Piano tone control through variation of “weight” applied on the keys

To control the tone of their instrument, piano teachers at University of Montreal recommend to act on the double escapement action by modifying the “weight” applied on the keys. When the pianist uses more weight, the key is pressed to the bottom of the keyboard and the pianists feel a bump when they pass the escapement threshold. When using less “weight”, they play more at the surface of the keyboard. The present study aims to verify if this variation of weight has an impact on the piano tone. Two series of recordings were analysed. In a first series, pianists played a short musical phrase varying several control parameters (with/without weight, with/without pedal) and at several intensity levels. In a second series of recordings, isolated notes were played in the same conditions. Simultaneously to the recording of the piano tones, a video image of double escapement grand piano action was captured with a camera placed inside the piano. The analysis of the data shows that the piano tones produced with and without weight differ along several acoustical descriptors (temporal and spectral features). The main parameters which are modified are related to the quality of the attack.