A must watch YouTube video on stylus in the groove!!!

That was for Miller..

Word salad to you. And that is your lack of understanding and vision. And dont send me a stupid private message like the one you sent in early March. You draw a blank. Tom

So the expert here in the video is using a digital term to describe motions which are actually shear waves that are cut into the the vinyl.. The stylus tracks those inscribed shear waves and converts that motion into an electrical signal. A speaker also has motion and therefore shear waves created at the launch of the voice coil...all that motion and and shear travels on both side of the cone at the same time as well as thru the material.
A record responds much like a cone in motion..2 sides vibrating one being the dominant surface... the shear waves travel on and thru both. The styus reacts to the shear on both material sides and hears both sides. The stylus also hears a polarity of shear that travels on the surface hits the paper center and is reflected back at the stylus. The same happens when energy is reflected from the lip of the record back at the stylus.
None of this happens at the same time.
The intended signal is being corrupted by the constant shift of polarity which are mechanical waves known as shear waves. A reduction in shear wave interference is what needs to be understood in order to reduce overall distortion. Jitter term is used because some do not know of or understand shear wave motion. Tom

Uberwaltz thats the one I was going to post. Thank you!

All of this was predicted by Zoeppritz in 1907..it has to do with seismic waves that travel thru the Earth...but also thru all materials.
Vinyl and speaker cones of any type. Your audio room, musical instruments of different materials and shapes. 

So if in the the 50 minute video the vibrational energy was to travel the flat plane and intersect a paper label or the outer edge of the record the energy would be reflected back towards the stylus and become a part of the intended signal..it would become a part of the signal. Not in phase..but it would now have many different phase components because of material type and all boundary interfaces..

When an incident P-wave strikes the boundary (or interface) between two media obliquely, the wave is split into reflected and refracted P-wave components and reflected and refracted S-wave components. The reflection and transmission coefficients vary as a function of the angle of incidence (hence, of source-receiver offset) and of the media's elastic properties, which comprise densities and bulk and shear moduli. The Zoeppritz equations (Chapter 1) give the reflection and transmission coefficients for plane waves, as a function of the angle of incidence and as a function of the three independent elastic parameters on each side of the reflecting interface. If the reflection amplitude is observed as a function of the angle of incidence, the variation of that parameter can be used to make inferences about the elastic parameters. Tom

Permalink: https://doi.org/10.1190/1.9781560803201.ch4

I did not write the info preceding the link and posting my name at the end.  Sorry I usually sign off the same way every time. Tom

193,697 male persons in the USA with the name Tom. Tom

Kentucky Tom here. Great Bourbon great Mother Nature and a greater than average  understanding of shear wave transmission in solid materials. Tom