If this fails, then the Valsalva maneuver may be used. This maneuver, when used as a tool to equalize middle ear pressure, carries with it the risk of auditory damage from over pressurization of the middle ear. The Valsalva maneuver generates about 20–40 mm of Hg pressure. It is safer, if time permits, to attempt to open the Eustachian tubes by swallowing a few times, or yawning, or by using the Valsalva technique of breathing a very small amount of air gently into nostrils held closed by the fingers as soon as mild pressure is felt, before it increases to the point that its release would be painful. The effectiveness of the "yawning" method can be improved with practice; some people are able to achieve release or opening by moving their jaw forward or forward and down, rather than straight down as in a classical yawn, and some can do so without moving their jaw at all by activating the tensor tympani muscle, which is heard by the individual as a deep, rumbling sound. Opening can often be clearly heard by the practitioner, thus providing feedback that the maneuver was successful.