mook johnson wrote:
I've googled this and all the information is aimed at soundPROOFING
the walls. I'd just like to make a decent reduction in the amount of
sound that passes through the walls.

The usual advice is the add another layer of drywall with some
insulation between, put staggered studs so the wall board from one
room does not touch the wall board in the other room, etc etc. All
of these make perfect since and would be very effective at reducing
the sound transmitted but they are major projects.

I'm looking for bang for the buck here.

Right now, I have two bedrooms that share a wall. One has my 1 year
old light sleeper and the other my 3 year old noise maker (toys that
play music and talk). Also both of these bedrooms share a wall with
my living room where the TV is. To make matters worse I have some
hearing damage so I need the TV a little louder than usual so I can
hear what people are saying. Not blasting loud but I can't turn it
down to whisper levels and make out all of the words.

The wall construction is typical with a 2x4 studs between two 1/2"
drywall sheets.

Is there a product that can be blown into the walls through small (say
1-2")holes between the studs, in the top sil (non load bearing sil
from in the attic) or the sheetock itself? I'm thinking of some type
of blow-in insulation to reduce the sound from echoing in the dead
space between the two sheetrock walls.

I've seen several say that when they remodel and put plain old
insulation in there interior walls with nothing else special it made
a notiable difference. I'd like to duplicate that except witout
removing the walls.

Consider the sequence:
* Excessive sound vibrates the sound-side sheetrock
* The sound-side sheetrock transmits this vibration to:
a: The air between the two layers of sheetrock
b: The 2x4 holding up the wall
* Both "a" and "b" transmit the vibrations to the quiet-side sheetrock and
from there to the quiet room.

Filling the cavity between the two rooms may mitigate "a", but not "b".

I suspect MOST of the sound transmission is caused by "b", so filling the
cavity will not be a perfect solution.

The BIGGEST "bang for the buck" is a set of earplugs. Fifty cents.