A stone wall the size you mention won't help much if at all. You need
to offer a more detailed description, ie. distances, sound source, and
intensity. More often there is no solution for noisy neighbors in
close proximity short of moving or murder. Of the two I strongly
recommend moving. My daughter encountered a noisy neighbor problem
recently with new neighbors (loud music) after much retaliation back
and forth I suggested she move and finally she did to a house I
located nearby on 11 acres. Living in close proximity to neighbors on
small suburban properties will eventually result in feuding over noise
or some issue(s). Even on large acreage one still needs to tolerate
the sounds of lawn mowing, chain sawing, and party music, but it's
typically occasional. Noise is not so bad as noxious odors from live
stock or dying septic systems. So long as one lives near people there
will be noises. Even on ones own isle way out at sea one will still
need to tolerate the constant sqwarking of sea birds. Learn to live
with noises, for eventually in the ground you will have quiet for
eternity. To be honest I strongly suggest ear plugs. Even on 11
acres my daughter still complains about noise from nedighbors although
they are many hundreds of feet apart. I live on 16 acres but I still
can hear lawn mowing and such, but I'm not bothered as I mow too. I
have central air conditioning so I never open windows, my house stays
cleaner and is quiet. Rather than ear plugs I suggest adding
insulation, I did that to save on energy bills and as an unintended
plus my house is very quiet.