I go 4 fingers down from the collar on the front, and just under the front collar impression on the backside of the shirt. everyones fingers are different so I measured mine and the 4 fingers measure 3.5. I also use my left hand to guage where to put left chest logos.
Grey noise then, has a sound frequency that, if translated to a light frequency, would roughly be the color grey. Grey noise is a random sound that is distinguishable from other types of sound because it sounds the same, to the human ear, at all frequencies.
1 Having a high pitched hissing sound ringing in the background. 2  Having a high frequency ringing sound in an ear or ears. 3  Having a 'stopped up' feeling and/or 'plugged' sound in one or both ears.  Having an inability to hear certain sounds because the ringing sound is too loud.