Touch upâs should be done minimum 4-6 weeks post the initial treatment. This allows time for eyebrows to heal fully before perfecting them for the second time. Free touch-ups are only valid up to 3 months from initial procedure date.
Re: The Tinny sound? Most folks that are concerned about a tinny noise with aluminum boats are referring to the noise generated by the hull moving through the water (which can be modulated/reduced through many different avenues). You mention vibration and rpms, so I'm guessing that you're not referring to that sound.
This happens in a mouthpiece that's attached to the instrument, causing the air in the instrument to vibrate. Any instrument that produces sound in this way is part of the brass family. There are two ways to change pitch in a brass instrument. The first way is to make the tubing of the instrument shorter or longer.