Analysis of the Part-Pedaling Effect in the Piano

Analysis of the Part-Pedaling Effect in the Piano
Heidi-Maria Lehtonen (1), Anders Askenfelt (2), and Vesa Välimäki (1)
(1) Dept. of Signal Processing and Acoustics, Helsinki University of Technology, TKK, Espoo, Finland
(2) Dept. of Speech, Music and Hearing, Royal Institute of Technology, KTH, Stockholm, Sweden
This letter reports basic acoustic phenomena related to part-pedaling in the piano. With part-pedaling, the piano tone can be divided into three distinct time intervals: initial free vibration, damper-string interaction, and final free vibration. Varying the distance of the damper from the string, the acoustic signal and the damper acceleration were measured for several piano tones. During the damper-string interaction, the piano tone decay is rapid and the timbre of the tone is affected by the nonlinear amplitude limitation of the string motion. During the final free decay, the string continues to vibrate freely with a lower decay rate.
The manuscript is published in the Journal of the Acoustical Society of America Express Letters in August 2009 (vol. 126 no. 2, pp. EL49-EL54).
Sound samples
    Sound examples related to Fig. 1: Sounds without the sustain pedal, with part-pedaling and with full sustain pedal

    In the following, the recorded sounds C1 (f0 = 32.70 Hz), A1 (f0 = 55.24 Hz), G2 (f0 = 98.12 Hz), G3 (f0 = 196.4 Hz), D4 (f0 = 294.6 Hz), and A4 (f0 = 441.7 Hz) are played without the sustain pedal, with part-pedaling, and with full sustain pedal:

    [ (1) no sustain pedal --- (2) part-pedaling --- (3) full sustain pedal ]

  • C1
  • A1
  • G2
  • G3
  • D4
  • A4

  • Sound example related to Fig. 4: Nonlinear effects of the damper-string interaction

    In the following, the effect of the damper-string interaction is presented through an example tone C1 that is related to Fig. 4 in the manuscript. The nonlinear effect caused by amplitude limitation is most prominent in bass tones. In the example tone, first the part-pedaling tone is played followed by the tone played with full pedal. The example is the same as above except the tone without the sustain pedal is excluded to make it easier to concentrate on the difference between the part-pedaling and full pedal tones.

    [ (1) tone with part-pedaling --- (2) tone with full pedal ]

  • C1

  • In the following, 0.5 s excerpts from the six example tones are presented. The purpose is to illustrate the differences between the tones played with part-pedaling and with full sustain pedal in terms of brigthness during the final free decay. In the case of tones played with full sustain pedal, the starting point has been determined by searching the time interval where the energy of the signal matches the energy of the tone played with half-pedaling. First the original tones with half-pedaling and full sustain pedal are played, and after that are played the excerpts.

    --> pedaling/
Author: Heidi-Maria Lehtonen
Modified: November 15, 2010 by Heidi-Maria Lehtonen