Pilot Tests with Adults
5.1 An Appropriate Phonological Context
As was shown in chapter 2, ACT is the primary phonetic correlate for the German laryngeal contrast between voiceless unaspirated and voiceless aspi-rated stops. The relevant parameter for categorical stop distinction in Swiss German is CD. The respective phonetic parameters for stop contrasts in German and Swiss German are perceptually distinguished best in different environments. Steriade (1997) describes ACT (VOT, in her wording) as a
‘contextual onset cue’, that is, a parameter realised at the beginning of the vowel that follows the stop under investigation. Accordingly, the German stop contrast is perceived best in stressed syllables where the stop is imme-diately followed by a vowel so that the voicing lag – be it long or short – can be realised and perceived well. The length cue in Swiss German requires an environment in which the onset of the closure phase can be identified.
Steriade (1997) defines CD as a parameter that is internal to the stop and which is realised before the release burst and potential onset cues. Thus, the ideal context to maintain the contrast in Swiss German is a position where the stop follows a vowel, so that the silent interval of the stop closure is in maximal contrast to the surrounding sonorant context. In both German and Swiss German it is essential that the stop is audibly released to make ACT and CD perceivable.
Hence, the environment in which the stops under investigation will be presented in the present experiments has to be selected carefully. As al-ready mentioned in chapter 2, the stop contrasts in both languages are best perceived in intervocalic position. However, passive voicing of the lax stops
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in word-medial (posttonic1) position often conceals the fact that German opposes phonetically voiceless unaspirated and voiceless aspirated stops. In this position, vocal fold vibration of the surrounding vowels is sometimes maintained throughout the closure phase of the lax stop. In the same con-text, tense stops often show a reduced voicing lag compared to word-initial stops. Consequently, the contrast in word-medial position sometimes ap-pears as a contrast of voiced versus voiceless stops – comparable to the laryngeal contrast as implemented in the Romance and Slavic languages – and not as a contrast of voiceless unaspirated versus voiceless aspirated stops, the contrast displayed in the majority of the Germanic languages.
In word-initial position, the laryngeal contrast is quite distinct since tense stops are strongly aspirated in this position. In this context, the Ger-man contrast of phonetically voiceless unaspirated versus voiceless aspirated stops is revealed best, without distortions caused by passive voicing. In Swiss German, on the other hand, it is more problematic to distinguish two stop categories in absolute initial position. According to Kraehenmann & Lahiri (2007, 2008), there is anarticulatory contrast between long and short stops.
In perception, however, singletons and geminates in phrase-initial position cannot be distinguished. This is attributed to the fact that, if a stop is produced out of complete silence, there is no perceptible starting point of the closure phase. The contrast between singletons and geminates is most distinct in intersonorant position, with the geminates closure phase being about thrice as long as that of the singletons (Kraehenmann 2001).
Word- or even phrase-final position is not an appropriate context for a comparison of the two languages, either. The contrast is maintained in final position of a word in Swiss German as the stops are audibly released and the differences in CD can be perceived. In German, however, the laryngeal contrast is neutralised to a voiceless unaspirated stop in word-final position (cf. chapter 2).
Apparently, the only appropriate context to compare the stop contrasts of German and Swiss German is in phrase-medial word-initial position, that is, an environment where the stops are preceded by an unstressed vowel and followed by a stressed vowel (V "V). The preceding vowel guarantees that the starting point of the closure phase is perceivable. The following vowel permits the realisation and perception of voicing lags; and since it is a stressed vowel there will be less passive voicing than in a context where
1Disyllabic content words, the most common context in which intervocalic stop con-trasts have been studied (e.g., Braunschweiler 1997; Kraehenmann 2003), are mostly trochaic in their foot structure, both in German and in Swiss German. Therefore, word-medial position is often associated with stops between a stressed and an unstressed vowel.
5.1 An Appropriate Phonological Context 117 the stop follows a stressed vowel. These considerations suggest that the best context to test the perception of German and Swiss German stops is one in which the stops are preceded by a schwa and followed by the full vowel /a/, as they occur in the German phrases Das sch¨onste Paar [tas "Sø:nsth@
"pha5] ‘the most beautiful couple’ and Die sch¨onste Bar [ti: "Sø:nsth@ "pa5]
‘the most beautiful nightclub’. In this context ([@ "a]), ACT as well as CD can be measured and perceived easily without strong secondary effects that might provide additional cues to the distinction, as for example word-medial passive voicing or effects of the length of a preceding stressed full vowel. As demonstrated by Braunschweiler (1997), full vowels tend to be longer before lax stops and shorter when preceding tense stops in German. /@/, which is always unstressed, is not prone to be affected by length differences much.
Thus, by choosing /@/, it can be avoided that the preceding vowel provides a secondary cue to the contrast, in addition to ACT and CD. /a/ is chosen as the following stressed vowel since it is the least marked, thus the most neutral vowel in the vowel inventories of both languages under investigation.2 Regarding the stops, exclusively labial stops are selected for investigation.
If present at all, vocal fold vibration is most distinct in labial stops (e.g., Mitleb 1981; van Alphen & Smits 2004). Aspiration, by contrast, is weakest in labial and strongest in dorsal stops (Volaitis & Miller 1992; also cf. section 8.2). By choosing labial stops, a bias in favour of aspiration and against voicing contrasts is avoided. Apart from that, word-initial /k/ is often realised as affricate[>
kx]or fricative[˚G]in Swiss German (Kraehenmann 2003;
Fleischer & Schmid 2006). Moreover, coronal stops often are assumed to show an exceptional phonological behavior due to underspecification (e.g., Friedrichet al.2006; Fikkert 2010).
The present chapter will report on two pilot studies conducted with adults. The first one (section 5.2) collects ACT and CD values in productions of precisely the context that will be tested in infants later. The second one (section 5.3) assesses adults perception of stops with different ACT and CD values in the same context.
2Note also that Braun (1996) remarks that there are no consistent results in terms of co-articulatory effects of the tongue height of following vowels across stops in different regions of Germany. She suggests instead that the quality of a following vowel affects ACT realisation only marginally and that it is less determining than the PoA of the stop.