Dinosaurs possessed a highly efficient bird-like breathing system involving large Numbers of air sacs permeating their body cavity and bones.

By varying the groove spacing, the diameter of the single or double diameter hole, and the rear air cavity depth and content, one can obtain absorption over a wide variety of frequencies.

This time, inhale about 70% and hold the air in your upper cavity, but this time, try to relax your shoulders and keep your diaphragm taught.