The spectrogram of this sound is graphically illustrated in chapter 4, Spectrogram 4.9, C5v54 MW mic1.The partial frequencies in the Stuart sound of the note C5v54 appear to have decayed at a slower rate than the Steinway sound. The 2nd partial of the Stuart sound has a greater amplitude than the 2nd prt. of the Steinway sound.

It is audibly clear when listening to the comparison of the tones,that the Stuart sound is sustained more than the Steinway particularly at 5s, when the Steinway sound is decaying at a faster rate. The Stuart sound is observed here to be in a comparatively steady state in the after-sound.

Decay

Decay is the rate of decrease in the amplitude or size of the vibration. Decay of a piano string is a compound decay of two distinct transient measures. The onset decay is the initial and a faster decay which occurs within the first second of the sound as a reaction to the hammer strike. When the hammer strikes, the string vibrates in a vertical plane, creating a vertical vibrational force that is transmitted at its maximum amplitude through the bridge of the soundboard. This onset oscillation decays at a rapid rate till the oscillation settles into its elliptical oscillation, usually within the first second of time, which establishes the second considerably slower rate of decay that Gabriel We inreich describes as ‘after-sound.’ ²⁰⁰ Multiple strings vibrating in-phase are characteristic of the onset decay and strings vibrating out-of-phase are associated with the slower after-sound decay. ²⁰¹ The low impedance of the bridge wood is associated with the fast travel of the onset decay, and the high impedance of the soundboard is associated with the slower travel of the after sound decay. ²⁰²

The findings of this enquiry presented in chapter four, establish four distinguishing characteristics of the Stuart sound.Each of these characteristics are found in the onset and after-sound states of oscillation of the piano string vibration.The after-sound is the state of the sound that follows or continues from the initial attack or onset of the sound. Piano sound physicians, Gabriel We inreich²⁰³, A.Benade ²⁰⁴ and Greated & Campbell,²⁰⁵ agree that piano sound is characterised by two distinct rates of decay that coincide with two states of string oscillation. The first oscillation state the onset, is characterised by the initial faster decay of the attack transient, which is a measure of three elements combined, the frequency of the driving force, the frequency of the oscillation and the abrupt disturbance of the hammer strike. The second state of oscillation, the after-sound, has a slower rate of decay and reduced amplitudes of partials.In the after-sound state, the string oscillates in a more settled steady vibration, a steady state.

^{200     7}We inreich. The Coupled Motion Of Piano Strings.
^{201     4}Fletcher& Rossing, 119-124.
^{202     8}We inreich, G. Coupled piano strings. Source: 2J. Meyer,107-108.
^{203     9}We inreich. The Coupled Motion Of Piano Strings.
^{204     2}Benade,165.
^{205     4}Campbell, The Musicians Guide to Acoustics.