What is resonance box?

Answer 1

The exhaust pipes in automobileexhaust systems are designed as acoustic resonators that work with the muffler to reduce noise, by making sound waves "cancel each other out"[1]. The "exhaust note" is an important feature for many vehicle owners, so both the original manufacturers and the after-market suppliers use the resonator to enhance the sound. In 'tuned exhaust' systems designed for performance the resonance of the exhaust pipes is also used to 'pull' the combustion products out of the combustion chamber quicker. (From Wikipedia)

Answer 2

A resonance box is a sound-producing chamber used in Musical Instruments, such as string instruments or percussion instruments, to amplify and enhance the sound produced by the instrument. It is designed to vibrate sympathetically with the vibrations created by the instrument, resulting in a richer and more resonant sound.