Test 4. The duration of the vertical oscillation from the onset, to the beginning of the
predominantly horizontal oscillation. With no horizontal oscillation.
Result: The vertical oscillation of the Stuart/Paulello string extended for 400ms longer than the Steinway/Roslau oscillation, before the occurrence of the predominantly horizontal oscillation ensued. The horizontal vibration began earlier in the Steinway string oscillations.

Summary of the String Vibration tests

The Stuart string has a greater tendency to oscillate vertically, and a lesser tendency to oscillate horizontally compared to the Steinway string. Its oscillations resolve into a narrow elliptical pattern, where the Steinway string resolves into a much wider elliptical pattern. Furthermore the Steinway string begins horizontal motion much sooner in the cycle than the Stuart string. ¹⁶⁵

Peter Phillip’s tests findings confirmed that the Stuart and Steinway bridge coupling each influenced distinctive string vibrations. In the initial stages of the oscillation, the onset period immediately after the hammer strikes the string, the Stuart-Paulello string was found to vibrate for a longer period in the vertical plane and with larger amplitudes than the Steinway-Roslau string.The Steinway-Roslau string was found to establish its elliptical vibration sooner than the Stuart string. In the after-sound oscillation period following the onset , the Stuart string did not oscillate in the horizontal elliptical direction as broadly as the Steinway string. Peter Phillip’s findings support the visual illustration of the slow motion video, where the Stuart string appears to maintain a tighter, more consistent vibration than the Steinway. The fourth test found that the Stuart-Paulello string produced a predominantly vertical oscillation for 400ms longer duration than the Stein way-Roslau string.

The research has found that the string vibration of the Stuart piano sound is significantly different to the modern piano. The overall research objective of understanding the tonal characteristics of the Stuart & Sons piano sound has been well served by these preliminary conclusions about the influenced of the Stuart bridge agraffe has on the oscillation of the string. In response to Wayne Stuart’s comments about the string vibration tests above¹⁶⁶ , the characteristics of the attack, sustain and decay transients within the Stuart piano sound will be investigated in the following chapters 3 & 4, with the expectation to visually and aurally illustrate the effects of the longer more pronounced vertical vibration and reduced damping of the Stuart piano string vibration, with an audibly more stable inner tonal balance.

¹⁶⁵Vibration Test – see Appendix 2.Peter Phillips details and procedures of the above tests are illustrated in Appendix 2
¹⁶⁶Appendix 2.- Wayne Stuart’s comments on the String Vibration tests.