Introduction.

The characteristics of tone colour found in the sounds of the Stuart & Sons piano No 19 in the Music Workshop performance venue are identified, examined and defined in this chapter. The tonal descriptions of the Stuart piano sound were realised by comparing its sound with the sound of the Hamburg Steinway concert D piano, No574500, in the controlled acoustic environment of an eight microphone array set in a curve of 180°, 3meters and 6 metres from the same measuring point of each piano.

The descriptions of tone colour are based on the understanding that the tonal colour or timbre, is determined by how proportions of the partial frequencies intervene within the whole tonal composite vibration of the sound,²³³ at specific time periods of the sound’s duration.²³⁴ Piano sound is in a state of transient decay, therefore the measured state of the sound at a given durational plot over the time period of the note’s sound duration, provides significant information that contributes to understanding the overall characteristics of the tonal colour of the sound. Piano sounds in the lower registers with long wound steel wire strings can sound for 60 seconds duration, whilst shorter durations occur for the higher tones of shorter thinner steel wire strings. Tonal colour therefore needs to be described in terms of the manner in which the transient qualities change over the time of the sound’s duration. The individual partial frequencies and the composite collective of partial frequencies are described in terms of their volume SPL²³⁵ dB, amplitude, and the rate or speed at which they decay, as both dimensions influence tonal colour.

The sounds of both the Steinway and Stuart pianos were activated by a calibrated electronic key striker, which eliminated the variable of ‘human’ pianistic touch. Leaving pianistic expression out of this examination of tone colour, narrows the enquiry to one of tone production of the actual instruments and how their sounds interact within the acoustic of the specific performance hall.

A reference point of standard traditional piano tone was provided by the sound created by the Hamburg Steinway concert D piano, in the same acoustic space. The recorded samples were all created on the same recording date with each piano in identical positions in the space, using the same data microphone positions, as discussed in chapter three, ‘Vibrations and Tone’. The aim of creating the descriptions of the Stuart piano tone, is to establish knowledge on how and why the Stuart sound is different to that of the traditional modern piano, in this case the Steinway D. Realising these tonal characteristics informs musical choices for composition and performance.

^{233     7}Roederer,118.
^{234     4} Wolfe, Pyshclips. University of NSW, School of Physics.Retrieved 10 April 2015
²³⁵ Sound Pressure Level