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II. Experimentation in Phonology
No claims in phonology are above doubt: the existence of the phoneme,
syllable, or the feature [voice]; the reconstructed Proto-Indo-European form for
Sanskrit budh-; that speakers know the posited rule-governed phonological
link between the pair of words repose/ repository. All of the ses are
potential subjects for experimental study. It is a matter of research strategy,
the availability of reliable experimental methods, and the amount of personal
commitment we have to one belief or another which determines which issues one
chooses to address experimentally. So many experimental paradigms have been
proposed for testing phonological hypotheses. I give representative examples
from different domains in phonology.
i.
Experimental Assessment of the Distinctive Feature of Speech
One of the most fundamental tasks of phonology is to establish how different linguistic messages are conveyed by sound. Whether it is lexical differences or grammatical function, distinct messages must have distinct physical encodings, whether these are paradigmatic (different ciphers from a finite inventory of ciphers) and/or syntagmatic (different permutations of the ciphers). This is far from a trivial issue and certainly not one to be determined unequivocally by the unaided ear. Well-established methods exist for discovering the physical correlates of different linguistic messages in cases where they are uncertain or disputed.
Consistent
differences may be sought in the physiological or acoustic domains but the
relevance of any difference found must ultimately be validated in the perceptual
domain (Lehiste 1970). For example, in a series of instrumental and experimental
studies, Lisker and Abramson (1964, 1967, 1970) found that in initial position
(before stress), the distinction between pairs of English words like paid
vs. bade, tie vs. die, cool vs.
ghoul, is carried largely by the
relative timing of voice onset after the stop release, that is, what is called VOT
(for Voice Onset Time): the phonemes /p t k/ showed a substantial delay in
VOT (modal VOT = 50¡X70 msec) whereas /b d g/ had a short VOT (modal VOT =
0¡X20 msec). Phonetically, this contrast is said to be between voiceless
aspirated stops and voiceless unaspirated stops. Perceptual studies demonstrated
that VOT was the dominant cue for such lexical distinctions although several
secondary cues also played a role (Lisker 1986). Although this contrast among
stops is commonly attribute d to presence vs. absence of voice, voicing per
se plays only a secondary role in this environment and in other positions in
the word as well (Denes 1955; Raphael 1972). Lisker (1957) showed that in
intervocalic position, in addition to voicing, the duration of stop closures
helps to cue lexical distinctions such as rapid
vs. rabid, where the voiceless
stop is longer.
The
stops that appear in prevocalic clusters after Is!,
e.g., spade, sty, school, may only
be voiceless unaspirated. Lotz et al. (1960) showed that to English speakers
these are perceptually most similar to the stops in bade, die, and ghoul, i.e.,
/b d g/ (though they are not completely identical, Caisse 1981). Thus, although
traditionally the prevocalic stops in paid
and spade would be counted as
allophones of the same phoneme / p / in English, there is greater physical and
perceptual similarity between the stops in bade
and spade.
ii.
Can Phonetically Different Sounds Be Psychologically the Same?
This
still leaves open the question of whether native speakers regard the voiceless
unaspirated stops in sC- clusters to
be psychologically similar to the voiceless aspirated or the voiceless
unaspirated in absolute initial position. This question was investigated by
Jaeger (1980, 1986) who used the so-called concept formation method to address
the question of the assignment of allophones to the /k/ phoneme. Without being
given any more instructions than (approximately) ¡§assign the following words
to two different categories depending on the pronunciation at their
beginning,¡¨ linguistically naive subjects were first presented orally with
uncontroversial examples with initial stops such as kiss,
chasm, cattle, and quake designated
¡§category,¡¨ intermixed randomly with noncategorv examples, grip, gash,
lime, ceiling, chest, and knife. Initially
subjects were given feedback on each trial, i.e., they were told whether their
category assignment was correct or not. If they reached some preset criterion of
performance in this training, they were then presented with words containing the
stop allophone whose phoneme membership was controversial, such as school
and scold. This time there was no feedback. If they put these words in
the same category as cool and cold
it would imply that they regarded the [k] and [kh] as somehow
psychologically equivalent. In fact, this is what they did. (See also Ohala
1986.)
iii.
Experiments on Morpheme Structure Constraints
Esper (1925) explored the effect of analogy on the change in phonological shape of words and morphemes. His experiment was a task where he required his subjects to learn the names of 16 objects, each having one of four different shapes and one of four different colors. (He trained them on 14 object-name associations but tested them on 16 in order to see if they could generalize what they learned.) In three different experimental conditions, each with a different group of subjects, the relationship between the names and properties of the objects differed.
The names presented to subjects in group I
were of the sort naslig,
sownlig, nasdeg,
sowndeg, where nas- and sown
coded color and -lig and -deg
coded shape (though they were not told of their ¡§morphemic¡¨
constituents). Since these names consisted of two phonologically legal
morphemes, this group could simplify their task by learning not 16 names but 8
morphemes (if they could discover them) plus the simple rule that the color
morpheme preceded the shape morpheme in each name. Group 3, a control group,
were presented names that had no morphemic structure; they had no recourse but
to learn 16 idiosyncratic names. As expected, group 1 learned their names much
faster and more accurately than group 3. Of
interest was the performance of group 2 which, like group 1, were presented with
bi-morphemic names and thus could, in principle, simplify their task by learning
just eight morphemes. But, unlike group 1, the rnorphemes were not
phonologically legal for English, e.g., nulgen,
nuzgub, pelgen,
pezgub
(where now nu- and pe- were color morphemes and -lgen
and
Esper¡¦s
experiment achieved his goal of showing the force of analogy in language change,
i.e., paradigm regularization, but it also demonstrates the psychological
reality of morpheme structure constraints.
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iv.
Experiments on Phonological Change
One
of the earliest accomplishments of phonology was the development of a method,
the comparative method, which allowed one to reconstruct the history of
languages, in particular the changes over time in the phonological forms of
words (Rask 1818; Grimm 1322). To oversimplify, the comparative method consists
in finding an optimal single unbranching path between pairs or groups of words
judged to be cognates, where the ¡§path¡¨ consists of (a) intermediate forms
between the two, one of which is the ¡§parent form¡¨ and (b) sound changes
which operate unidirectionally and convert the parent form into the attested
daughter forms. Historical phonology might seem at first to be an unlikely
domain for experimentation since most of the events of interest occurred in the
inaccessible past and thus cannot be manipulated by the experimenter. But if one
is willing to make the unformitarian assumption, that is, that
whatever caused sound changes in the past is still present and causing sound
changes now, then although we cannot be there when Proto-IndoEuropean kw
changed to Greek p, e.g., PIE ekwos ¡§horse¡¨
> Gk. hippos, we may be able to contrive circumstances where the
same or similar changes occur in front of our eves or our microphones. In fact,
the parallelism between diachronic and synchronic variation has often been
remarked by researchers and sometimes has led to laboratory-based studies of
sound change (Rousselot 1891; Haden 1938). One of the most fruitful areas of
experimental phonology, then, involves studies on the phonetic influence on
sound change or on phonological universals in general (see, e.g., Lindblom
1984; Wright 1986; Kawasaki 1986; Kawasaki-Fukumori 1992; Stevens 1989;
Goldstein 1983; Ohala 1992, 1993).
One of the most common processes evident in sound change is assimilation and one of the common textbook examples of it is the case of medial heterorganic clusters assimilating in Italian: Late Latin octo> Italian otto ¡§eight¡¨. Such assimilations are overwhelmingly of the form -C1C1- > -C2C2-; rarely does C2 assimilate to the place of C1 (and many of these cases could be reanalyzed as involving a different process; see Murray 1982). Such a change is usually attributed to ease of articulation or conservation of energy (a heterorganic cluster requiring more energy than a homorganic one). But if so, why is it C1 that usually changes, not 02 Expenditure of articulatory energy is presumably cumulative through an utterance and thus would be greater by the time C2 was reached than C1. Thus we might expect C2 to assimilate to C1, just the reverse of what is found. Such doubts lead us to entertain an alternative explanation for this process.
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v.
Experiments in Lexical Representation
Lahiri and Marslen-Wiison (1991, 1992) put underspecification
theory into the empirical arena. They suggested that the lexical representations
p05-ited by phonologists ¡§correspond, in some significant way, to the
listener¡¦s mental representation of lexical forms. . .and that these
representations have direct consequences for the way. . . the listener
interprets the incoming acoustic-phonetic information.¡¨ Lahiri (1991)
argued specifically that ¡§the surface structures derived after postlexical
spreading do not play a distinctive role in perception; rather, a more abstract
underspecified representation determines the interpretation of a phonetic
cue.¡¨
Ohala and Ohala (1993) attempted a replication of Lahiri and MarslenWilson¡¦s experiment,5 but restricted the subjects¡¦ responses to just one of two choices, e.g., when presented with an end-gated version of rube the choices specified on the answer sheet were room and rube. The results are seen ln figure 24.1 as triangles superimposed on the circles representing Lahiri and Marsien-Wilson. This curve appears to be quite similar to theirs, but there is a crucial difference: a statistical analysis is possible in the Ohala and Ohala case. In fact these results show that listeners made the correct identification of the stimuli up to the point where the consonant joined the vowel 82.8 percent of the time; this is highly significant (x2 = 92.03, 1 df, p < .001). Conversely, the same statistic shows that the subjects¡¦ choice of the incorrect CVN responses were much below chance level.
( Adapted from
John
J. Ohala. Experimental Phonology. The Handbook of Phonological Theory.
John A Goldsmith edition. 1996 )