I have over forty years experience in speech technology R&D, and much of my research
has been based on insights derived from human speech perception and production. I
built my first automatic speech recogniser - EARS (Electronic Apparatus for Recognising
Speech) in 1972, and in the mid-1970s I introduced the Human Equivalent Noise Ratio
(HENR) - a vocabulary-independent measure of the goodness of an automatic speech
recogniser based on a computational model of human word recognition. In the 1980s,
I published HMM Decomposition - a powerful method for recognising multiple simultaneous
signals (such as speech in noise) based on observed properties of the human auditory
system. During the 1990s and more recently, I've continued to champion the need
to understand the similarities and differences between human and machine spoken language
Since joining Sheffield I've embarked on research that is aimed at developing computational
models of Spoken Language Processing by Mind and Machine, and I'm currently working
on a unified theory of spoken language processing called PRESENCE (PREdictive SENsorimotor
Control and Emulation). PRESENCE weaves together accounts from a wide variety of
different disciplines concerned with the behaviour of living systems - many of them
outside the normal realms of spoken language - and compiles them into a new framework
that is intended to breath life into a new generation of research into spoken language
processing, especially for Autonomous Social Agents and Human-Robot Interaction.
At the more practical end of the scale, I’m involved in collaborations aimed at Clinical
Applications of Speech Technology (particularly for individuals with speaking difficulties)
and I'm becoming increasingly involved in Creative Applications of Speech Technology
through interactions with colleagues from the performing arts.
PRESENCE is a new architecture for speech-based interaction that is founded on the
premise that future progress depends, not on how to "bridge the gap" between speech
science and speech technology, but on both communities seeking to assimilate wider
research findings on the behaviour of living systems in general and the cognitive
abilities of human beings in particular. PRESENCE intentionally blurs the distinction
between the core components of a traditional spoken language dialogue system and,
as a result, cooperative and communicative behaviour emerges as a by-product of an
architecture that is founded on a model of co-action in which the system has in mind
the needs and intentions of a user, and a user has in mind the needs and intentions
of the system.
In pursuing PRESENCE-based approaches to modelling spoken language, I've become increasingly
drawn into studying vocalisation in general, whether it is performed by human beings,
animals or robots. I'm currently developing synthesisers for mammalian, insect and
dolphin vocalisations, and embedding them in behavioural simulations implemented
in Pure Data and in real-time embodiments using e-puck, Create and RoboKind robots.
My aim is to demonstrate that many of the little-understood paralinguistic features
exhibited in human speech (including emotion) are derived from characteristics that
are shared by living systems in general. Modelling such behaviours in this wider
context should eventually enable us to implement usable and effective interaction
with artificial intentional agents such as robots.
The use of technology to manipulate and alter human or machine voices interest me
greatly, and I’m particularly keen to use such techniques to create voices for animated
agents and robots that are ‘appropriate’ to their visual and behavioural affordances.
I'm also becoming increasingly involved in using such manipulations to explore more
creative possibilities, and I’ve recently enjoyed very productive interactions with
colleagues from the performing arts. In particular I work closely with Dr. Chris
Newell based at the University of Hull. As well as pursuing various collaborative
projects, Chris and I are slowly compiling a book entitled The Art of Artificial
Voices in which we explore the creative uses of spoken language from both the technological
and the performance perspectives.
One of the areas in which advanced speech technology algorithms can really make a
difference to people is in situations where individuals have serious difficulties
in hearing or speaking. The Sheffield Speech and Hearing group has a long history
of research in this area, and has devoted significant effort to developing assistive
technology that is tailored to the needs of specific individuals, such as dysarthric
speakers with cerebral palsy or laryngectomy patients. My research is focused on
the development of low-dimensionality speech synthesis and how to optimise real-time
control for users with severe motor impairment. I’m currently working on an articulatory
synthesiser (based on an acoustic waveguide model of the human vocal tract) which
incorporates a novel, yet anatomically parsimonious, tongue.
EUCog: European Network for the Advancement of Artificial Cognitive Systems (EU FP7
META-NET: Multilingual Europe Technology Alliance (EU FP7 Network)
Much of my personal research (and teaching) is performed using the Pure Data (Pd)
dataflow programming language. Pd provides a real-time graphical programming environment
(authored by Miller Puckette – “The diagram is the program”) that is designed to
operate on audio, graphical and video signals. Pd is a free alternative to Max/MSP,
and not only does it make it easy to implement real-time audio input/output, but
it is especially efficient for rapid prototyping and creative research. Go to my
Pd downloads page >>
Having been actively involved in speech technology R&D for over four decades, I’m
often called upon to deliver my personal perspective on the progress that’s been
made in the past and the prospects we’re likely to witness in the years to come.
In order to inform these views, I’ve not only conducted a number of surveys of the
speech technology R&D community, but I’ve also exploited the ability of my Human
Equivalent Noise Ratio (HENR) model to extrapolate automatic speech recogniser performance
into the future. In addition, I maintain a timeline of significant historical events
in our field (including some infamous quotations and notable predictions) which it
is hoped will provide a useful resource for students and researchers interested in
learning how the speech technology field has developed over the years.
Whilst there is considerable interest in the possibility of people interacting with
‘intelligent’ agents for a wide range of applications, as yet there is no underpinning
science as to how create such artefacts to ensure that they are capable of providing
an effective and sustainable interaction. This is especially true in the case of
human-robot interaction where the look, sound and behaviour of a robot may not be
consistent - a situation that can trigger feelings of eeriness and repulsion in the
users. I have developed the first mathematical model of this so-called ‘uncanny
valley’ affect (published in Nature), and I am currently investigating the implications
for designing autonomous social agents (such as robots) whose visual, vocal, cognitive
and behavioural ‘affordances’ are appropriate to the role for which they are designed.