Target F0 Research Articles

Effect of relative timing of target and background words on speech understanding using the coordinate response measure paradigm

Recognition of target keywords in CRM sentences in the presence of competing CRM sentences has been shown to depend upon both the rhythmic context of target and background speech and F0 differences between target and background speakers. The present study investigated the role of the relative timing of target and background keywords for background keywords that were presented either in isolation (Experiment 1) or embedded within their associated background context (Experiment 2) for target and background material that was spoken by the same male talker. In Experiment 1, onset asynchrony of target and background keywords varied between –200 ms and 200 ms. Results showed an asymmetric U-shaped performance curve where (1) target recognition improved with increasing deviation of background keywords from the expected onset timing of target keywords and (2) target words were better recognized when they began before background keywords compared to when they began after. In Experiment 2, where background keywords were embedded within their original CRM context, performance was reduced to chance for both an intact background rhythm condition and a range of altered background rhythm conditions. Results will be discussed in terms of a selective entrainment hypothesis and the role of F0 differences in speech segregation.

The effect of target/masker fundamental frequency contour similarity on masked-speech recognition.

Greater informational masking is observed when the target and masker speech are more perceptually similar. Fundamental frequency (f0) contour, or the dynamic movement of f0, is thought to provide cues for segregating target speech presented in a speech masker. Most of the data demonstrating this effect have been collected using digitally modified stimuli. Less work has been done exploring the role of f0 contour for speech-in-speech recognition when all of the stimuli have been produced naturally. The goal of this project was to explore the importance of target and masker f0 contour similarity by manipulating the speaking style of talkers producing the target and masker speech streams. Sentence recognition thresholds were evaluated for target and masker speech that was produced with either flat, normal, or exaggerated speaking styles; performance was also measured in speech spectrum shaped noise and for conditions in which the stimuli were processed through an ideal-binary mask. Results confirmed that similarities in f0 contour depth elevated speech-in-speech recognition thresholds; however, when the target and masker had similar contour depths, targets with normal f0 contours were more resistant to masking than targets with flat or exaggerated contours. Differences in energetic masking across stimuli cannot account for these results.

Effects of residual masker, spectral resolution, and low frequency cues on the perception of ideal binary-masked speech

This study investigated the intelligibility of ideal binary-masked (IdBM) stimuli under conditions with limited spectral resolution. In experiment 1, we used different IdBM local thresholds, which retain different amounts of residual masker and target information in the IdBM-stimuli. The stimuli were presented to 30 normal hearing listeners. The results indicated that, with a 6- or 12-channel tone-vocoder, the presence of residual masker in the IdBM-stimuli limits the intelligibility scores, thus preventing IdBM processing from achieving an ideal segregation of target from masker. In experiment 2, we investigated whether introduction of low frequency target information to the tone-vocoded IdBM-stimuli improves the intelligibility scores. Twenty normal hearing listeners participated in this experiment. The results indicated that in contrast to target F0 cues, inclusion of low-pass filtered target information (cutoff = 300 Hz) helped listeners segregate the target from the masker, thus improving the intelligibility of the IdBM-stimuli. These results argue against F0 as a segregation cue in electroacoustic conditions and suggest that target F0 cues do not provide benefits beyond those provided by IdBM.

Robustness against distortion of fundamental frequency cues in simulated electro-acoustic hearing.

Speech recognition by cochlear implant users can be improved by adding an audible low frequency acoustic signal to electrical hearing; the resulting improvement is deemed "electro-acoustic stimulation (EAS) benefit." However, a crucial low frequency cue, fundamental frequency (F0), can be distorted via the impaired auditory system. In order to understand how F0 distortions may affect EAS benefit, normal-hearing listeners were presented monaurally with vocoded speech (frequencies >250 Hz) and an acoustical signal (frequencies <250 Hz) with differing manipulations of the F0 signal, specifically: a pure tone with the correct mean F0 but with smaller variations around this mean, or a narrowband of white noise centered around F0, at varying bandwidths; a pure tone down-shifted in frequency by 50 Hz but keeping overall frequency modulations. Speech-recognition thresholds improved when tones with reduced frequency modulation were presented, and improved significantly for noise bands maintaining F0 information. A down-shifted tone, or only a tone to indicate voicing, showed no EAS benefit. These results confirm that the presence of the target's F0 is beneficial for EAS hearing in a noisy environment, and they indicate that the benefit is robust to F0 distortion, as long as the mean F0 and frequency modulations of F0 are preserved.

Internal and contextual cues to tone perception in Medʉmba.

This study presents results of an identification experiment with speakers of Medʉmba, a Grassfields Bantu language, aimed at evaluating the relative effects of f0 and duration in cuing tonal contrasts, as well as the role of lexical vs non-speech pitch contexts in biasing tone perception. Results show that duration is a cue for tone perception, with the influence of duration strongest where target f0 values were lower. Lexical tone perception is also sensitive to the identity of a preceding lexical tone, but not to the presence of a preceding non-speech pure tone.

Interactions of subglottal pressure and neuromuscular activation on fundamental frequency and intensity.

Fundamental frequency (F0) and intensity sound pressure level (SPL) of voice are controlled by intrinsic laryngeal muscle (ILM) activation and subglottal pressure (Psub). Their interactions were investigated. In an in vivo canine model, the thyroarytenoid (TA), lateral cricoarytenoid/interarytenoid (LCA/IA), and cricothyroid (CT) muscles were independently activated from threshold to maximal contraction by neuromuscular stimulation in various combinations, whereas airflow was increased to phonation onset pressure and beyond. The resultant acoustic output was analyzed for effects of Psub on vibratory stability, F0, and SPL. Muscle activation plots and vocal range profiles by individual ILM activation states were analyzed. Cricothyroid activation increased phonation onset F0, but vibration was less stable in high CT conditions and displayed vibratory mode change. In addition, a decrease in F0 with increased Psub was observed in high CT conditions. Intensity increased with Psub in all conditions, but the slope was greater at high CT, low TA/LCA/IA activations. Lateral cricoarytenoid/interarytenoid activation improved vocal efficiency. To maintain same F0 with increasing SPL (messa di voce), TA activation was decreased and LCA/IA activation was increased. The same F0 and SPL could be achieved with a variety of ILM activation combinations. Cricothyroid is primarily required for increasing F0, whereas TA can increase or decrease F0 and SPL. Lateral cricoarytenoid/interarytenoid activation likely maintains vocal fold adduction during increased Psub and improves vocal efficiency. This study also demonstrates laryngeal motor equivalence, the ability of the larynx to achieve the same target F0 and SPL with multiple combinations of ILM activation. N/A. Laryngoscope, 126:1123-1130, 2016.

Shifting Fundamental Frequency in Simulated Electric-Acoustic Listening

Shifting the mean fundamental frequency (F0) of target speech down in frequency may be a way to provide the benefits of electric-acoustic stimulation (EAS) to cochlear implant (CI) users whose limited residual hearing precludes a benefit typically, even with amplification. However, previous study showed a decline in the amount of benefit at the greatest downward frequency shifts, and the authors hypothesized that this might be related to F0 variation. Thus, in the present study, the authors sought to determine the relationship between mean F0, F0 variation, and the benefits of combining electric stimulation from a CI with low-frequency residual acoustic hearing. The authors measured speech intelligibility in normal-hearing listeners using an EAS simulation consisting of a sine vocoder combined either with speech low-pass filtered at 500 Hz, or with a pure tone representing target F0. The authors used extracted target voice pitch information to modulate the tone, and manipulated both the frequency of the carrier (mean F0), as well as the standard deviation of the voice pitch information (F0 variation). A decline in EAS benefit was observed at the lowest mean F0 tested, but this decline disappeared when F0 variation was reduced to be proportional to the amount of the shift in frequency (i.e., when F0 was shifted logarithmically instead of linearly). Lowering mean F0 by shifting the frequency of a pure tone carrying target voice pitch information can provide as much EAS benefit as an unshifted tone, at least in the current simulation of EAS. These results may have implications for CI users with extremely limited residual acoustic hearing.

Direct and Octave-Shifted Pitch Matching During Nonword Imitations in Men, Women, and Children

To evaluate whether children, women, and men match the speaker's fundamental frequency (F0) during nonword imitation directly when the target F0 is within the responders' vocal ranges and at octave-shifted levels when the target is outside their vocal ranges, and to evaluate the role of a history of speech sound disorder (SSD) in the adult participants. Observational. Nonword sets spoken by a man and a woman were imitated by 14 men, 21 women, and 19 children. Approximately half of the adults and two-thirds of the children had a history of SSD. F0 in the imitations was compared with that in the targets and in the participants' nonimitated control word productions. When the target F0 was within the responders' vocal ranges, the imitations approximated the target F0. Men imitating a woman's voice approximated F0 levels one octave below the target F0. Children imitating a man's voice approximated F0 levels one octave above the target F0. Women imitating a man's voice approximated the target F0 at a ratio of 1.5 known as the perfect fifth in music. A history of SSD did not influence the results. This study replicates previous findings showing that target F0 was a salient aspect of the stimuli that was imitated along with the targets' segmental and prosodic components without explicit prompting. It is the first to show F0 convergence not only directly but also at relevant target/imitation intervals including the octave interval.

Roles of the target and masker fundamental frequencies in voice segregation.

Intelligibility of a target voice improves when its fundamental frequency (F0) differs from that of a masking voice, but it remains unclear how this masking release (MR) depends on the two relative F0s. Three experiments measured speech reception thresholds (SRTs) for a target voice against different maskers. Experiment 1 evaluated the influence of target F0 itself. SRTs against white noise were elevated by at least 2 dB for a monotonized target voice compared with the unprocessed voice, but SRTs differed little for F0s between 50 and 150 Hz. In experiments 2 and 3, a MR occurred when there was a steady difference in F0 between the target voice and a stationary speech-shaped harmonic complex or a babble. However, this MR was considerably larger when the F0 of the masker was 11 semitones above the target F0 than when it was 11 semitones below. In contrast, for a fixed masker F0, the MR was similar whether the target F0 was above or below. The dependency of these MRs on the masker F0 suggests that a spectral mechanism such as glimpsing in between resolved masker partials may account for an important part of this phenomenon.

Auditory Cortex Represents Both Pitch Judgments and the Corresponding Acoustic Cues

SummaryThe neural processing of sensory stimuli involves a transformation of physical stimulus parameters into perceptual features, and elucidating where and how this transformation occurs is one of the ultimate aims of sensory neurophysiology. Recent studies have shown that the firing of neurons in early sensory cortex can be modulated by multisensory interactions [1–5], motor behavior [1, 3, 6, 7], and reward feedback [1, 8, 9], but it remains unclear whether neural activity is more closely tied to perception, as indicated by behavioral choice, or to the physical properties of the stimulus. We investigated which of these properties are predominantly represented in auditory cortex by recording local field potentials (LFPs) and multiunit spiking activity in ferrets while they discriminated the pitch of artificial vowels. We found that auditory cortical activity is informative both about the fundamental frequency (F0) of a target sound and also about the pitch that the animals appear to perceive given their behavioral responses. Surprisingly, although the stimulus F0 was well represented at the onset of the target sound, neural activity throughout auditory cortex frequently predicted the reported pitch better than the target F0.

Quality Comparison of Continuous Steam Sterilization Segmented‐Flow Aseptic Processing versus Conventional Canning of Whole and Sliced Mushrooms

This study was carried out to investigate segmented-flow aseptic processing of particle foods. A pilot-scale continuous steam sterilization unit capable of producing shelf stable aseptically processed whole and sliced mushrooms was developed. The system utilized pressurized steam as the heating medium to achieve high temperature-short time processing conditions with high and uniform heat transfer that will enable static temperature penetration studies for process development. Segmented-flow technology produced a narrower residence time distribution than pipe-flow aseptic processing; thus, whole and sliced mushrooms were processed only as long as needed to achieve the target F₀ = 7.0 min and were not overcooked. Continuous steam sterilization segmented-flow aseptic processing produced shelf stable aseptically processed mushrooms of superior quality to conventionally canned mushrooms. When compared to conventionally canned mushrooms, aseptically processed yield (weight basis) increased 6.1% (SD = 2.9%) and 6.6% (SD = 2.2%), whiteness (L) improved 3.1% (SD = 1.9%) and 4.7% (SD = 0.7%), color difference (ΔE) improved 6.0% (SD = 1.3%) and 8.5% (SD = 1.5%), and texture improved 3.9% (SD = 1.7%) and 4.6% (SD = 4.2%), for whole and sliced mushrooms, respectively. Segmented-flow aseptic processing eliminated a separate blanching step, eliminated the unnecessary packaging of water and promoted the use of bag-in-box and other versatile aseptic packaging methods. Segmented-flow aseptic processing is capable of producing shelf stable aseptically processed particle foods of superior quality to a conventionally canned product. This unique continuous steam sterilization process eliminates the need for a separate blanching step, reduces or eliminates the need for a liquid carrier, and promotes the use of bag-in-box and other versatile aseptic packaging methods.

Pitch discrimination interference: The role of ear of entry and of octave similarity

Gockel et al. [(2004). J. Acoust. Soc. Am. 116, 1092-1104] reported that discrimination of the fundamental frequency (F0) of two sequentially presented complex tones (the target) was impaired when an additional complex tone (the interferer) was presented simultaneously with and to the same ear as the target, even though the target and interferer were filtered into separate frequency regions. This pitch discrimination interference (PDI) was greatest when the target and interferer had similar F0s. The current study examined the role of relative ear of entry of the target and interferer and whether the dependence of the PDI effect on the relative F0 of target and interferer is based on pitch height (F0 as such) or pitch chroma (the musical note). Sensitivity (d(')) was measured for discrimination of the F0 of a target with a nominal F0 of 88 Hz, bandpass filtered from 1375 to 1875 Hz. The interferer was bandpass filtered from 125 to 625 Hz. The contralateral interferer produced marked PDI, but smaller than for ipsilateral presentation. PDI was not larger when the interferer's F0 was twice the nominal target F0 than when it was a factor of 1.9 or 2.1 higher.

Impact of Muscle Tension Dysphonia on Tonal Pitch Target Implementation in Vietnamese Female Teachers

Muscle tension dysphonia (MTD) is a voice disorder with deteriorated vocal quality, particularly pitch problems. Because pitch is mainly controlled by the laryngeal muscles, and because MTD is characterized by increased laryngeal muscle tension, we hypothesized that it may result in problems in pitch target implementation in tonal languages. We examined tonal samples of 42 Vietnamese female primary school teachers diagnosed with MTD and compared them with 30 vocally healthy female teachers who spoke the same dialect. Tonal data were analyzed using Computerized Speech Lab (CSL-4300B) for Windows. From tonal sampling bases, fundamental frequency (F0) was measured at target points specified by contour examination. Parameters representing pitch movement including time, size, and speed of movement were measured for the falling tone and rising tone. We found that F0 at target points in MTD group was lowered in most tones, especially tones with extensive F0 variation. In MTD group, target F0 of the broken tone in isolation was 37.5 Hz lower (P<0.01) and target F0 of rising tone in isolation was 46 Hz lower (P<0.01) than in control group. In MTD group, speed of pitch fall of the falling tone in isolation was faster than control group by 2.2 semitones/second (st/s) (P<0.05) and speed of pitch rise in the rising tone in isolation was slower than control group by 7.2 st/s (P<0.01). These results demonstrate that MTD is associated with problems in tonal pitch variation.

Effects of reverberation on perceptual segregation of competing voices by difference in fundamental frequency

Three experiments investigated the effect of reverberation on listeners' ability to use the difference in fundamental frequency (F0) between a target and an interfering voice to perceptually separate them. Speech reception thresholds (SRTs) were measured for a monotonized or frequency-modulated male voice against one or two other monotonized or frequency-modulated male voices or against a speech-shaped, pulse train within a virtual room with controlled reverberation. The sources of targets and interferers were always co-located both straight ahead of the listener. In the two first experiments, the beneficial effect of a F0 difference was reduced in reverberation when the target and interferer's F0 were frequency-modulated at 5 Hz. Experiment 3 investigated this interaction between reverberation, a F0 difference and the target and/or interferer F0's modulation: the results highlighted the relevance of the interferer F0's modulation alone in the presence of reverberation. This finding is consistent with the idea that the effect of F0 difference is mediated by a harmonic-cancellation process. The cancellation of the interferer is disrupted by the reverberation only when the interferer's F0 is frequency-modulated, irrespective of the modulation of the target's F0. A frequency-overlap between the F0 of the target and the maskers does not seem a cause of worse impairment in intelligibility.

Across-frequency interference effects in fundamental frequency discrimination: questioning evidence for two pitch mechanisms.

Carlyon and Shackleton [J. Acoust. Soc. Am. 95, 3541-3554 (1994)] presented an influential study supporting the existence of two pitch mechanisms, one for complex tones containing resolved and one for complex tones containing only unresolved components. The current experiments provide an alternative explanation for their finding, namely the existence of across-frequency interference in fundamental frequency (F0) discrimination. Sensitivity (d') was measured for F0 discrimination between two sequentially presented 400 ms complex (target) tones containing only unresolved components. In experiment 1, the target was filtered between 1375 and 15,000 Hz, had a nominal F0 of 88 Hz, and was presented either alone or with an additional complex tone ("interferer"). The interferer was filtered between 125-625 Hz, and its F0 varied between 88 and 114.4 Hz across blocks. Sensitivity was significantly reduced in the presence of the interferer, and this effect decreased as its F0 was moved progressively further from that of the target. Experiment 2 showed that increasing the level of a synchronously gated lowpass noise that spectrally overlapped with the interferer reduced this "pitch discrimination interference (PDI)". In experiment 3A, the target was filtered between 3900 and 5400 Hz and had an F0 of either 88 or 250 Hz. It was presented either alone or with an interferer, filtered between 1375 and 1875 Hz with an F0 corresponding to the nominal target F0. PDI was larger in the presence of the resolved (250 Hz F0) than in the presence of the unresolved (88 Hz F0) interferer, presumably because the pitch of the former was more salient than that of the latter. Experiments 4A and 4B showed that PDI was reduced but not eliminated when the interferer was gated on 200 ms before and off 200 ms after the target, and that some PDI was observed with a continuous interferer. The current findings provide an alternative interpretation of a study supposedly providing strong evidence for the existence of two pitch mechanisms.

Detection and F0 discrimination of harmonic complex tones in the presence of concurrent complexes

This study measured the level of target harmonic complex tones, relative to simultaneous concurrent harmonic or inharmonic maskers, necessary for (a) target detection and (b) discrimination of the target F0. Depending on the condition, the F0 of the target was around 100, 200, or 400 Hz and the average F0 of the masker was either equal to this or 7 semitones lower or higher. Target and maskers were bandpass filtered between 1200 and 3600 Hz (48-dB/octave slopes). Low-pass noise masked distortion products. Masked thresholds in the target-detection task were generally higher when the average F0 of the masker was lower than that of the target, and were also higher for inharmonic than for harmonic maskers. In the F0 discrimination task, average F0 differences between the target and masker tones consistently improved masked thresholds at the highest F0 used (400 Hz) but not the lowest (100 Hz). Temporal asynchronies between the target and masker and reduced masker–F0 uncertainty had similar effects. These results suggest that peripheral frequency resolution may limit the ability to benefit from auditory segregation cues for both the detection and discrimination of harmonic complex tones embedded in other tones. [Work supported by NIDCD R01DC05216.]

Tone nucleus modeling for Chinese lexical tone recognition

This paper presents a new scheme to deal with variations in fundamental frequency (F0) contours for lexical tone recognition in continuous Chinese speech. We divide F0 contour of a syllable into tone nucleus and adjacent articulatory transitions. We only use acoustic features of the tone nucleus for tone recognition. Tone nucleus of a syllable is assumed to be the target F0 of the associated lexical tone, and usually conforms more likely to the standard tone pattern than the articulatory transitions. A tone nucleus can be detected from a syllable F0 contour by a two-step algorithm. First, the syllable F0 contour is segmented into several linear F0 loci that serve as candidates for the tone-nucleus using segmental K-means segmentation algorithm. Then, tone nucleus is chosen from a set of candidates by a predictor based on linear discriminant analysis. Speaker dependent tone recognition experiments using tonal HMMs showed our new approach achieved an improvement of up to 6% for tone recognition rate compared with a conventional one. This indicates not only that tone-nucleus keeps important discriminant information for the lexical tones, but also that our tone-nucleus based tone recognition algorithm works properly.

Simulations of cochlear implant hearing using filtered harmonic complexes: Implications for concurrent sound segregation and pitch perception

We studied concurrent sound segregation using cues similar to those available to cochlear implant listeners. Sixteen normally hearing subjects listened to mixtures of IHR sentences, processed using a simulation of implant hearing. Target sentences were bandpass filtered into six frequency bands between 1020 and 5000 Hz. The amplitude envelope in each band modulated a filtered, alternating-phase harmonic complex with F0=40 or 70 Hz. Each complex resembled a pulse train with pulse rate=2F0 and was filtered in the same way as the speech band that modulated it. The complexes consisted only of unresolved harmonics, whose pitch is processed in a way similar to that of electric pulse trains in implant hearing. The interferer was 3.5 s of time-reversed speech, processed in the same way as the target. After processing, targets were added to interferers at a 1.2-s delay, with SNR=9 dB. The target and interferer used complexes with either the same or different F0. Using a different F0 for the interferer benefited performance when the target F0=70 Hz, but had no effect when the target F0=40 Hz. Modifying the scheme by processing one sentence on only the odd-numbered channels and the other on the even-numbered channels impaired performance in all conditions.

Control of voice fundamental frequency in speaking versus singing.

In order to investigate control of voice fundamental frequency (F0) in speaking and singing, 24 adults had to utter the nonsense word ['ta:tatas] repeatedly, while in selected trials their auditory feedback was frequency-shifted by 100 cents downwards. In the speaking condition the target speech rate and prosodic pattern were indicated by a rhythmic sequence made of white noise. In the singing condition the sequence consisted of piano notes, and subjects were instructed to match the pitch of the notes. In both conditions a response in voice F0 begins with a latency of about 150 ms. As predicted, response magnitude is greater in the singing condition (66 cents) than in the speaking condition (47 cents). Furthermore the singing condition seems to prolong the after-effect which is a continuation of the response in trials after the frequency shift. In the singing condition, response magnitude and the ability to match the target F0 correlate significantly. Results support the view that in speaking voice F0 is monitored mainly supra-segmentally and controlled less tightly than in singing.

Fundamental frequency discrimination: Influence of lateralized temporal fringes

Fundamental frequency (F0) discrimination can be impaired substantially by the presence of another complex (the ‘‘fringe’’) immediately before and after the target complex. This has been attributed to listeners over-integrating information about the fringe F0 when estimating the target F0. It has been shown [C. Micheyl and R. P. Carlyon, J. Acoust. Soc. Am. (in press)] that for the impairment to occur (i) target and fringes have to be in the same frequency region; (ii) if all harmonics of target and fringes are unresolved then they may differ in F0; otherwise, they have to be similar. The present experiments investigated the effect of lateralized fringes. In a 2I-2AFC adaptive procedure, difference limens for F0 for a 100-ms harmonic target complex were measured in the presence and absence of 200-ms harmonic fringes. The nominal F0 was 88 or 250 Hz. Stimuli were bandpass-filtered between 125 and 625, 1375 and 1875, or 3900 and 5400 Hz. The target was presented monaurally, while the fringes were monaural (ipsilateral or contralateral) or binaural (diotic or dichotic, lateralized by ILD or ITD). Results showed reduced effects of fringes localized away from the target, the exact size depending on the resolvability of the components and their specific lateralization. [Work supported by Wellcome Trust.]