How does the impact of a piano hammer affect the sound of a piano note?

In the context of musical sound, the impact of a piano hammer is fundamental to how a note is produced and its resulting timbre. When a player presses a key, it accelerates a felt-covered hammer toward the string; upon contact, the hammer initiates vibration and then must rebound instantaneously to avoid dampening the sound.12

The physical characteristics of the hammer significantly influence the tone:

• Emphasis on Fundamental Pitch: Unlike a sharp point (such as a plectrum) which emphasizes higher overtones to create a "bright" quality, the soft pad of a felt hammer emphasizes the fundamental pitch.3
• Voicing: Because the relative hardness of the hammer is critical to the instrument's sound, technicians perform a process called "voicing." This involves pricking the felt with needles to adjust the timbre and ensure a unified quality across the piano's range.3
• Mechanical Control: The hammer must fly freely toward the strings to allow for dynamic control. If the mechanism is not properly adjusted, the hammer may bounce against the strings, resulting in a stuttering sound rather than a clear note.2