Tuning forks are sometimes placed inside of hammers to amplify the sound they produce. This is done by attaching the tuning forks to a wooden sound box, which helps to amplify the sound since tuning forks are notoriously difficult to hear without amplification . The sound box acts as a resonator, enhancing the vibrations and thus the sound produced by the tuning forks.
When tuning forks is struck, it vibrates at a specific frequency, producing a sound wave. The sound wave is a mechanical wave that propagates through the air by causing the air particles to vibrate. The amplitude of the sound wave, which determines the loudness of the sound, depends on the amplitude of the vibrations of the tines .
In some cases, a microphone/preamp/scope setup may be used to visually demonstrate the pure sinusoidal sound wave produced by the tuning forks . This can help in situations where the tuning fork's sound needs to be heard by a large group or where the sound needs to be analyzed for its frequency components.
It's also worth noting that the directivity patterns of tuning forks change with distance. At close distances, the sound field exhibits distinct differences in directivity patterns and vector intensity maps due to the quadrupole nature of the sound source . This means that the sound can be louder when the tines are aligned in certain directions, which is another factor to consider when trying to make tuning forks louder.
In summary, placing tuning forks inside a hammer or a resonator can help amplify its sound, making it more audible and useful in various applications, from musical performances to scientific demonstrations and sound therapy .