drywallsound-proofing
per this post,
Resilient channel is a thin metal channel that is intelligently designed to
substantially improve the sound insulation of drywall, sheetrock,
plasterboard wallsand ceilings. The channel effectively isolates drywall from the
framing studwork,which results in the weakening of sound waves substantially.
Is the following image the section of a Resilient channel?
The key is the air space at the right side, which cannot be connected to the connect studs. Is my understanding right?
Spend the time to clean the edge of the plaster so it is straight, this will save you time and make those top two inches that will be visible look nice. I personally would use a heaver drywall (5/8) to closer match the original and use thinner shims (they sell a cardboard like shim for drywall). Butt the new drywall up the cleaned up line and make sure to use a drywall tape to interface the old to the new. If you don't, the two will surfaces will form cracks between them.
You say the top two inches are the part that will show, but that will also be the hardest and most critical two inches to get right. Drywall and plaster are two skills where experience makes huge difference in the quality of work. It doesn't hurt to get an estimate from a couple of guys and compare that to the amount of time it will take you (plan on taking three times the amount of time as a pro)
In the sound studios where I work, we've had several rooms added using RC for acoustic dampening. The drywall is hung in the same orientation as the wall studs, but the pattern for screws holding the drywall is done differently to attach to the RC channel. I'll include an image showing the method I am most familiar with:
Best Answer
Yes it is resilient channel, called RC1. The website you linked to has all that information.