This study found that in many sounds, there appeared to be other transitional states of decay between the onset attack and the steady settled after-sound, which defined significant differences in the Stuart and Steinway rates of decay. This state has been named, ‘after-sound unsettled’, as it occurs after the onset attack, though shows a higher rate of decay than its steady oscillation which follows.So three transitional states of oscillation and rates of decay are identified throughout the findings in chapter 4:
i) Initial Onset; ii) After-sound unsettled; iii) After-sound settled. The three states of oscillation are indicated by three rates of decay illustrated in the decay curve 3.2 below.

The volume of the Steinway in this sound is 3 dB louder than the Stuart sound. Often the partial frequencies with larger amplitudes in the onset state will decay faster in that period, as the Steinway does here. The Stuart sound arrives at its settled after-sound oscillation (iii) earlier than Steinway (iii).

Other terminologies used to describe these rates of decay are, ‘Initial Transient’ and ‘Steady Oscillation’ ²⁰⁶ and dual decay rates- ‘Initial rapid, and decreased’ ²⁰⁷ and ‘prompt’ and ‘after-sound.’ ²⁰⁸

Damped Oscillation

The vibrating piano string oscillates in damped oscillation. ²⁰⁹ How the piano is designed establishes the elements of damping. String coupling and the impedance ratios of the strings to soundboard are elements of damping which restrict or control the amplitude and tonal colour of the periodic vibrations over time. Almost immediately after the initial disturbance or excitation of the hammer strike, within .5s, the maximum oscillation amplitude is reached.Subsequently a rapid decrease in amplitude follows, which is associated with the impetus of the vibrating string and soundboard to return back to their rest positions. The rates of decay of each partial tone in both the wood of the bridge, the soundboard and the steel wire of the piano string collectively influences the tonal colour of piano sound. ²¹⁰

^{206     8}We inreich.,
^{207     5}Campbell& Greated.
^{208     9}We inreich.
^{209     7}Roederer,79.
^{210     8}Roederer, 118.