Contour Mapping for Speaker-Independent Lip Reading System

In this paper, we demonstrate how an existing deep learning architecture for automatically lip reading individuals can
be adapted it so that it can be made speaker independent, and by doing so, improved accuracies can be achieved on a
variety of different speakers. The architecture itself is multi-layered consisting of a convolutional neural network, but if
we are to apply an initial edge detection-based stage to pre-process the image inputs so that only the contours are
required, the architecture can be made to be less speaker favourable.
The neural network architecture achieves good accuracy rates when trained and tested on some of the same speakers
in the ”overlapped speakers” phase of simulations, where word error rates of just 1.3% and 0.4% are achieved when
applied to two individual speakers respectively, as well as character error rates of 0.6% and 0.3%. The ”unseen speakers”
phase fails to achieve as good an accuracy, with greater recorded word error rates of 20.6% and 17.0% when tested on
the two speakers with character error rates of 11.5% and 8.3%.
The variation in size and colour of different people’s lips will result in different outputs at the convolution layer of a
convolutional neural network as the output depends on the pixel intensity of the red, green and blue channels of an input
image so a convolutional neural network will naturally favour the observations of the individual whom the network was
tested on. This paper proposes an initial ”contour mapping stage” which makes all inputs uniform so that the system can
be speaker independent.
Keywords: Lip Reading, Speech Recognition, Deep Learning, Facial Landmarks, Convolutional Neural Networks,
Recurrent Neural Networks, Edge Detection, Contour Mapping