Stuart Tonal Colour Outcomes: relating to Stuart Design Concepts

• The faster rate of decay in the onset of the Stuart string vibration was found to occur because of less resistance to the vertical plane of the hammer strike, due to its vertical coupling.

• The larger amplitudes of the Stuart Fnd. 2nd and 3rd partials, subsequently causes a faster inverse decay reaction in the onset of the sound, as well as a wider harmonic spectrum.

• The Stuart’s earlier change into the slower decay rate (after-sound) is due to a proportionally smaller change in the vibrational mode from vertical to elliptical, i.e. less damping, which is heard in the stability of the tonal balance of the after-sound.

Changes in [vibration] mode = damping. No change [in vibrational mode] can contribute to a greater motion and quicker loss as your figures indicate but the lack of subsequent changes in mode ultimately reduces the overall [energy] loss in comparison to the ever changing back and forth motions of the pinned bridge scenario.²⁵⁰

• The Steinway’s higher degree of stress on the horizontally pinned string which when forced into the vertical plane by the hammer strike, causes a higher amount of damping, resulting in a longer inverse decay rate at the onset, of smaller gradations , subsequently losing more energy over a longer period, before settling into its after-sound.

The comparison tests in tonal colour, conducted in chapter 4 have produced sufficient evidence which supports the claim that the Stuart piano produces a sound that is in distinct contrast to the standardised sound of the modern piano. It has been clear to many listeners that the Stuart sound was audibly different, the data presented in chapter 4 now illustrates the difference we are hearing.

The detailed examinations of the characteristics of loudness, pitch and timbre of the four notes in an identical acoustic environment, excited by an identical calibrated energy source, enabled the tonal differences of the four notes of both pianos to be described in purely technical terms. The transient components of piano sound, attack, sustain and decay have been measured in terms of their magnitude. Temporal measurements of both the composite complex sound, and its individual pure – simple sinusoidal tones or partials were also examined in a detailed investigation of tonal colour. The audio of each sound accompanied each tonal description, serving as a definite audible reference.

In order to achieve clear definitions of distinct tonal characteristic, the examinations conducted in chapter four were limited to the same four single notes, excited by the same mechanically measured velocities, with no damping of the sympathetically vibrating characteristics of the instruments. The pianos were positioned in precisely the same positions within the 180° sound field of 8 microphones. The microphones were positioned at 3 & 6 metres, identically for each piano.

²⁵⁰Wayne Stuart, email interview with author, 22nd June,2015.