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On the Boundaries of Phonology and Phonetics


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1.4.Clause typing


Dutch, like any other language, has lexico-syntactic means to express a range of clause types, such as statement, command, exclamation and question. Although the lexico-syntactic means are generally adequate and sufficient to express the speaker’s pragmatic intention to the hearer, several – if not all – clause types are supported by prosodic means, specifically by appropriate intonation patterns. In fact, exceptional situations may arise where there is no lexico-syntactic differentiation between the clause types, and where the speaker’s intention can only be recovered from melodic cues. For the purposes of the present experiment we have looked for a situation in which the three prosodic categories may serve as the only cue to a ternary choice among clause types, so that prosody will be exploited to the utmost, and the listener’s choice will not be co-determined by lexical and/or syntactic cues. Such a situation may be obtained in a V1 sentence, where the finite verb has been moved into the sentence-initial position.6 In the sentence Neemt u de trein naar Wageningen ‘Take you the train to Wageningen’ the lexico-syntactic information is compatible with at least three interpretations:7


  • A polite imperative (Kirsner, van Heuven & Caspers, 1998)

  • A conditional clause similar in meaning to ‘If you take the train to Wageningen ...’

  • A yes/no question ‘Do you take the train to Wageningen?’

Which of the three readings is intended by the speaker, is expressed through prosody only. In setting up the experiment we assumed that there is no principal difference in the speech melody between a statement and a command in Dutch.8 Using a range of terminal pitch patterns on the single phrase Neemt u de trein naar Wageningen, we can determine the category boundaries between command (for statement), conditional (for continuation), and question without any inter­fering differences in lexico-syntactic structure.



We may conclude this introduction by summarizing the research questions that we will address:


  1. Are the domain-final boundaries ‘L%’ ~ ‘%’ ~ ‘H%’ contiguous categories along a single tonal dimension?

  2. Is there a one-to-one correspondence between ‘L%’ and ‘command’, ‘%’ and ‘conditional’, and ‘H%’ and ‘question’?

  3. Where are the category boundaries – if any – along the continuum between (i) ‘L%’ and ‘%’ and (ii) between ‘%’ and ‘H%’?

  4. Are the category boundaries at the same positions along the stimulus range irrespective of the binary versus ternary response mode?

  5. Are both boundaries truly categorical in the sense that there are discrimination peaks for adjacent stimulus pairs straddling the category boundaries?

2.Methods

2.1.Stimuli


A male native speaker of standard Dutch read the sentence Neemt u de trein naar WAgeningen? with a single ‘H*L’ accent on the first syllable of Wageningen. The utterance was recorded onto digital audio tape (DAT) using a Sennheiser MKH 416 unidirectional condenser microphone, transferred to computer disk (16 kHz, 16 bits) and digitally processed using the Praat speech processing software (Boersma & Weenink, 1996; Boersma & van Heuven, 2001). The intonation pattern of the utterance was stylized by hand as a sequence of straight lines in the ERB x linear time representation. Nine intonationally different versions were then generated using the PSOLA analysis-resynthesis technique (e.g. Moulines & Verhelst, 1995; Rietveld & van Heuven, 2001: 379-380) implemented in the Praat software. The nine versions were identical up to and including the ‘H*L’ configuration on Wageningen. From that point onwards the nine versions diverged into two falls and seven rises. The terminal frequencies of the nine versions were chosen to be perceptually equidistant, i.e., the difference between any two adjacent terminal frequencies was equal in terms of the ERB scale.9 The terminal pitch of version 1 equaled 80 Hz, the increment in the terminal frequency for each following version was 0,25 ERB. The nine pitch patterns are shown in Figure 3.

F
igure 3
. Steps 1 through 9 along resynthesized continuum differing in terminal F0 by 0,25 ERB increments. Intensity contour (dB) and segmentation (by syllables) are indicated.

2.2.Tasks and experimental procedures


For the discrimination task, which was the first task imposed on the subjects, we followed Ladd and Morton (1997) in using the AX discrimination paradigm. Stimuli were presented in pairs that were either the same or one step apart on the continuum. In the latter case, the second can be higher or lower than the first (hereafter AB and BA, respectively). The eight AB stimulus types ran from pair {1,2} to {8,9}; the eight corresponding BA types from {2,1} to {9,8}. This yielded 9 identical pairs and 2 x 8 = 16 different pairs, which occurred in random order, yielding a set of 25 trials in all, which was presented to each listener four times in different random orders, preceded by five practice trials. Stimuli within pairs were separated by a 500-ms silence, the pause between pairs was 3000 ms. A short warning tone was sounded after every tenth trial.

For the identification task listeners responded to individual stimuli from the 9-step continuum by classifying each either in terms of a binary or a ternary choice:




  1. ‘Command’ ~ ‘no command’. In one task the listeners were instructed to decide for each stimulus whether they interpreted it as a command or not.

  2. ‘Question’ ~ ‘no question’. An alternative task involved the decision whether the stimulus sounded like a question or not.

  3. ‘Command’ ~ ‘condition’ ~ ‘question’. The third task was identical to the task imposed in van Heuven & Kirsner (2002).

Half of the listeners first performed task (1), the other half of the listeners began with task (2). Task (3) was always the last identification procedure in the array of tests. For each task, the set of nine stimuli were presented five times to each listener, in different random orders, and preceded by five practice items, yielding sets of 50 identification stimuli per task.

Twenty native Dutch listeners, ten males and ten females, took part in the experiment on a voluntary basis. Participants were university students or members of their families. None of them reported any perceptual deficiencies.

The experiments were run with small groups of subjects, who listened to the stimuli at a comfortable loudness level over Quad ESL-63 electrostatic loudspeakers, while seated in a sound-treated lecture room. Subjects marked their responses on printed answer sheets provided to them, always taking the discrimination task first and the identification tasks last.


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