1.  
2.  
3. A wider harmonic spectrum in the onset state of the sound,
4. A more comprehensive projection of sound to 6 metres.

Detailed descriptions of the four characteristics are presented and illustrated in chapter four, Qualities of the Stuart Piano Sound. The terminology, processes and methods used to identify the characteristics are discussed in this chapter.

Comparative data sets of Stuart and Steinway sounds were compiled and analysed to test Wayne Stuart’s claim that the Stuart sound has a greater clarity, sustain, and an expanded dynamic range. ¹⁷⁰
The evaluations of piano tone began by examining each sound in two entities, partial tones and composite tones.

Partial Tones

Partial tones are also described as partial frequencies, simple tones, pure tones, partials, upper partials, sinusoidal, egen frequenices, harmonics, overtones and modes of vibration.¹⁷¹ These tones are of a single frequency, not of strong individual audible sound, they combine to make up the harmonic structure and subsequent tonal colour of the composite tone, heard as the piano note sound. They are numbered as Fundamental, 2nd partial, 3rd partial , 4th partial…etc. Sounds that are different in tonal colour are found to have different amplitudes of partial tones.

Tone quality, or timbre, is indicated by the spectrum of simple tones, harmonics or overtones, contained within one complex musical tone. Timbre [also] depends strongly on envelope: on how the sound varies over time.¹⁷²

The fundamental’s frequency determines the frequency of the complex tone. For this reason partial frequencies are proportionally related to their fundamental frequency.

………. for the largest portion of the piano sounds, the fundamentals of the partial spectra dominate. Only in the two lowest octaves of the tonal range, the intensity maximum is shifted to overtones in the frequency range of about 100–250 Hz.¹⁷³

The relative proportion with which each overtone intervenes in the resulting vibration determines to a great extent the particular character, quality or timbre of the generated tone. The pitch of the string’s complex tone is determined by the fundamental frequency.¹⁷⁴

Aside from the fact that tone color naturally changes over the tonal range of an instrument, as determined by the location of the fundamental, it can be said in general, that a tonal impression is brighter, and possibly

¹⁷⁰ See Wayne Stuart’s claims : pages 17 & 51.
¹⁷¹Murray Campbell, Greated, C. The Musicians Guide to Acoustics, (New York:Schirmer,1987),142.
¹⁷² Joe Wolfe, “Timbre and envelope,” Pyshclips. School of Physics – UNSW,10 April 2015, http://www.animations.physics.unsw.edu.au/jw/timbre-envelope.htm.
^{173     2}Meyer,116.
¹⁷⁵² Roederer,118.