Is sound is necessary for biotic life?
Sound is not a requirement for life.
However, living things use sound in various ways.
The most obvious use of sound by living things is via communication. Some animals use mating calls to find a partner. Other calls warn members of a group of animals that danger is nearby.
Echolocation is when living organisms use sound to determine the location of an object. The animal emits a call. The location of an object is determined by the amount of time that it takes for the sound wave to be reflected back to them. This may be done in order to steer clear of predators or locate prey. Other organisms use echolocation when navigating through dark passages (such as caves) so they don't run into obstacles. Dolphins and bats are two examples of animals that use echolocation.
Thus, sound is not needed to live. However, it helps some organisms find food and stay protected so that they may live longer.