One thing I learned from Tai Chi is that when you do something, your whole body should do it, naturally. I haven't seen my Qigong video yet, so I don't know exactly what Master Lin looks like doing his breathing. But he may be breathing with his entire body, with his vocal chords and shoulders complimenting the breath, instead of going against it.
I've seen a Tai Chi master with a booming voice, and an Aikido instructor whose voice would naturally contort while excercising his Chi. It's like my teacher used to tell me, "A dog can bark all day, but he never loses his voice."
