Alastair tutors at the University of Edinburgh in subjects relating to the perception and nature of sound (acoustics, psychology of music, and synthesis). He previously taught and researched at the University of York, KTH Royal Institute of Technology Stockholm, and the University of Kent, including the following areas of interest:

Synthesis for musicians

Musicians who want to synthesise or manipulate sounds usually have to learn the techniques and taxonomy of a new and unfamiliar area. Synthesisers, whether analogue or digital, describe sound in terms such as waveforms, envelopes and filters. These descriptions of sound, while often directly relating to the means of sound production, are often non-intuitive and off-putting for musicians. Musicians already have a complex lexicon to describe musical timbre and features, and this project seeks to use some of that language to control synthesis

A prototype synthesiser has been developed which musicians are able to operate intuitively. Research initially studied the words musicians use to describe timbre (such as bright, rich and nasal), and sought to develop relationships between those timbral adjectives and measurable acoustic features of musical stimuli. The results from this were then implemented in a software synthesiser, and testing suggests that non-technical musicians are able to readily understand and manipulate the new synthesiser with a confidence and proficiency previously barred to them.

The synthesis method used is additive synthesis, based on harmonic analysis of sampled instruments, and has been implemented in puredata (pd).

Personnel: Dr Alastair Disley, Professor David Howard (University of York), Dr Andy Hunt (University of York)
Funding: EPSRC grant GR/T06384/01 (3 years)

Comparative performance of compressed audio formats

Considering the ubiquity of compressed audio in modern life, such as MP3 players, digital radio and TV, there is little academic research into its perceived quality by end-users. Competing formats (such as the open source OGG Vorbis or proprietary formats from Apple and Microsoft) are said to be "better" than MP3s, but this is rarely measured in a rigorous way.

This project has applied formal testing methodology to this area, studying listener quality ratings of different audio formats. This has included examination of the effect of different genres and reproduction technologies (headphones, loudspeakers etc.) on the results.

Personnel: Dr Alastair Disley, Daniel Speich (University of Kent), Matthew Duck (University of Kent)
Funding: University of Kent Individual Research Fund

Internet-based listening tests

Traditional listening tests exploring areas of musical cognition and perception interest have been hampered by the necessity to gather enough suitable listeners in one location. Dr Alastair Disley began to use the Internet for listening tests in 1999, and many other researchers have since found its convenience irresistable and irreplaceable. However, much of this work either ignores or makes assumptions about the amount of control that is normally central to conventional offline listening tests. Can such tests be reliably conducted over the Internet?

Initial results were promising, within certain carefully defined parameters.

Personnel: Dr Alastair Disley, Professor David Howard (University of York), Dr Andy Hunt (University of York)
Funding: EPSRC (as part of Synthesis for Musicians, above)

Do expensive instruments sound better?

Musicians can spend many thousands of pounds on good new or second-hand instruments that appear little different to the untrained eye from much cheaper models. An initial foray into this complex and potentially controversial field has revealed that trained musician listeners do rate expensive cornets as sounding better, despite not knowing the price, make or model of the cornet they were listening to.

Personnel: Dr Alastair Disley, Colin Batt (University of Kent)
Funding: University of Kent Individual Research Fund

Pipe organ stop identification

How do listeners identify the musical sounds they are listening to? Within the context of pipe organs, Alastair has studied the ability of trained listeners to make identifications of various recordings from which important sonic features such as transients have been removed. The results show a divergence between those features necessary for classification, and those necessary to give the impression that the sounds are from a real pipe organ rather than a simulation.

Personnel: Dr Alastair Disley, Professor David Howard (University of York)
Funding: STINT grant (Sweden) and University of York (UK) studentship

Technology and musical engagement

Alastair and colleagues from his time at the University of York have explored a number of different ways in which relatively simple technology can be used to engage with people through music. These range from music therapy and music education to less guided interactions, exhibits and installations.

Technologies usually involve some form of sensors or more clearly defined controls, interacting with computers or programmable standalone devices, to generate musical (and often visual) responses to a stimulus. A summary of many of these projects was given at the ASA May 2007 meeting, as although individually the projects are often simple, overall the corpus of work demonstrates how simple engagements can have profound impacts on people's lives and wellbeing.

Personnel: Dr Alastair Disley, Professor David Howard (University of York), Dr Andy Hunt (University of York)
Funding: Various

Listener descriptions of pipe organ ensembles

Pipe organs are complex acoustic synthesisers. They provide a single performer with a wealth of timbral possibilities at different pitches. This research studied the pipe organ as an ensemble, and attempted to quantify the terms listeners and players use to describe the different timbres, by analysing the sounds produced, gathering their descriptions, and looking for commonality between them.

Some timbral adjectives proved to be commonly understood across multiple listeners in this context, but there were linguistic differences, even between British and American English speakers. Some time and frequency domain analyses were found to correlate with the use of certain words.

Personnel:Alastair Disley, Professor David Howard (University of York)
Funding: University of York PhD studentship

Sight versus sound - do pipe organ cases matter?

Pipe organ cases can seem synonymous with their contents, but frequently the organ inside can have changed dramatically since the casework was built. In some schools of organ-building, the case is an integral visual and sonic part of the organ, in others it is merely a device to hide the contents, and in some instances the organ is completely hidden away from the listener - or presented as bare pipes with no case. The perceptual influence of the case on both the tonal style of the sound and its quality as an ensemble is an interesting area to study.

Experiments presenting recordings of pipe organs alongside different pictures suggested that a visually impressive case could improve a listener's opinion of the sound, but where the mis-match between organ case and tonal style became too obvious, listeners commented negatively.

Personnel: Alastair Disley
Funding: University of York PhD studentship

Installation: Projected game

This gallery work explored the boundaries between live and mediated experiences of co-operation and play, involving observers in a compelling but simple interactive game based on Atari's Pong. High-level projection generated an immersive environment in which the real-world players and their computer-generated extensions temporarily became one. The questions raised are not so much about whether the boundaries explored here are perceptible, but whether they matter, or are just convenient discriminators that ignore the increasingly complex relationships humans have developed with immersive or portable technologies.

On a purely technological level, the techniques behind this installation have since begun to find their way into everyday life with novel controllers for the Wii or XBox platforms enabling a sense of immersion, although the projection elements have not yet completed this. More generally, various unconnected commercial products now exist which replicate this interactive floor projection concept, but this is believed to be the earliest successful interactive floor projection installation, and was on a larger scale than most modern examples.

Personnel: Alastair Disley (Original concept, design, programming), other MSc students (Realisation and discussion)
Funding: University of York MSc studentship and Lovebytes Festival grant
Exhibition: Graves Art Gallery, Sheffield, 2000.

MIDI wind controller with continuous pitch

In 2000, Alastair was part of a team of MSc students who developed his idea of a MIDI wind controller with continuous pitch control. In artistic terms, this allows a musician to combine the expressive volume control of a classic wind controller with the continuous pitch capabilities of instruments such as violins.

The prototype developed used a 1PSI pressure sensor to control volume, and a Force Sensing Resistor (FSR) to control pitch. As this was continuous, vibrato was possible via a rocking motion on the FSR. An additional location-independent force output from the FSR could control a further independent expressive parameter, giving the resulting instrument a remarkable range of timbral possibilities and a sophistication equivalent to that of many acoustic instruments.

Funding: University of York MSc studentship