Velarization of Russian labial consonants Kevin D. Roon1,2 and D. H. Whalen1,2,3 1 CUNY Graduate Center, 2 Haskins Laboratories, 3 Yale University [email protected], [email protected] ABSTRACT Most of the experimental work on velarization has relied on acoustic data [8, 9, 20, 21]. Investigations Contrast between palatalized and non-palatalized using articulatory data have been limited to consonants is a robust feature of Russian. Non- qualitative assessments of a small amount of data [4, palatalized consonants are generally viewed as 26] or few speakers [15]. An exception is a study by velarized (with secondary dorsal articulation) rather Litvin [18], which used ultrasound data [27] from 6 than “plain” (without secondary articulation). This speakers. Results from [18] contradicted the claims velarization has been proposed to play an important that velarization is a reflex of pharyngealization and role in the phonology of the language. The bases for that [s] lacks velarization since it is coronal [15]. velarization are transcriptions and acoustics, as well Litvin found that whether the dorsal gesture was velar as physiological data from liquids. There is little or uvular was segment-specific, and also concluded systematic articulatory investigation of whether that the dorsal gesture was inherent to the consonant consonants other than liquids are velarized. The since it was unaffected by the following vowel. Litvin present study used ultrasound data to determine looked only at [l] and the fricatives [f, s, ʂ, x], all whether there were identifiable dorsal articulations in word-initially. Since the realization of palatalization labial stops, fricatives, and nasals, both word-initially varies based on word position and manner [8], the and word-finally. We looked at labials to avoid realization of velarization may also depend on these confounding effects of other lingual targets. We factors. found that non-palatalized Russian labial consonants Velarization of non-palatalized consonants has have a velar constriction associated with them, been argued to play an important role in the irrespective of manner. We further found that the phonology of Russian [21], as in other languages [2]. tongue-dorsum gesture associated with labial The present study was therefore designed to add to consonants had a notable coarticulatory effect on the the findings from [18] by using ultrasound imaging of neighboring vowel. the tongue to determine whether there are identifiable dorsal gestures associated with non-palatalized labial Keywords: Russian, velarization, ultrasound consonants in Russian, across three different manners and in two different word positions. 1. INTRODUCTION 2. METHODS Russian has a robust contrast between palatalized and non-palatalized consonants across manner, primary The experiment was conducted in the Speech oral articulator, voicing, and word/syllable position, Production, Acoustics, and Perception Laboratory at in both stressed and unstressed syllables [11, 14, 16, the CUNY Graduate Center. The experiment was 21, 29]. It has been argued that Russian non- approved by the CUNY Institutional Review Board. palatalized consonants are in fact velarized [8, 9, 20, 21, 26, 30], i.e., they include a dorsal, velar gesture. 2.1. Participants There are differing claims as to the exact nature of this dorsal gesture, with some [21, 26] describing it as Three native speakers of Russian, all originally from Moscow and currently living in the New York City a full velar gesture similar to that associated with [ ], ɯ metro area, took part in the experiment: one 29-y.o. others [1, 17] describing it as a less extreme female, one 28-y.o. male, and one 32-y.o. male. All articulation, and still others [4, 11] claiming the speakers reported that they had no speech, language retraction noted in “velarization” is a reflex of a or hearing disorders, and provided informed consent. pharyngealization. Another claim is that the target [18] or presence 2.2. Procedure [17] of velarization depends on the particular segment or on the primary oral articulator [15]. It has also been 2.2.1. Stimuli claimed that secondary velarization is optional [16], though whether this optionality is within- or across- Stimuli consisted of 6 CVC syllables, shown in Table speaker is not stated explicitly. 1. The segments of interest in all stimuli were labial consonants: the stop [p], the fricative [f], and the nasal shotgun microphone, concurrently recorded both by [m], which appeared both word-initially and word- the Optotrak system at 44.1 kHz and by the video finally. Labial consonants were chosen since the capture card at 48 kHz. Optotrak data and ultrasound primary oral articulator does not involve the tongue, videos were synchronized based on the acoustics. so any observed regular gestures of the tongue would be unlikely to be attributable to the influence of some 2.2.3. Data quantification and analysis other lingual target. It has also been claimed [17] that the dorsal gestures associated with labials are less The following were identified and labelled by hand extreme than those of the liquid [l̴], so any positive based on the acoustic record using Praat [3]: the evidence for velarization of labial consonants would durations of each labial of interest (Table 1) and of be more compelling. To control for voicing, only the initial [a]s of the carrier phrase from the first ten voiceless obstruents [p, f] were used since word tokens, and the release of [p]s. The temporal midpoint position was manipulated in the experiment and of each segment (except [p]) was then calculated. voiced obstruents devoice word-finally in Russian Video frames corresponding to the midpoints and [11], and thus voiced obstruents could not be releases above were identified, and the surface of the compared across word positions. V was always [a]. tongue was traced by hand, using GetContours [28], with each contour being defined as a series of 100 xy Table 1: Stimuli. Real words in Russian are denoted pixel values. Contours were converted to mm and with an asterisk. Others are nonce words. head-corrected following [31]. While the contours were all defined in relation to a fixed head reference, Word-initial Word-final the coordinate system shown in the figures below is Stop pam map arbitrary and does not have an origin corresponding Fricative fam maf to any fixed anatomical point in the vocal tract. Nasal mat* tam* Problems with recording the Optotrak resulted in the loss of 10 tokens for speaker 2 (1 token each of [fam] Stimuli included real and nonce words, since it and [tam], 2 tokens of [pam], and 3 tokens of [mat] was not possible to construct CVC stimuli with only and [map]). One speaker produced 11 tokens of [pam] one or the other. Each Russian speaker produced all and [tam], and another produced 11 tokens of [tam]. of the target stimuli in the carrier phrase [a ɛtə ____] Smoothed cubic splines defined in Cartesian (‘and this is a ____ ’) presented on a computer screen coordinates were calculated for given groups of in Russian orthography. Each stimulus appeared ten contours along with 95% Bayesian confidence times, in randomized order. These stimuli were intervals for all groups using the gss package [10] in interspersed among a larger set of CVC stimuli that R [23]. Areas where the confidence intervals did not were collected for other experiments. overlap for at least 1 cm were interpreted as significantly different [6]. It has been argued [19] 2.2.2. Data collection that polar coordinates are more appropriate than Ultrasound images of the lingual articulation along Cartesian coordinates for calculating smoothed the midsagittal plane were recorded using an splines for tongue contours. However, polar Ultrasonix SonixTouch ultrasound machine. coordinates are appropriate when a virtual probe Speakers sat in a chair and placed their chin on the origin can be identified [12]. The identification of ultrasound transducer (C9-5/10 micro-convex), such a virtual origin is possible when the ultrasound which was held by a custom-made metal arm. The probe is stabilized relative to the participant’s head, transducer holder contained a spring that allowed for e.g., [25]. Since the present method relied on post-hoc movement of the jaw during speech. The display of head correction of the contours rather than head the ultrasound machine was streamed to a PC and stabilization, the identification of a single origin captured at 59.9402 Hz with an video capture card corresponding to the probe was not appropriate, and using a lossless codec (Magic YUV). An Optotrak thus Cartesian coordinates were used. Certus system was used to track the position of 3. RESULTS transducer holder and each speaker’s head so that the data could be corrected in post-processing for The first comparison was of the tongue shapes of the movement of the speaker’s head relative to the labials within word position, for a total of 18 transducer. The movement of the transducer holder comparisons (3 segments x 2 word positions x 3 was tracked with infrared markers, and each speakers). There were only six significant differences speaker’s head movement was indexed using four between any two segments: a section of infrared markers: one at the nasion and three on the approximately 1 cm the middle of the tongue contours forehead [24]. Audio was captured using a Sennheiser Figure 1: Cubic spline fits of tongue contours with the same word-initially for speakers 2 and 3, though 95% Bayesian confidence intervals for word-initial speaker 1 had no differences between word-initial (gold) vs. word-final (red) labials [p, f, m], for labials and the following [a]. speaker 2. However, two aspects of the differences shown in Figure 2 cast doubt on whether these differences were attributable to a velar gesture being associated with the labials but not with [a].