Speaker: Peter Graff (MIT) http://web.mit.edu/graff/www/
Title: "Communicative Efficiency in Phonology"
Time: Friday Feb. 15th, 3pm.
Place: Sid Smith 560A (ground floor)
(Sid Smith is located at 100 St. George St.)
In this talk, I present novel typological and behavioral evidence
suggesting that phonological patterns derive from communicative efficiency:
The cross-linguistic patterning of sounds and words as well as the ways in
which speakers produce them are geared towards achieving a high rate of
information transmission given the effort invested by the speaker
(Lindblom, 1990; Flemming 1995).
First, I show for the first time that the relative occurrence frequencies
of different sounds in 60 languages from 25 major language families may be
understood in terms of communicative efficiency. Building on well-known
findings about the relative perceptibility of voicing contrasts in
different contexts (Raphael, 1981), differences in the effort involved in
articulating different voiced stops (Ohala & Riordan, 1979), and
information theory in the sense of Shannon (1948), I derive a measure of
communicative efficiency for frequency distributions over voiced and
voiceless stops in context. I show that the efficiency of natural language
frequency distributions over those categories is significantly greater than
expected from chance.
Next, I present evidence that redundancy in the lexicon is not randomly
distributed, but instead exists to supplement distinctions between
meaningful linguistic units that are hard to perceive. Specifically, I show
that the number of words disambiguated solely by a given contrast (i.e.,
minimal pairs) decreases as a function of the perceptibility of that
contrast, beyond what is expected from the probabilistic patterning of the
contrasting sounds. The lexicon as a whole is thus organized in ways that
minimize the confusability of words given the effort invested in their
Finally, I present behavioral evidence suggesting that language production
at the sound level seeks to maximize the rate of information transmission
and minimize speaker effort (cf Aylett & Turk, 2004). I report on a
phonetic corpus study of F2-transitions into stops and stop burst durations
showing that these acoustic cues to place of articulation stand in a
probabilistic trade-off relation. When stop bursts are long, F2-transitions
are correspondingly small, while when stop bursts are short, F2-transitions
are correspondingly large. This trade-off is expected if the articulatory
effort invested in the production of the burst is reduced where formant
transitions convey sufficient information for the listener to recover the
place of a stop.
Taken together, these results suggest that communicative efficiency shapes
human language phonology, the lexicon, and the ways in which humans use
sounds and words to communicate intended meanings.