F0 Lowering Research Articles

Post-focus compression in Brahvi and Balochi.

Previous research has shown that post-focus compression (PFC)- the reduction of pitch range and intensity after a focused word in an utterance, is a robust means of marking focus, but it is present only in some languages. The presence of PFC appears to follow language family lines. The present study is a further exploration of the distribution of PFC by investigating Brahvi, a Dravidian language, and Balochi, an Indo-Iranian language. Balochi is predicted to show PFC given its presence in other Iranian languages. Dravidian languages have not been studied for prosodic focus before and they are not related to any languages with PFC. We recorded twenty native speakers from each language producing declarative sentences in different focus conditions. Acoustic analyses showed that,in both languages, post-focus f0 and other correlates were significantly reduced relative to baseline neutral-focus sentences, but post-focus lowering of f0, and intensity was greater in magnitude in Balochi than in Brahvi. The Balochi results confirm our prediction, while the Brahvi results offer the first evidence ofPFC in a Dravidian language. The finding of PFC in a Dravidian language is relevant to a postulated origin of PFC, which is related to the controversial Nostratic Macrofamily hypothesis.

Interaction of prosody and syntax-semantics in Mandarin wh-indeterminates.

This paper reports on two speech-production experiments focused on Putonghua and Taiwan Mandarin sentence-final particles and wh-phrases that have interrogative or indefinite readings in three contexts: yes/no questions, wh-questions, and statements. Sentence-final particles were found to influence focus-prosody through right-edge shortening and lowering of F0 and intensity of wh-phrases, thus distinguishing wh-interrogatives from indefinites and questions from statements. Speakers adopt multidimensional acoustic strategies to shape intonation: while maintaining the lexical tones, prosody interacts with the organization imposed by syntax, semantics, and focus. The two varieties of Mandarin differ in the extent to which their prosodic differences represent such syntactic-semantic information.

Elicitation context does not drive F0 lowering following voiced stops: Evidence from French and Italian

Consonant-intrinsic F0 (CF0) effects are mainly the result of raising F0 following voiceless obstruents, rather than of lowering F0 following voiced obstruents. However, there are also documented instances where lowered F0 following voiced obstruents is enhanced. Given that both voicing and F0 are affected by prosodic context, it is possible that CF0 is lowered in some contexts but not others. This possibility is investigated by examining CF0 in French and Italian in isolated citation forms. Results are comparable to carrier-phrase contexts, where no F0 lowering after voiced obstruents is observed. Possible sources of the apparent cross-linguistic differences are discussed.

Tonal split and laryngeal contrast of onset consonant in Lili Wu Chinese.

This study examines the acoustic properties concerning tonal split and stop onsets in an under-documented Wu Chinese variety, Lili Wu, using speech production data collected from field research. Lili Wu Chinese has been reported to demonstrate an unusual tonal split phenomenon known as "aspiration-induced tonal split" (ATS). ATS refers to the distinct lowering of f0 of a lexical tone over syllables beginning with a voiceless aspirated obstruent, compared to that of syllables beginning with an unaspirated obstruent. Two debates lingering in the existing literature are discussed: (i) is ATS an on-going change or a completed change? and (ii) is it onset aspiration or vowel breathiness that directly triggers ATS? Results suggest that ATS is a completed change, which, however, is conditioned by tonal contexts. Regarding the second debate, results suggest that neither aspiration nor breathiness serves as the direct trigger for tonal split. Moreover, one unexpected on-going sound change was observed: The breathiness of vowels after voiced onsets seems to be disappearing among the younger generation. These findings extend the understanding of the acoustic properties of tonal development in a complex system and highlight the importance of experimental methods in understanding the sound structure and changes of under-documented languages.

Consonant-f0 interaction in Malayalam stops: Automatic or controlled?

Voicing is known to perturb f0 in the following vowel (House and Fairbanks, 1953). This lowering has been attributed to biomechanical constraints (Svantesson and House, 2006). On the basis of evidence from languages where the [voice] feature does not manifest itself phonetically, yet is accompanied by f0 lowering, it has been argued that f0 lowering serves to enhance the phonological [voice] contrast. We present results from an acoustic study of f0 perturbation in Malayalam, which exhibits predictable voicing in lexical items from its Dravidian stratum. Underlying voiceless stops only appear initially, and are voiced intervocalically. Malayalam also contains a large Sanskrit stratum lexicon, where phonetic voicing is tied to its stratal affiliation. We obtained a significant effect of laryngeal setting on z-score normalized f0 at vowel onset. These results suggest voicing is significant in determining the onset f0 of the vowel, regardless of the phonological status of voicing in a language We conclude that f0 lowering has physiological and biomechanical bases. In that sense, f0 lowering is an automatic consequence of the biomechanics of voicing. At the representational level, such lowering could indeed be enlisted for enhancement, however, that is not the only, or the primary purpose of f0 perturbation.Voicing is known to perturb f0 in the following vowel (House and Fairbanks, 1953). This lowering has been attributed to biomechanical constraints (Svantesson and House, 2006). On the basis of evidence from languages where the [voice] feature does not manifest itself phonetically, yet is accompanied by f0 lowering, it has been argued that f0 lowering serves to enhance the phonological [voice] contrast. We present results from an acoustic study of f0 perturbation in Malayalam, which exhibits predictable voicing in lexical items from its Dravidian stratum. Underlying voiceless stops only appear initially, and are voiced intervocalically. Malayalam also contains a large Sanskrit stratum lexicon, where phonetic voicing is tied to its stratal affiliation. We obtained a significant effect of laryngeal setting on z-score normalized f0 at vowel onset. These results suggest voicing is significant in determining the onset f0 of the vowel, regardless of the phonological status of voicing in a language We conclude tha...

Hejazi Saudi Arabic pharyngeal approximant 'Ayn involves 4 of 5 correlates of creak, but not positive H1-H2 spectral tilt

Five correlates of creaky phonation in the Arabic pharyngeal approximant 'Ayn—/ʕ/—were compared in speech samples of five male native speakers of the Hejazi dialect of Saudi Arabic to determine the degree to which creaky phonation could be a phonetic feature of 'Ayn. Jitter, shimmer, harmonics-to-noise ratio (HNR), F0 lowering, and positive H1-H2 spectral tilt were compared in 360 (total) speech tokens of /a/, /aa/, and /aʕa/ vowel sequences. Acoustic analysis indicated significantly increased jitter, increased shimmer, lower HNR, and lower F0 values in 'Ayn sequences compared to non-'Ayn sequences, yielding strong evidence of creaky phonation. There was, however, no significant increase in degree of positive H1-H2 spectral tilt in 'Ayn sequences compared to non-'Ayn sequences. Positive tilt appeared to occur in free variation across vowel sequence types with many non-'Ayn sequences displaying the positive H1-H2 spectral tilt traditionally associated with creak. If increased jitter, increased shimmer, lower HNR, and local F0 lowering are correlates of creak in these realizations of 'Ayn, we must consider that creak is a key phonetic feature of 'Ayn for these Arabic speakers and that positive H1-H2 spectral tilt may not be a reliable indicator of creak in Hejazi Arabic.

Interaction between aspiration and tonal pitch in Weihai Chinese

This paper considers the questions of whether, how, and by what mechanism the aspiration of voiceless stops in the syllable onset affects the pitch (F0) of lexical tone in a tone language. The literature on this topic is at odds with itself. Lai et al. [“The raising effect of aspirated prevocalic consonants on F0 in Taiwanese,” Proceedings of the 2nd International Conference on East Asian Linguistics (2009)] review the history of conflicting results, with some studies reporting F0 lowering after aspirated stops, and some reporting F0 raising. Here is provided another battery of findings from another tonal dialect, Weihai Chinese. Using data from seven monodialectal female speakers, no effect of aspiration is found on tonal F0 following bilabial or alveolar stops, but a strong significant lowering effect was observed following the velar aspirated stops. A second issue addressed here has had almost nothing published about it, viz., what is the converse effect of the lexical tone pitch upon the aspiration time (VOT) of the onset stops. It was found that, in general, high-beginning tones correlated with shorter voice onset times in all stop onsets.

Brain responses to spoken F0 changes: Is H special?

Across languages and linguistic phenomena, rises in spoken pitch seem to occupy a privileged position compared to steady F0 or pitch lowering. Speakers are more likely to use sudden rises in pitch to arouse listener attention, rather than using falls; e.g., contrastive stress, questions seeking a response, beginnings of units of discourse, expressions of intense emotion, etc. The study evaluated whether there are brain responses that are more sensitive to stepwise raised vs. lowered spoken F0, and whether any such responses were also caused by pure tone stimuli. Three types of brain response were evaluated. Mismatch negativity (MMN), which reflects pre-attentive mechanisms, was only sensitive to degrees of F0 change, and not to direction. P300, which is an indicator of attention orientation, did not show sensitivity to F0 direction to non­speech stimuli, but showed greater sensitivity to raised F0 than to lowered F0 in speech. Time–frequency analysis of EEG data showed beta-band response in the right parietal area, when presented with spoken F0 elevation. Taken together, the P300 and beta band results suggest that attention modulation mechanisms are triggered when listeners are exposed to sudden rises in spoken F0. However, there was a lack of attention orientation response when non-speech F0 changes were presented, or when subjects were exposed to lowering of F0 in speech.

Consonant-f0 interaction under predictable voicing: f0 lowering due to phonetic factors

We report on consonant-f0 interactions in Malayalam. Crosslinguistically, voicing lowers f0 in the following vowel (House and Fairbanks 1953, Hombert 1978, Clements 2002, Moreton 2006). While this lowering has been attributed to physiological and phonetic factors (Stevens 1998, Atkinson 1978, and Honda 2004), Ohde (1984), Svantesson and House (2006), and Keating (1984) have argued that f0 lowering serves to maintain a phonological contrast between voiced and voiceless segments. Voicing in Malayalam is predictable; voiceless stops appear initially, and voiced intervocalically. We report on data from 6 native speakers. 3 repetitions of each word in a frame sentence were recorded. Since Malayalam words only appear with voiceless initial stops, we contrast these with nasals from corresponding places of articulation. We examine time-normalized f0 perturbation due to voicing in Malayalam for all places of articulation for both initial and medial contexts. Our findings lend support to the physiological and phonetic account of f0 lowering. Malayalam exhibits a pattern of f0 lowering following voicing and raising during the production of voiceless segments. In spite of Malayalam voicing being predictable, the f0 perturbation in the following vowel follows the cross-linguistic pattern of lowering following voiced segments. This finding dove-tails with the results from earlier studies that take physiological factors to be responsible for the lowering of f0 following voiced segments.

Effects of prosodic position on the production of Si-Xien Hakka tones at phrase level

This study examined the effects of prosodic position on duration and F0 of the six tones in Si-Xien Hakka. Each of the tones was placed in the initial, medial, and final positions of a three-syllable phrase/clause, which constituted the first part of a sentence with the [δδδ, δδδ] structure. The results showed that F0 lowering and lengthening were found at domain final position. The final lengthening allowed the offset of the low-rising tones to reach a higher F0 target, not attainable by those in other prosodic positions. Also in this final position the high level tones exhibited a real flap shape due to the greater coarticulation resistance caused by the following boundary breaks. Furthermore, the F0 decreasing rate of the falling tones was found to vary according to domain position: the F0 descended the fastest at domain medial position and the slowest at final position, except for the high checked tones, which showed the same rate at domain-initial and –final positions. This reveals that the vibration of the vocal folds, reflected by the F0 decreasing rate, started from the initial position, gradually speeded up to the highest rate at medial position and then slowed down till the pre-boundary domain-final one.

Enhancement of laryngeal features under segmental and prosodic conditioning

Evidence in support of enhancement features (Keyser and Stevens, 2006) is presented from an acoustic study of laryngeal contrasts in Hindi. Segmental contrasts where defining features and their corresponding acoustic outcomes are attenuated are said to be made acoustically salient by enhancing gestural features (Stevens and Keyser, 2010). In this study, the four-way laryngeal contrasts in Hindi are examined under varying prosodic and segmental contexts. In segmental contexts where a defining distinctive feature (slack vocal folds) is attenuated in its acoustic manifestation, namely, closure duration (CD), an enhancing gesture (spread glottis) (Avery and Idsardi, 2001) is added to increase the saliency of contrasts between voiced aspirated stops (VAS) and voiced stops (VS). The acoustic consequence of this enhancement is f0 lowering in the following vowel. Similar results are obtained under weak prosodic conditions where both f0 lowering and increase in spectral tilt result from the enhancing gesture (spread glottis). In addition, in segmental contexts where gestural overlap compromises the feature (slack vocal folds), (spread glottis) by way of f0 lowering in the acoustic dimension enhances the laryngeal contrast between VAS and VS. These results lend support to the theory of enhancement as proposed by Stevens and Keyser (2010).

Laryngeal Dynamics of Pedagogical Taan Gestures in Indian Classical Singing

Vocal modulations characterize many styles of singing. Vibrato, trill, and trillo are some of the ornaments that Western classical singers use. Likewise, taan is one of the basic frequency modulations demonstrated by Hindustani Indian classical singers. The objective of this descriptive study was to discover the F₀ contour of taan; establish selected acoustic, aerodynamic, and glottographic characteristics of the taan gesture; and explore the pedagogical taan utterances demonstrated by a well-known singer and teacher. Exploratory. Fundamental frequency, alternating current (AC) glottal flow, and electroglottographic width measures were obtained for taan productions by the classical Indian singer and teacher who demonstrated taan rate variations based on his pedagogical approach. The structure of the taan gesture was found to be an F₀ lowering and rising (the "taan dip") followed by a relatively flat portion (the "taan superior surface"). Rate of the F₀ structure of the taan gestures ranged from approximately 1.65 to 3.41Hz, and the F₀ extent ranged from 1.87 to 2.21semitone (ST). As the rate of the taan gesture increased, the superior surface shortened, whereas the taan dip stayed relatively constant (ranging from 170 to 230 ms). AC flow was greater for the lowest frequencies of the dip and faster rates. The pedagogical taan gesture has a specific structure of an F₀ dip followed by a relatively flat F₀ portion that shortens as taan rate increases. The F₀ dip and extent are relatively robust across rate. The taan productions are voluntarily controlled, in contrast to vibrato productions.

Spectrotemporal and f0 evidence for a theory of enhancement

According to Keyser & Stevens, 2006, apart from universal features that are utilized to calculate motoric instructions, there is a second parallel and language-specific process called enhancement, where additional motoric instructions are processed for the enhancement of the saliency of features that are in danger of being obliterated. The "Standard View" on the distinction between voiced stops (VS) and voiced aspirated stops (VAS) in Hindi proposes that the breathy-murmured release following VAS is sufficient to make the contrast between the VS and VAS (Ladefoged & Maddieson, 1996). Hence, audible distinctions between VAS and VS during closure (CD/VLT) are not relevant in maintaining the contrast. Results from our studies show that CD is a relevant cue in making a distinction between aspirated and unaspirated stops. Spectral intensity measures show that speakers employ different glottal configurations to obtain the breathy/modal voicing contrast. VLT durations are inversely correlated with f0, such that longer VLT for VAS leads to further lowering of f0. This evidence suggests that f0 perturbations, differences in the durations of closure, and nature and extent of aspiration, all contribute in making the four-way stop contrast possible in Hindi, in support of a theory of enhancement.

Some acoustic cues in the detection of the Nepalese aspiration

In terms of laryngeal setting, most languages have only two types of stops. In the Nepalese sound inventory there are four types of stops: voiceless unaspirated, voiced unaspirated, voiceless aspirated, and voiced aspirated (or breathy voiced). The main objective of this paper is to present the prominent and consistent acoustic cues that differentiate the aspirated segments from their unaspirated counterparts of the Nepalese coronals - the dental-alveolar (t,th,d,dh), retroflex (T,Th,D,Dh) and affricates (ts,tsh,dz,dzh). VOT (Voice Onset Time) (Lisker and Abramson 1964) is the familiar model used to characterize three of these phonation types - voiced, voiceless, and aspiration stops. Some authors have pointed out that this method is not able to distinguish the plain voiced and voiced aspirated stops. An alternative segmentation model proposed by Mikuteit and Reetz (2007) is adopted here. Beside the analysis of the closure duration of segments, measuring the beginning of the burst or its release, we use other acoustic cues to characterize Nepalese aspiration such as F0 lowering, the structure of the lower harmonics and spectral tilt (Hanson 1997, Stevens 1998). This experimental work is based on the corpus based on four native speakers of Nepali.

Normalizing pitch variability in intoxicated speech

Intoxicated speech studies have shown mixed results with respect to prosodic characteristics. Both an overall F0 rise [Hollien et al., J. Acoust. Soc. Am. 110, 3198–3206 (2001)] and F0 lowering [Johnson et al., Phonetica 47, 215–237 (1990)] have been observed under intoxication. These conflicting findings may be due to increased F0 fluctuations at various levels of intoxication and use of inconsistent prosodic domains, such as averaging over entire sentences or utterances. If phonetic analysis takes into account prosodic boundaries, then models will account for appropriate prosodic rises and falls [Taylor, J. Acoust. Soc. Am 107, 1697–1714 (2000)]. This paper reports an analysis of recordings of both intoxicated and control subjects. Speech samples are analyzed at sober and three lev-els of intoxication. Of particular interest are the prosodic patterns at the often unreported descending limb of intoxication, which displays the widest range of variability in behavior. Use of F0 parameter extraction, stylization, and rotation methods over appropriate prosodic domains factors out spurious variation at different intoxication levels. Evaluation of this normalization procedure is reported with respect to both within- and across-subject variation. Implications for the analysis of normal, intoxicated, and disordered speech are discussed.

The effect of [h] on tonal development in Nahuatl

In both its classical and modern forms, Nahuatl is usually described as having penultimate accent (with little discussion as to whether this is a phrase- or word-level phenomena). However, some varieties of Mexican Guerrero Nahuatl have recently been described as having word accent in locations related to the position of a historical non-word-final coda *h. Here, the hypothesis is investigated that coda *h lowered the fundamental frequency (F0) of the tautosyllabic vowel and that a H−L pitch contour was subsequently incorporated into the lexical representation of the word as *h was weakened and lost. Recordings were made of four dialects at varying stages of *h loss and tonal innovation. Six speakers from each dialect were recorded producing words in phrase medial and phrase final positions, some with historical coda *h and some without, and the F0 of each syllable in these words measured. The results indicated that the new accentual patterns found in some dialects have their origin in the phonetic lowering of F0 in syllables containing coda *h. It also seems that once a new accentual pattern is developed and the *h lost, the resulting phonologized pattern may not correspond to the phonetic locus of the sound change.

Effects of aspiration on fundamental frequency in Taiwanese syllables

The perturbation effect on vowel fundamental frequency (F0) by voiceless aspirated and unaspirated prevocalic obstruents is investigated in Taiwanese. It is well known that F0 is significantly higher after voiceless than voiced stops. However, the perturbation effect caused by aspiration has received much less attention. Twenty-eight minimal pairs contrasting in prevocalic aspiration across three different places of articulation from seven tonal categories in Taiwanese were recorded from two male and two female speakers. An acoustic study was conducted on a total of 1120 syllables. Onset, offset, and mean F0 as well as contours of the tones after the aspirated and unaspirated obstruents were compared. Results indicate that the onset and mean F0 are significantly higher when following aspirated obstruents but no difference was found in offset F0. Tonal contour comparison shows that the F0 raising effect triggered by aspirated obstruents disappears at 50–60<th>% of the tone. Higher larynx and faster airflow rate are posited as the major factors for the higher F0 after voiceless aspirated obstruents. The present results warrant a reconsideration of the traditional theory of aspiration-induced tonal split according to which a tonal split resulted from the lowering of F0 due to aspiration.

Role of vertical larynx movement and cervical lordosis in F0 control.

The role of vertical larynx movement in vocal frequency (F0) change has attracted the attention of many researchers. Recently, Hirai, Honda, Fujimoto, and Shimada (1994) proposed a mechanism of F0 control by vertical larynx movement based on the measurement of magnetic resonance images (MRI). In F0 changes, the larynx moves vertically along the cervical spine, which displays anterior convexity (lordosis) at the level of the larynx. Therefore, the vertical larynx movement results in the rotation of the cricoid cartilage and vocal fold tension changes. The present study reexamines the above mechanism based on a qualitative analysis of midsagittal MRI data using three male subjects with evident cervical lordosis. Tracings of the jaw, hyoid bone, laryngeal cartilage, and cervical spine were compared in high and low F0 ranges. In the high F0 range, the hyoid bone moved horizontally while the larynx height remained relatively constant. In the low F0 range, the entire larynx moved vertically, and the cricoid cartilage rotated along the cervical lordosis. These results indicate that the vertical movement of the larynx comprises an effective F0 lowering mechanism, and suggest that the human morphologies of low larynx position and spinal curvature contribute to voluntary use of the vocal function.

On the mechanism of lowering the voice fundamental frequency in the production of tones of Standard Chinese

While it is well known that the cricothyroid (CT) muscle is mainly responsible for lowering the voice fundamental frequency (F0) in many languages, the mechanism for F0 lowering in languages such as Standard Chinese (SC) has not been elucidated. Although several studies have shown that the sternohyoid (SH) muscle activity is strongly correlated with F0 lowering in SC, the mechanism itself is not clear since SH is not directly attached to the thyroid cartilage, whose movement is essential in changing the length and tension of the vocal chord. On the basis of an earlier finding on the production of Thai tones [D. Erickson, Annual Bulletin No. 27, RILP, Univ. Tokyo, pp. 135–149 (1993)], the present author has suggested the active role of the thyrohyoid (TH) muscle in F0 lowering in languages such as SC and Swedish [H. Fujisaki, Proc. XXIII World Congress of the International Association of Logopedics and Phoniatrics, pp. 156–159 (1995)]. The present study shows the detailed mechanism for F0 lowering involving both TH and SH in the production of the second, third, and fourth tones of SC based on new electromyographic observations.

Effects of discourse structure on F0 in Japanese: Raising versus lowering

Previous studies on English and other languages have shown that discourse structure has an influence on the intonation of a string of sentences or phrases. With respect to fundamental frequency in particular, both discourse-initial raising of F0 and final lowering effects have been reported. The present study examines whether discourse structure also influences intonation in Japanese, and if so, to what extent initial raising and final lowering interact to cue structure. Hierarchically organized discourses were constructed in which the target sentence position was varied. These short discourses were recorded by native speakers of Tokyo Japanese, and the fundamental frequency contours of the target sentences in each position were compared. Results indicate that there is a robust raising effect on discourse-initial phrases, as reported for other languages. The degree of raising is determined by an interaction between distance from the start of the utterance and pitch range. In contrast, there is little effect of lowering on discourse-final phrases. The few phrases that did show an effect suggest that syntactic structure may interact with the lowering process.