Thesis: Speech Perception & Connectionsim

[Gareth]

(Sorry - ignore the previous message, I sent the wrong
file!)

FTP-host: archive.cis.ohio-state.edu (128.146.8.52)
FTP-filename: /pub/neuroprose/Thesis/gaskell.thesis.ps.Z

A new PhD thesis (150 pages) is now available in the 
neuroprose archive.  The thesis examines the role of 
phonological variation in human speech perception using both 
experimental and connectionist techniques.

Abstract:

The research reported in this thesis examines issues of word 
recognition in human speech perception.  The main aim of the 
research is to assess the effect of regular variation in speech on 
lexical access.  In particular, the effect of a type of neutralising 
phonological variation, assimilation of place of articulation, is 
examined.  This variation occurs regressively across word 
boundaries in connected speech, altering the surface phonetic 
form of the underlying words.  Two methods of investigation 
are used to explore this issue.  Firstly, experiments using cross-
modal priming and phoneme monitoring techniques are used to 
examine the effect of variation on the matching process between 
speech input and lexical form.  Secondly, simulated experiments 
are performed using two computational models of speech 
recognition: TRACE (McClelland & Elman, 1986) and a simple 
recurrent network.

The priming experiments show that the mismatching effects of a 
phonological change on the word-recognition process depend 
on their viability, as defined by phonological constraints.  This 
implies that speech perception involves a process of context-
dependent inference, that recovers the abstract underlying 
representation of speech.  Simulations of these and other 
experiments are then reported using a simple recurrent network 
model of speech perception.  The model accommodates the 
results of the priming studies and predicts that similar 
phonological context effects will occur in non-words.  Two 
phoneme monitoring studies support this prediction, but also 
show interaction between lexical status and viability, implying 
that phonological inference relies on both lexical and 
phonological constraints.  A revision of the network model is 
proposed which learns the mapping from the surface form of 
speech to semantic and phonological representations.

To retrieve the file:

ftp archive.cis.ohio-state.edu
login: anonymous
password:<email address>
ftp> cd /pub/neuroprose/Thesis
ftp> binary
ftp> get gaskell.thesis.ps.Z
ftp> bye
uncompress gaskell.thesis.ps.Z
lpr gaskell.thesis.ps [or whatever you normally do to print]

Gareth Gaskell
Centre for Speech and Language,
Birkbeck College,
London,

g.gaskell at psyc.bbk.ac.uk