Total damping equals neck friction plus radiated sound, with friction dominant

Evidence

We can sidestep the confusion by invoking the “maximum power dissipation on resonance” principle. On resonance, we ask: what is the choreography of the motion that leads to maximum power delivered to the resonator? … There are two forms of damping: friction of the air with the neck of the vessel, and sound power radiated by the resonator. In real life, friction usually trumps sound radiation. — Eric J. Heller, Why You Hear What You Hear- An…, 1219