Pitch-scale modifications of polyphonic music are usually performed by manipulating the time-frequency representation of the input signal. Most approaches proposed in the past are thereby based on the Fourier transform although its linear frequency bin spacing is known to be inadequate to some degree for analysing and processing music signals. Recently invertible constant-Q transforms (CQT) featuring high Q-factors have been proposed exhibiting a more suitable geometrical bin spacing. In this paper a frequency domain pitch-shifting approach based on the CQT is proposed. The CQT is specifically attractive for pitch-shifting because it can be implemented by frequency translation (shifting partials along the frequency axis) as opposed to spectral stretching in the Fourier transform domain. Furthermore, the high time resolution of CQT at high frequencies improves transient preservation. Audio examples are provided to illustrate the results achieved with the proposed method.

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This paper presents research into scanned synthesis on a multitouch screen device. This synthesis technique involves scanning a wavetable that is dynamically evolving in the manner of a massspring network. It is argued that scanned synthesis can provide a good solution to some of the issues in digital musical instrument design, and is particularly well suited to multi-touch screens. In this implementation, vibrating mass-spring networks with a variety of configurations can be created. These can be manipulated by touching, dragging and altering the orientation of the tablet. Arbitrary scanning paths can be drawn onto the structure. Several extensions to the original scanned synthesis technique are proposed, most important of which for multi-touch implementations is the freedom of the masses to move in two dimensions. An analysis of the scanned output in the case of a 1D ideal string model is given, and scanned synthesis is also discussed as being a generalisation of a number of other synthesis methods.

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