Resonance:
Resonance occurs when the natural frequency of an object matches the frequency of an applied force. In the case of a tuning fork, the tines vibrate at a specific frequency when struck. When the vibrating tuning fork is held in contact with a sounding board, the board also starts to vibrate at the same frequency. This is because the vibrations from the tuning fork are transmitted to the sounding board through the point of contact.
Amplification Mechanism:
The sounding board is typically made of a thin, flexible material such as wood or metal. When the tuning fork's vibrations cause the sounding board to vibrate, the board's larger surface area amplifies the sound waves produced by the tuning fork. The sounding board acts as a resonator, enhancing the sound and making it louder.
Acoustic Properties:
The acoustic properties of the sounding board play a crucial role in amplifying the sound. The board's shape, material, and thickness determine its resonant frequency and how efficiently it can amplify sound waves. Typically, sounding boards are designed to have a resonant frequency close to that of the tuning fork to achieve maximum amplification.
Radiation of Sound Waves:
As the sounding board vibrates, it radiates sound waves more efficiently than the tuning fork alone. The larger surface area of the board allows for greater displacement of air, resulting in louder sound waves. The sounding board effectively couples the vibrations of the tuning fork to the surrounding air, amplifying the sound and allowing it to be heard over a larger distance.
In summary, when a vibrating tuning fork is held in contact with a sounding board, the board's resonance amplifies the sound waves produced by the tuning fork. The larger surface area and acoustic properties of the sounding board enhance the vibrations and radiate sound waves more efficiently, resulting in amplified and louder sound.