A piano turns a small motion from a finger into a rich musical sound that can fill a room. When a key is pressed, a connected system of levers moves a felt-covered hammer toward a tightly stretched string. The vibrating string creates the pitch, while the wooden soundboard makes the sound loud enough to hear clearly.
Understanding this pathway connects music to physics ideas like force, vibration, frequency, and resonance.
Inside a grand piano, each key is part of an action mechanism that controls how energy moves from the player to the strings. The hammer strikes the string and quickly rebounds so the string can vibrate freely. These vibrations pass through a bridge into the soundboard, which pushes much more air than the string alone could.
The open lid and shape of the piano help project the sound waves outward toward listeners.
Key Facts
- A standard piano has 88 keys, usually spanning from A0 at about 27.5 Hz to C8 at about 4186 Hz.
- Higher frequency means higher pitch: pitch increases as frequency increases.
- Wave speed on a string follows v = fλ, where v is wave speed, f is frequency, and λ is wavelength.
- For a stretched string, the fundamental frequency is f = v/(2L), where L is the vibrating string length.
- Increasing string tension raises pitch, while increasing string length or mass per length lowers pitch.
- The soundboard amplifies sound by vibrating with a larger surface area and moving more air than the string alone.
Vocabulary
- Key lever
- A key lever is the long wooden part under a piano key that pivots to transfer the player’s finger force into the action mechanism.
- Hammer
- A hammer is a felt-covered part that strikes a piano string to start its vibration.
- Frequency
- Frequency is the number of vibrations or wave cycles per second, measured in hertz.
- Soundboard
- A soundboard is a thin wooden panel that vibrates with the strings and makes the piano sound louder.
- Resonance
- Resonance is the strong vibration that occurs when an object is driven at or near one of its natural frequencies.
Common Mistakes to Avoid
- Thinking the key itself makes the sound is wrong because the key only starts the action mechanism that causes a hammer to strike a string.
- Assuming louder notes have higher pitch is wrong because loudness depends mainly on vibration amplitude, while pitch depends on frequency.
- Forgetting that the hammer must rebound is wrong because if the hammer stayed on the string, it would damp the vibration and stop the note quickly.
- Saying the soundboard creates the pitch is wrong because the string sets the main frequency, while the soundboard mainly amplifies and radiates the sound.
Practice Questions
- 1 A piano string vibrates at 440 Hz. How many complete vibrations does it make in 3.0 seconds?
- 2 A string has a wave speed of 260 m/s and a vibrating length of 0.65 m. Using f = v/(2L), find its fundamental frequency.
- 3 Two piano notes are played with the same key force, but one sounds much louder when the lid is open. Explain how the soundboard and open lid help project the sound.