Valve release
Exhale monotonously, creating resistance by restricting airflow between the teeth. During this process, the abdominal muscles play a significant role in driving the last portion of exhaled air. The breath-hold serves as an indicator. If exhaling was slow enough, after holding the breath, ‘air hunger’should start rapidly.
The sound produced resemble those made during a gas leak or when depressing the valve stem of a car wheel.