Dolphins have a lipoma on their heads. What effect does it have on vocalization?

Dolphins don't have sound belts like other animals, so sounds don't come from their mouths. At present, it is generally believed that the sound source of dolphin echo location is the valve and airbag system in its head. Dolphins suck air into the airbag system. When the air flows through the previously closed valve connected to the airbag, the edge of the valve will vibrate, thus generating sound waves. It seems that when we close our lips and blow from our mouths, our lips will vibrate and make a sound. In front of the valve and airbag, there is a "lipoma" which acts as a "whistle lens" to focus the sound waves generated by the airbag and the valve into a beam and emit them directionally.