The sound files in sound table 4.1 below, illustrate the range of tonal colour of one sound defined by its various directivity.The variation in timbre belongs to the single sound of C2v20, captured by eight microphones as it radiated within the 180° MW sound field. Each row of eight sounds is from the Stuart M19(STU) and Steinway STE pianos.The velocity strike of the key is of the slowest (softest) force , v20.
| C2v20 47s MW | Mic1 180° (3m) | Mic2 60° (3m) | Mic3 90° (3m) | Mic4 120° (3m) | Mic5 150° (3m) | Mic6 180° (3m) | Mic7 hammer strike (10cm) | Mic8 90° (6m) |
| STE USB Audio 4 | 1. C2v20 STE MW mic1.wav | 3. C2v20 STE MW mic2.wav | 5. C2v20 STE MW mic3.wav | 7. C2v20 STE MW mic4.wav | 9. C2v20 STE MW mic5.wav | 11.C2v20 STE MW mic6.wav | 13.C2v20 STE MW mic7.wav | 15.C2v20 STE MW mic8.wav |
| M19 (STU) USB Audio 4 | 2. C2v20 M19 (STU)MW mic1.wav | 4. C2v20 M19 (STU)MW mic2.wav | 6. C2v20 M19 (STU)MW mic3.wav | 8. C2v20 M19 (STU)MW mic4.wav | 10.C2v20 M19 (STU)MW mic5.wav | 12.C2v20 M19 (STU)MW mic6.wav | 14.C2v20 M19 (STU)MW mic7.wav | 16.C2v20 M19 (STU)MW mic8.wav |
| Individual microphone sounds, C2v20 MW Sound table 4.1 USB Audio 4.0 : Trks 1-16 | ||||||||
The collective array sound of the above note, C2v20:
| Stuart C2v20 M19 (STU)MW mxd array .wav |
Steinway C2v20 STE MW mxd array .wav |
| C2 v20 MW Mixed Array Sound table 4.2 | |
The Stuart sound of the note C2 65.406 Hz was found to have a more extensive harmonic and dynamic spectrum across all the partial frequencies. The string scale dimensions and harmonic vibrations in the soundboard correspond to the radiated sound to 3 metres and 6 metres. The dimensions of string density and the soundboard vibrations, combine to form the resonating system of the piano.
The string cannot radiate a sound wave itself, its motion has to be transferred to a much larger object which can serve as a much more efficient radiator of sound. 239
In the bass section of the piano compass, where C2 is situated, the Stuart piano has significantly longer strings of higher yield capacity and lower inharmonicity, set at significantly higher tension. The Stuart soundboard was found to vibrate harmonic frequencies of C2, at 57% higher amplitude than the Steinway soundboard. Of the four notes tested, the sounds of the Stuart piano note C2, at each velocity strike, produced the most extreme tonal comparisons to Steinway.
The volume level of piano sound radiated to each microphone is described as Sound Pressure Level, (SPL). The information for the description of STE and M19(STU) piano tone quality was derived from the recordings conducted in the MW performance space, in a 180° array of 6 microphones at 3metres, mics 1-6, one microphone at 6metres, mic8 , and a close microphone positioned 10cm above the hammer strike of the string, mic7.
239Anders Askenfelt, “Introduction: Basics Of Piano Acoustics: Sound radiation and impedance mismatch” FIve lectures on the Acoustics of The Piano, WWW-edition. https://www.speech.kth.se/music/5_lectures/introd/introd.html (2000). Retrieved 8th April, 2015
