Place assimilation
Cheyenne Munson, Bob McMurray, and David Gow
Certain sounds (those made with the tip of the tongue) undergo a lot of variation in running speech.
For example, the /n/ in green can be produced as (and sound like) an /m/ when it is adjacent
to other sounds that are produced with the lips (e.g. /b/). Thus, green boat can often be pronounced as
greem boat. The acronym NPR provides an example of this change occuring within-word—it is not uncommon
for NPR to be pronounced more as MPR, and it can even be difficult to avoid pronouncing it this way! However,
this transformation is typically not complete—the /n/ does not completely change into an
/m/. Rather, it has the articulatory and acoustic properties of both /n/ and /m/.
We also still understand it as an /n/.
This project examines how the perceptual system compensates for this variation and may even make use of it to predict upcoming words. We have assessed this hypothesis using an eye-tracking task. When listeners see a display like the one above and are told to select the green boat, we expect them to be faster to look to this object when green is assimilated. You can click on the sound files below to hear sentences in which green is unassimilated and assimilated. The difference is pretty small, but if you can hear the slight "m" sound at the end of the second green, that's the assimilation.
Unassimilated:
Assimilated:
Results indicate that listeners are faster to look at the target when they hear assimilated speech, so they are
indeed able to use acoustic detail to help them predict the upcoming word (or at least what sound it will begin
with). Different experiments in this project
are designed to test how listeners' lexical knowledge interacts with the process of word recognition and whether lexical competition slows the
facilitative effect provided by assimilation. Additionally, we are interested in the precise acoustic cues that
listeners are picking up on in assimilated speech.
Presentations:
Munson, C., & McMurray, B. (2007, October).
Perceptual features of place assimilation are continuous and contextually determined.
Poster presented at Where do Features Come From? Phonological Features in the Brain,
the Mouth, and the Ear. Paris, France.
poster
Munson, C., & McMurray, B. (2006, October).
Lexical and acoustic factors in progressive anticipation following perception of assimilated speech.
Paper Presented at the 12th Mid-Continental Workshop on Phonology. Iowa City, IA.
abstract
Munson, C., McMurray, B., & Gow, D. (2006, June).
Lexical influences on the progressive facilitation during perception of assimilated speech.
Paper Presented at the 151st Meeting of the Acoustical Society of America. Providence, RI.
abstract