Variation and assimilation in German - Institut für Phonetik

536 COENEN, ZWITSERLOOD, AND BOÈLTE
(e.g., honey) or a semantic associate of that word (e.g., bee). Minimal
mismatch, in terms of phonological features, does not completely preclude
lexical access (Bölte & Coenen, 2001; Connine et al., 1993). All these
experiments used prime stimuli presented in isolation, and did not
distinguish between naturally occurring, regular variations and accidental
mispronunciations.
A frequent type of regular variation is assimilation. In connected speech,
speech segments can assimilate to adjacent segments, such that hot bath
can be produced as a hopbath. 1 Stated in terms of phonological features, the
segment [t] can lose its own (coronal) place of articulation and adopt the
(labial) place of the following segment [b]. Three issues are important
here. First, assimilation is context-dependent , that is, it only occurs in the
presence of an adjacent segment that triggers—or licenses, in speech
perception terms—the change. Thus, hot will only be pronounced as hop
when followed by a word starting with a labial (e.g., bath), not when
followed by words whose rst segments have another place of articulation
(e.g., gruel). Second, not all features can undergo assimilation. To stay with
our example of place assimilation: Coronal segments (e.g., [t], [d], [n]) can
legally change to labial ([p], [b], [m]) or velar ([k], [g], [ng]). However,
labial or velar segments never adopt a coronal place of articulation
(Kohler, 1995). We will thus label such changes illegal. Third, assimilation
is often not complete. Complete assimilation with a change in phoneme
status ([t] ! [p]) does indeed occur, but often changes are graded, with
traces of the original place of articulation present in the signal (Gow, 2000;
Nolan, 1992).
Assimilation, as a phenomenon in speech production, has important
implications for speech perception and word recognition. Perception
models which incorporate a more or less abstract specication of the sound
structure of words have to deal with deviations between the input and
lexical specications. A theoretically relevant issue concerns the legality of
such deviations. Whereas legal and naturally occurring changes should be
tolerated by such models, this must not be so for other deviations.
To add to a growing body of evidence, we investigated regular variation
in German, typically present in fast and informal speech, comparing
regular variation to other deviations that do not occur naturally. A range
of factors relevant to assimilation was investigated within the same study.
First, we contrasted legal changes such as coronal-to-labial (as in a hopbath)
with illegal changes, such as labial-to-coronal (as in totdrawer for top
drawer). Second, we investigated the context-dependenc y of assimilation,
by contrasting contextually appropriate and inappropriate changes
1 In the examples, legal and contextually appropriate assimilation will be marked by an a .
All other changed words were pseudowords.