dB of the partials make up the volume of the composite dB level of the note, the composite note volume, or sound pressure level, (SPL). Importantly for piano sound, the waterfall spectrogram also plots time, in milli seconds (ms), to illustrate the exponential decay of the amplitude of each partial frequency, over the time period of the sound’s duration.

The stiffness, the set tension and the stretched expansion of the coupled piano wire (string) creates periodic changes in the strings length, when excited by the force of the hammer, and produces in harmonicity.This causes the partial tones to vibrate at exponentially sharper frequencies than the multiples of the fundamental frequency. As the strings are shortened and set at progressively higher tensions, as the pitch rises, the ratios of in harmonicity increase.

The following sounds recorded in the MW space, exhibited a slower rate of decay in the fundamental frequency of the M19 (STU) Stuart piano, and produced a sound with distinctly higher levels of sustain than the Steinway D (Olley)concert piano, STE No 574500.

C5v54 MW mic1

Soundboard Vibrations : The Steinway soundboard resonated a larger fundamental, and larger 4th& 5th partials than Stuart, ,and the Stuart s-board vibrated with a larger 2nd partial frequency. Both these findings correspond with the peak dB comparisons of the fundamental and 2nd partial, illustrated in the spectrogram. Overall, the Steinway soundboard vibrated in amplitudes 46% larger than Stuart for C5v54.

Instrument Volume Mic 7: STU 90 dB, STE 89 dB

String Scale: For the note C5, the diameter of the Paulello-Stuart wire is .35mm thicker, the tensile strength of the Paulello/Stuart wire is 138 N/mm² higher. The Paulello-Stuart wire for C5 is 4.5mm longer, and is set at 7kg higher tension. The yield or capacity of the Paulello-Stuart wire is approximately 10% higher than the Roslau-Steinway wire.

C4v54 MW mic2

Soundboard Vibrations:

The Stuart soundboard resonated larger amplitudes of the fundamental and 2nd partial frequencies. Overall, the Stuart soundboard vibrated at 71% greater magnitude than the Steinway soundboard for C4v54

Instrument Volume Mic 7: STU 89 dB, STE 86 dB