production. Therefore, this study asked how accurately children with CIs can produce contrastive focus, and if early implantation leads to more accurate focus production, with acoustic patterns approaching that of children with typical hearing (TH). Participants included 55 Mandarin-speaking children (3 to 7 years) with CIs and 55 age-matched children with TH. Children produced noun phrases with and without contrastive focus, such as RED-COLORED cat versus red-colored cat. Three adult native listeners perceptually scored the productions as correct or incorrect. The "correct" productions were then acoustically analyzed in terms of F0 range and duration. Based on the perceptual scores, children with CIs produced focus with significantly lower accuracy (38%) than their TH peers (84%). The acoustic analysis on their "correct" productions showed that children with TH used both F0 and duration to mark focus, producing focal syllables with an expanded F0 range and long duration, and postfocal syllables with a reduced F0 range and short duration. However, children with CIs differed from children with TH in that they produced focal syllables with long duration but not an expanded F0 range, although they produced postfocal syllables with a reduced F0 range and short duration like their TH peers. In addition, early implantation correlated with the percept of more accurate focus productions and better use of F0 range in focal marking. This study finds that Mandarin-speaking children with CIs are still learning to apply appropriate acoustic cues to contrastive focus. The challenge appears to lie in the use of an expanded F0 range to mark focus, probably related to the limited transmission of F0 information through the CI devices. These findings thus have implications for parents and those working with children with CIs, showing that utterance-level prosody also requires speech remediation, and underscores the critical role of identifying problems early in the acquisition of F0 functions in Mandarin, not only at the word level but also at the utterance-level.

Estimating Pitch Information From Simulated Cochlear Implant Signals With Deep Neural Networks.

Cochlear implant (CI) users, even with substantial speech comprehension, generally have poor sensitivity to pitch information (or fundamental frequency, F0). This insensitivity is often attributed to limited spectral and temporal resolution in the CI signals. However, the pitch sensitivity markedly varies among individuals, and some users exhibit fairly good sensitivity. This indicates that the CI signal contains sufficient information about F0, and users' sensitivity is predominantly limited by other physiological conditions such as neuroplasticity or neural health. We estimated the upper limit of F0 information that a CI signal can convey by decoding F0 from simulated CI signals (multi-channel pulsatile signals) with a deep neural network model (referred to as the CI model). We varied the number of electrode channels and the pulse rate, which should respectively affect spectral and temporal resolutions of stimulus representations. The F0-estimation performance generally improved with increasing number of channels and pulse rate. For the sounds presented under quiet conditions, the model performance was at best comparable to that of a control waveform model, which received raw-waveform inputs. Under conditions in which background noise was imposed, the performance of the CI model generally degraded by a greater degree than that of the waveform model. The pulse rate had a particularly large effect on predicted performance. These observations indicate that the CI signal contains some information for predicting F0, which is particularly sufficient for targets under quiet conditions. The temporal resolution (represented as pulse rate) plays a critical role in pitch representation under noisy conditions.

Vowel perception under prominence: Examining the roles of F0, duration, and distributional information.

This study investigates how prosodic prominence mediates the perception of American English vowels, testing the effects of F0 and duration. In Experiment 1, the perception of four vowel continua varying in duration and formants (high: /i-ɪ/, /u-ʊ/, non-high: /ɛ-ae/, /ʌ-ɑ/), was examined under changes in F0-based prominence. Experiment 2 tested if cue usage varies as the distributional informativity of duration as a cue to prominence is manipulated. Both experiments show that duration is a consistent vowel-intrinsic cue. F0-based prominence affected perception of vowels via compensation for peripheralization of prominent vowels in the vowel space. Longer duration and F0-based prominence further enhanced the perception of formant cues. The distributional manipulation in Experiment 2 exerted a minimal impact. Findings suggest that vowel perception is mediated by prominence in a height-dependent manner which reflects patterns in the speech production literature. Further, duration simultaneously serves as an intrinsic cue and serves a prominence-related function in enhancing perception of formant cues.

Pre-attentive fundamental frequency processing in Mandarin-speaking children with cochlear implants as revealed by the peak latency of positive mismatch response.

Fundamental frequency (F0) serves as the primary acoustic cue for Mandarin tone perception. Recent behavioral studies suggest that F0 information may be differently processed between Mandarin-speaking normal-hearing (NH) children and children with cochlear implants (CIs), which may partially explain the unsatisfactory outcome of lexical tone recognition using CIs with tonal language-oriented speech processing strategies. The aim of the current study was to provide neural evidence of F0 processing in Mandarin-speaking kindergarten-aged children with CIs compared with NH children. Positive mismatch responses (p-MMRs) to the change of the two acoustic dimensions of F0 (F0 contour and F0 level) in Mandarin-speaking kindergarten-aged children with CIs (n = 19) and their age-matched NH peers (n = 21). The two groups of children did not show any significant difference on the mean amplitude of p-MMR to either F0 contour or F0 level change. While the CI group exhibited a significantly shorter peak latency of p-MMR to F0 contour change than to F0 level change, an opposite pattern was observed in the NH group. This study revealed a higher sensitivity to F0 contour change than to F0 level change in children with CIs, which was different from that in NH children. The neural evidence of discrepant F0 processing between children with CIs and NH children in this study was consistent with the previously reported behavioral findings and may serve as a reference for the development and improvement of tonal language-oriented speech processing strategies.

Mind the subtle f0 modifications: The interaction of tone and intonation in Sinitic varieties

Sinitic varieties are well known for their complex lexical tone systems. Lesser known is that these varieties also employ intonation for multiple communicative functions, ranging from indexing a speaker’s socio-cognitive information (such as emotions and attitudes) to signaling various linguistic information (such as asking questions, marking focus, and encoding prosodic structure). This paper reviews the multiplexing of lexical tone and intonation into the same melodic f0 signal. The main empirical focus is on Standard Chinese; whenever possible, comparisons are made across Sinitic varieties (such as Shanghai Wu Chinese and Cantonese). I will show that lexical tone constrains the changes of f0 for intonation. How tone and intonation interact, however, varies across communicative contexts and language varieties, which is also reflected in how listeners utilize the f0 information to decode the melodic pitch signal during speech processing. From a cross-linguistic viewpoint, findings on intonation in Sinitic varieties suggest 1) the need for detailed acoustic and perceptual studies to understand the subtle f0 modifications for intonation in tone languages, and 2) the importance of a comparative approach to understanding the similarities and differences of intonation in tone languages.

Transfer effects of discrete tactile mapping of musical pitch on discrimination of vocoded stimuli

Many studies have found benefits of using somatosensory modality to augment sound information for individuals with hearing loss. However, few studies have explored the use of multiple regions of the body sensitive to vibrotactile stimulation to convey discrete F0 information, important for music perception. This study explored whether mapping of multiple finger patterns associated with musical notes can be learned quickly and transferred to discriminate vocoded auditory stimuli. Each of eight musical diatonic scale notes were associated with one of unique finger digits 2-5 patterns in the dominant hand, where pneumatic tactile stimulation apparatus were attached. The study consisted of a pre and post-test with a learning phase in-between. During the learning phase, normal-hearing participants had to identify common nursery song melodies presented with simultaneous auditory-tactile stimulus for about 10 min, using non-vocoded (original) audio. Pre- and post-tests examined stimulus discrimination for 4 conditions: original audio + tactile, tactile only, vocoded audio only, and vocoded audio + tactile. The audio vocoder used cochlear implant 4 channel simulation. Our results demonstrated audio-tactile learning improved participant’s performance on the vocoded audio + tactile tasks. The tactile only condition also significantly improved, indicating the rapid learning of the audio-tactile mapping and its effective transfer.

Perceptual effects of interpolated Austrian and German standard varieties

This article focuses on the perception of standard varieties produced by Austrian and German TV newscasters from the perspective of listeners from both countries, Germany and Austria. Thus, the paper's sociolinguistic scope is located in the pluricentric realm. It assesses (the perception of) standard language variation on fine phonetic levels. In addition to naturally produced stimuli (read sentences), “intermediate” samples were generated by means of a two-step interpolation procedure: First, the symbolic phone sequences were aligned with a Levenshtein-distance algorithm. Second, a phone-level Dynamic-Time-Warping (DTW) algorithm was applied to align the two utterances on a frame level, taking phoneme boundaries into account. Additionally, the spectrum and the fundamental frequency (F0) contour of the utterances was manipulated to be either interpolated or fixed to a given speaker. This procedure allowed for assessing these features’ contribution to listeners’ judgments of whether a given utterance sounds as if spoken by a speaker from (rather) Germany or (rather) Austria. Results of the judgment task showed that the interpolated samples were perceived in a continuous fashion, similarly by both groups, and with overall greater reliance on spectral than F0 information. These findings suggest that even fine phonetic differences between Standard German from Germany and Austria are recognized and evaluated by listeners from both countries. An overall bias towards perceiving all speech samples as closer to the listeners’ own national standard points to a factor of familiarity with one's own and uncertainty towards the ‘foreign’ standard. The similar degree of this bias indicates that both groups have similar levels of familiarity with their own and uncertainty about the other standard variety.

Acoustic features correlated to perceived urgency in evacuation announcements

To encourage prompt evacuation behavior during disasters, evacuation announcement systems are required to adjust the perceived urgency of announcements to the danger of a situation while maintaining voice clarity. In this study, we aimed to understand acoustic features correlated to the perceived urgency in speech when clarity is maintained. For this purpose, we used a speech synthesis tool to manipulate the key acoustic features: the time duration, F0 (instantaneous fundamental frequency), and spectrum. Specifically, we replaced these features in five real evacuation announcements that were spoken clearly by a TV announcer during an actual disaster and had different magnitudes of urgency. We found quantitatively and qualitatively that the perceived urgency was mostly influenced by the F0 of speech. Furthermore, by manipulating the F0 time average and variation, we compared the influence of the F0′s static constant feature and its dynamic fluctuation pattern on the magnitude of perceived urgency. The results indicated that both types of F0 information influenced the magnitude of perceived urgency in real Japanese speech. Our results suggest that the sense of urgency in evacuation announcements can be controlled by adjusting the F0 while maintaining voice clarity.

Parameter-Specific Morphing Reveals Contributions of Timbre to the Perception of Vocal Emotions in Cochlear Implant Users.

Objectives:Research on cochlear implants (CIs) has focused on speech comprehension, with little research on perception of vocal emotions. We compared emotion perception in CI users and normal-hearing (NH) individuals, using parameter-specific voice morphing.Design:Twenty-five CI users and 25 NH individuals (matched for age and gender) performed fearful-angry discriminations on bisyllabic pseudoword stimuli from morph continua across all acoustic parameters (Full), or across selected parameters (F0, Timbre, or Time information), with other parameters set to a noninformative intermediate level.Results:Unsurprisingly, CI users as a group showed lower performance in vocal emotion perception overall. Importantly, while NH individuals used timbre and fundamental frequency (F0) information to equivalent degrees, CI users were far more efficient in using timbre (compared to F0) information for this task. Thus, under the conditions of this task, CIs were inefficient in conveying emotion based on F0 alone. There was enormous variability between CI users, with low performers responding close to guessing level. Echoing previous research, we found that better vocal emotion perception was associated with better quality of life ratings.Conclusions:Some CI users can utilize timbre cues remarkably well when perceiving vocal emotions.

Effect of Spectral Contrast Enhancement on Speech-on-Speech Intelligibility and Voice Cue Sensitivity in Cochlear Implant Users.

Speech intelligibility in the presence of a competing talker (speech-on-speech; SoS) presents more difficulties for cochlear implant (CI) users compared with normal-hearing listeners. A recent study implied that these difficulties may be related to CI users' low sensitivity to two fundamental voice cues, namely, the fundamental frequency (F0) and the vocal tract length (VTL) of the speaker. Because of the limited spectral resolution in the implant, important spectral cues carrying F0 and VTL information are expected to be distorted. This study aims to address two questions: (1) whether spectral contrast enhancement (SCE), previously shown to enhance CI users' speech intelligibility in the presence of steady state background noise, could also improve CI users' SoS intelligibility, and (2) whether such improvements in SoS from SCE processing are due to enhancements in CI users' sensitivity to F0 and VTL differences between the competing talkers. The effect of SCE on SoS intelligibility and comprehension was measured in two separate tasks in a sample of 14 CI users with Cochlear devices. In the first task, the CI users were asked to repeat the sentence spoken by the target speaker in the presence of a single competing talker. The competing talker was the same target speaker whose F0 and VTL were parametrically manipulated to obtain the different experimental conditions. SoS intelligibility, in terms of the percentage of correctly repeated words from the target sentence, was assessed using the standard advanced combination encoder (ACE) strategy and SCE for each voice condition. In the second task, SoS comprehension accuracy and response times were measured using the same experimental setup as in the first task, but with a different corpus. In the final task, CI users' sensitivity to F0 and VTL differences were measured for the ACE and SCE strategies. The benefit in F0 and VTL discrimination from SCE processing was evaluated with respect to the improvement in SoS perception from SCE. While SCE demonstrated the potential of improving SoS intelligibility in CI users, this effect appeared to stem from SCE improving the overall signal to noise ratio in SoS rather than improving the sensitivity to the underlying F0 and VTL differences. A second key finding of this study was that, contrary to what has been observed in a previous study for childlike voice manipulations, F0 and VTL manipulations of a reference female speaker (target speaker) toward male-like voices provided a small but significant release from masking for the CI users tested. The present findings, together with those previously reported in the literature, indicate that SCE could serve as a possible background-noise-reduction strategy in commercial CI speech processors that could enhance speech intelligibility especially in the presence of background talkers that have longer VTLs compared with the target speaker.

F0-related head movement in blind versus sighted speakers.

This study investigated the relationship between head movement and fundamental frequency (F0) during speech by comparing continuous speech of congenitally blind and sighted speakers from YouTube videos. Positive correlations were found between F0 (measured in semitones) and vertical head movement for both speaker groups, with a stronger correlation for blind speakers. In addition, larger head movements and larger head movement per semitone ratios were observed for sighted speakers. These results suggest that physiological processes may account for part of the F0-related head movement and that sighted speakers use the visual modality to communicate F0 information through augmented head movement.

The Effects of Intrinsic Acoustic Cues on Categorical Perception in Children with Cochlear Implants

Many previous studies researched the influence of external cues on speech perception, yet little is known pertaining to the role of intrinsic cues in categorical perception of Mandarin vowels and tones by children with cochlear implants (CI). This study investigated the effects of intrinsic acoustic cues on categorical perception in children with CIs, compared to normal-hearing (NH) children. Categorical perception experiment paradigm was applied to evaluate their identification and discrimination abilities in perceiving /i/-/u/ with static intrinsic formants and Tone 1 (T1)-Tone 2 (T2) with dynamic intrinsic fundamental frequency (F0) contours. Results for the NH group showed that vowel continuum of /i/-/u/ was less categorically perceived than T1-T2 continuum with significantly wider boundary width and less alignment between the discrimination peak and the boundary position. However, a different categorical perception pattern was depicted for the CI group. Specifically, the CI group exhibited less categoricalness in both /i/-/u/ and T1-T2. It suggested that the effects of intrinsic acoustic cues on categorical perception was proved for the normal-hearing children, while not for the hearing-impaired children with cochlear implants. In conclusion, acoustically dynamic cues can facilitate categorical perception of speech in NH children, whereas this effect will be inhibited by difficulties in processing spectral F0 information as in the CI users.

Chinese-English Speakers' Perception of Pitch in Their Non-Tonal Language: Reinterpreting English as a Tonal-Like Language.

Changing the F0-contour of English words does not change their lexical meaning. However, it changes the meaning in tonal languages such as Mandarin. Given this important difference and knowing that words in the two languages of a bilingual lexicon interact, the question arises as to how Mandarin-English speakers process pitch in their bilingual lexicon. The few studies that addressed this question showed that Mandarin-English speakers did not perceive pitch in English words as native English speakers did. These studies, however, used English words as stimuli failing to examine nonwords and Mandarin words. Consequently, possible pre-lexical effects and L1 transfer were not ruled out. The present study fills this gap by examining pitch perception in Mandarin and English words and nonwords by Mandarin-English speakers and a group of native English controls. Results showed the tonal experience of Chinese-English speakers modulated their perception of pitch in their non-tonal language at both pre-lexical and lexical levels. In comparison to native English controls, tonal speakers were more sensitive to the acoustic salience of F0-contours in the pre-lexical processing due to top-down feedback. At the lexical level, Mandarin-English speakers organized words in their two languages according to similarity criteria based on both F0 and segmental information, whereas only the segmental information was relevant to the control group. These results in perception together with consistently reported production patterns in previous literature suggest that Mandarin-English speakers process pitch in English as if it was a one-tone language.

F0 as a secondary cue for consonant aspiration in Mandarin Chinese

Previous studies on stop production in Mandarin Chinese have reported conflicting results on consonant-induced F0 perturbation (e.g., Xu and Xu, 2003, Luo, 2018). This study investigates whether Mandarin listeners use F0 information as a cue for consonant aspiration when F0 perturbation is limited and inconsistent in production. Specifically, we examine Mandarin listeners' perception of phonological /th/-/t/ contrast, focusing on how voice onset time (VOT) and post-stop F0 influence their perceptual judgments. Mandarin listeners heard /tu/∼/thu/ syllables with the initial stop co-varying in its VOT and post-stop F0 in the four lexical tone contexts, and were asked to identify the syllable they heard. Results demonstrate Mandarin listeners relied mainly on VOT for /th/-/t/ contrast, but the effect of VOT interacted with post-stop F0 and lexical tone. F0 did not influence the perceptual judgments when VOT was unambiguous. However, when VOT was ambiguous, Mandarin listeners identified the stops with high F0 as /th/, and those with low F0 as /t/. Lexical tones mediated this effect: Tones with low pitch onset elicited more unaspirated responses than those with high pitch onset. These findings suggest that Mandarin listeners use F0 as a secondary cue for consonant aspiration, but to different extent in different lexical tones.

The influence of tone language experience and speech style on the use of intonation in language discrimination.

This work tests whether listeners' use of suprasegmental information in speech perception is modulated by language background and speech style. Native Mandarin (tone language) and Malay (non-tone language) listeners completed an AX language discrimination task with four levels of signal degradation and two speech styles. Listeners in both groups showed more benefit from pitch information in read than in spontaneous speech. Mandarin listeners showed a greater benefit than Malay listeners from the inclusion of f0 information in a segmentally degraded signal, suggesting that experience with lexical tone may extend to increased attention and/or sensitivity to phrase-level pitch contours.

Just-noticeable differences of fundamental frequency change in Mandarin-speaking children with cochlear implants

Fundamental frequency (F0) provides the primary acoustic cue for lexical tone perception in tonal languages but is poorly presented in cochlear implants (CIs). Currently, there is still a lack of understanding on the sensitivity to F0 information in CI users speaking tonal languages. In the present study, just-noticeable differences (JNDs) of F0 contour and F0 level change in Mandarin-speaking kindergarten-aged children with CIs were measured and compared with those in age-matched normal-hearing (NH) peers. Statistical analysis showed that both JND of F0 contour change (JND-C) and JND of F0 level change (JND-L) were significantly larger in CI group than in NH group. Furthermore, within-group comparison of JND-C and JND-L found that JND-C was significantly smaller than JND-L among children with CIs; however, opposite pattern was observed among children with normal hearing. The contrary sensitivity to F0 contour and F0 level change between children with CIs and children with normal hearing suggest discrepant mechanisms of F0 processing in these two groups as a result of hearing experience.Fundamental frequency (F0) provides the primary acoustic cue for lexical tone perception in tonal languages but is poorly presented in cochlear implants (CIs). Currently, there is still a lack of understanding on the sensitivity to F0 information in CI users speaking tonal languages. In the present study, just-noticeable differences (JNDs) of F0 contour and F0 level change in Mandarin-speaking kindergarten-aged children with CIs were measured and compared with those in age-matched normal-hearing (NH) peers. Statistical analysis showed that both JND of F0 contour change (JND-C) and JND of F0 level change (JND-L) were significantly larger in CI group than in NH group. Furthermore, within-group comparison of JND-C and JND-L found that JND-C was significantly smaller than JND-L among children with CIs; however, opposite pattern was observed among children with normal hearing. The contrary sensitivity to F0 contour and F0 level change between children with CIs and children with normal hearing suggest discrepan...

Factors Affecting Bimodal Benefit in Pediatric Mandarin-Speaking Chinese Cochlear Implant Users.

While fundamental frequency (F0) cues are important to both lexical tone perception and multitalker segregation, F0 cues are poorly perceived by cochlear implant (CI) users. Adding low-frequency acoustic hearing via a hearing aid in the contralateral ear may improve CI users' F0 perception. For English-speaking CI users, contralateral acoustic hearing has been shown to improve perception of target speech in noise and in competing talkers. For tonal languages such as Mandarin Chinese, F0 information is lexically meaningful. Given competing F0 information from multiple talkers and lexical tones, contralateral acoustic hearing may be especially beneficial for Mandarin-speaking CI users' perception of competing speech. Bimodal benefit (CI+hearing aid - CI-only) was evaluated in 11 pediatric Mandarin-speaking Chinese CI users. In experiment 1, speech recognition thresholds (SRTs) were adaptively measured using a modified coordinated response measure test; subjects were required to correctly identify 2 keywords from among 10 choices in each category. SRTs were measured with CI-only or bimodal listening in the presence of steady state noise (SSN) or competing speech with the same (M+M) or different voice gender (M+F). Unaided thresholds in the non-CI ear and demographic factors were compared with speech performance. In experiment 2, SRTs were adaptively measured in SSN for recognition of 5 keywords, a more difficult listening task than the 2-keyword recognition task in experiment 1. In experiment 1, SRTs were significantly lower for SSN than for competing speech in both the CI-only and bimodal listening conditions. There was no significant difference between CI-only and bimodal listening for SSN and M+F (p > 0.05); SRTs were significantly lower for CI-only than for bimodal listening for M+M (p < 0.05), suggesting bimodal interference. Subjects were able to make use of voice gender differences for bimodal listening (p < 0.05) but not for CI-only listening (p > 0.05). Unaided thresholds in the non-CI ear were positively correlated with bimodal SRTs for M+M (p < 0.006) but not for SSN or M+F. No significant correlations were observed between any demographic variables and SRTs (p > 0.05 in all cases). In experiment 2, SRTs were significantly lower with two than with five keywords (p < 0.05). A significant bimodal benefit was observed only for the 5-keyword condition (p < 0.05). With the CI alone, subjects experienced greater interference with competing speech than with SSN and were unable to use voice gender difference to segregate talkers. For the coordinated response measure task, subjects experienced no bimodal benefit and even bimodal interference when competing talkers were the same voice gender. A bimodal benefit in SSN was observed for the five-keyword condition but not for the two-keyword condition, suggesting that bimodal listening may be more beneficial as the difficulty of the listening task increased. The present data suggest that bimodal benefit may depend on the type of masker and/or the difficulty of the listening task.

The effectiveness of sound-processing strategies on tonal language cochlear implant users: A systematic review.

ImportanceContemporary cochlear implants (CIs) are well established as a technology for people with severe‐to‐profound sensorineural hearing loss, with their effectiveness having been widely reported. However, for tonal language CI recipients, speech perception remains a challenge: Conventional signal processing strategies have been demonstrated to possibly provide insufficient information to encode tonal cues, and CI recipients have exhibited considerable deficits in tone perception. Thus, some tonal language–oriented sound‐processing strategies have been introduced. The effects of available tonal language–oriented strategies on tone perception are reviewed and evaluated in this study. The results may aid in designing and improving tonal language–appropriate sound‐processing strategies for CI recipients.ObjectiveThe objective of this systematic review was to investigate the effects of tonal‐language‐oriented signal processing strategies on tone perception, music perception, word and sentence recognition.MethodsTo evaluate the effects of tonal language–oriented strategies on tone perception, we conducted a systematic review. We searched for relevant reports dated from January 1979 to July 2017 using PubMed, Cochrane Library, EBSCO, Web of Science, EMBASE, and 4 Chinese periodical databases (CBMdisc, CNKI, VIP, and Wanfang Data).ResultsAccording to our search strategy, 672 potentially eligible studies were retrieved from the databases, with 12 of these studies included in the final review after a 4‐stage selection process. The majority of sound‐processing strategies designed for tonal language were HiResolution® with Fidelity 120 (HiRes 120), fine structure processing, temporal fine structure (TFS), and C‐tone. Generally, acute or short‐term comparisons between the tonal language–oriented strategies and the conventional strategy did not reveal statistically significant differences in speech perception (or show a small improvement). However, a tendency toward improved tone perception and subjectively reported overall preferred sound quality was observed with the tonal language–oriented strategies.InterpretationConventional signal processing strategies typically provided very limited F0 information via temporal envelopes delivered to the stimulating electrodes. In contrast, tonal language–oriented coding strategies attempted to present more spectral information and TFS cues required for tone perception. Thus, a tendency of improved performance in tonal language perception in CI users was shown.

Mandarin-Speaking Children's Speech Recognition: Developmental Changes in the Influences of Semantic Context and F0 Contours.

The goal of this developmental speech perception study was to assess whether and how age group modulated the influences of high-level semantic context and low-level fundamental frequency (F0) contours on the recognition of Mandarin speech by elementary and middle-school-aged children in quiet and interference backgrounds. The results revealed different patterns for semantic and F0 information. One the one hand, age group modulated significantly the use of F0 contours, indicating that elementary school children relied more on natural F0 contours than middle school children during Mandarin speech recognition. On the other hand, there was no significant modulation effect of age group on semantic context, indicating that children of both age groups used semantic context to assist speech recognition to a similar extent. Furthermore, the significant modulation effect of age group on the interaction between F0 contours and semantic context revealed that younger children could not make better use of semantic context in recognizing speech with flat F0 contours compared with natural F0 contours, while older children could benefit from semantic context even when natural F0 contours were altered, thus confirming the important role of F0 contours in Mandarin speech recognition by elementary school children. The developmental changes in the effects of high-level semantic and low-level F0 information on speech recognition might reflect the differences in auditory and cognitive resources associated with processing of the two types of information in speech perception.