Recently research has discovered that sound appears before the contact of the string with the hammer in the piano tone. This sound is called the ``touch precursor'' or ``early noise'' and is observed only in a staccato type of touch [A. Askenfelt, Proc. SMAC 93, 297--301 (1993); G. W. Koornhof and A. J. van der Walt, ibid. 93, 318--324 (1993)]. In this article, analysis of the touch precursor is reported for two cases. The first case analyzed was the piano tone at three different levels (mezzoforte, forte, and fortissimo) played by a mechanical actuator. The touch precursor was observed in each sound. The results show that the lower the touch level becomes, the longer the duration time of the touch precursor becomes. The frequency of the touch precursor is almost constant, but slightly lower in the low-frequency range. The amplitude of the touch precursor gradually increases from the onset until the beginning of the string vibration. The second case analyzed was the piano tone played by a pianist using two different staccato touches, who pressed down the key by a strained finger and a relaxed finger. The results show that the duration time of the touch precursor is slightly different.