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.
The Demonstration: Someone speaks into a microphone that is connected to an oscilloscope and you can see the patterns creates by their voice. Quick Physics: Sound is a wave that caused by vibrations in the air. A pure musical sound, such as a whistle, will produce a sine wave like the one shown above.Someone just talking with produce an irregular wave because it is a combination of sounds and the sounds waves add together to get the composite shown on the oscilloscope.The Details: You can see sound waves when a microphone is connected to an oscilloscope.A microphone changes the sound waves into an electrical signal. The oscilloscope then shows what these electrical waves look like.For a pure sound of only one frequency, like a tuning fork or whistling, the wave looks smooth and regular (as in the picture below). pure musical sound, such as a whistle, will produce a sine wave like the one shown above. Someone just talking with produce an irregular wave because it is a combination of sounds and the sounds waves add together to get the composite shown on the oscilloscope.