Coconut shell is uniquely robust, lightweight and greatly damped due to micropores and longitudinal fibers. Simply put, it does not generate any side-tones even at the extremely high signal power.
Separately worth noting the great shape, dimension ratio and unique internal cell structure, which is starting to get material engineers' attention. Although there is a wide range of kinds, only 1% can be considered to be suitable. It is only the first of 5 stages of a complex technological process of selecting and processing, providing excellent product quality.
Protected by patents (use of coconut endocarp for acoustics):
UA89355, US10219070, UA204029, US5225404