Singing is an activity that many indulge in and find deeply rewarding for a number of reasons. We are looking at voice development and voice change in girls (Professor Graham Welch, Dr Evangelos Himonides and I are recording girl choristers at Wells Cathedral on a regular 6-monthly basis) are making and boys (Professor Martin Ashley and I) who are and are not cathedral chorister with a view to improving understanding of the nature of the normal and pathological growing human voice.

How a choir tunes the notes of chords is basic to improving the overall sound, blend and listening pleasure for the audience and choir alike. Most important is the relationship between tuning and perceived consonance, which is heightened when the individual notes of chords are tuned in just temperament as opposed to equal temperament. On the face of it, this sounds like something that is easy to measure by tracking the fundamental frequency of the voice. However, there are other aspects that need to be considered that affect our perception of pitch and our work is looking at these. We have worked with a quartet from the auditioned Royal Holloway Chapel Choir.

Speech synthesis is commonplace in many systems where a message needs to be communicated, but the synthetic output although highly intelligible, is rarely if ever mistaken as being from a human source. Understanding better what the acoustic cues in speech are that cue naturalness (as opposed to intelligibility) is the driver for this work, which is looking at the true 3-D shapes of the human vocal tract and how to synthesise speech from them. Work with the University of York (Department of Archeology) and Leeds Museum is looking at a historical vocal tract of an Egyptian Mummy.

This work is an offshoot from the synthesis using 3-D vocal tracts, and it makes use of 3-D prints of vowels that are placed atop loudspeaker drivers driven by a synthetic larynx source waveform whose pitch and amplitude can be varied. The organ can be played via a standard music keyboard or via joysticks. Performance with the organ have included a flash-mob opera after dinner events for the Royal Academy of Engineering, science fairs and public engagement sessions. The reason for this work is to investigate the organ's potential as a new musical instrument, including as a modern Vox Humana pipe organ stop with Harrison and Harrison Organ Builders in Durham (existing Vox Humana stops sound most unlike the human voice!).

The change in muscular control with the onset of Parkinson's disease also manifests itself in speech production and it is possible that this is earlier than limp tremor. We are working with Dr Steve Smith from the University of York (Department of Electronics) to explore the speech of patients with Parkinson's disease to explore whether their speech production with a view to assessing whether or not onset might be detected earlier.

A crucial part of all audio work is understanding better how the human hearing system works, which encompasses psychoacoustics, hearing physiology, neural carriage of information and high-level signal processing. Whilst much of this is impossible to measure directly, listening experiments can provide significant useful information that can be used to improve analysis systems.