You are correct up to a point...  stereo sound was available sometime
between 1920 and 1933...  depending on which engineer's memoirs you read.
The first patent wasn't the first stereo or the first usable stereo.  The
stereo that was introduced commercially in late 1958 and early 1959 came
from the later inventions of Harvey Fletcher.  I am talking about modern
commercially recorded stereo.  We were talking about actual recorded stereo
and where recordings might be.  I maintain that pre-1954 was too early
because the reproduction techniques were only possible with engineers on
hand.

Actually stereo sound was accomplished in the laboratory in the early 20's
but only as an experiment, and not patented.  The first US demonstration
was conducted by Harvey Fletcher, then an engineer at Bell Labs, with
Leopold Stokowski in Constitution Hall April 27, 1933.  The orchestra was
in philadelphia and the loud speakers were in Washington, DC's Constitution
Hall.  AT&T claims the credit because the transmitted the telephone wires
to Washington from separate microphones.  The sound was then amplified and
sent into the speakers in the auditorium.  The was the first public
demonstration in stereo outside a laboratory.

It is hard to find the real "first" as AT&T was doing work on stereo in
1920...  the problems were in the consistency, sound levels, frequency
range.  Frequency response was limited and too uneven for anything
approaching commercial reproduction.  Something that would work one time,
did not work the next.

You see, the phonographs of those early times were not electric so there
was no way to connect the recording equipment to the telephone...  Live
stereo was possible, but not recorded stereo with an acceptable frequency
range.  And nothing that could be consistently reproduced.

After Joseph Maxfield of Western Electric invented electrical recording,
we had the Jazz Singer in 1927.  The sound was pretty bad even in mono.
Arthur Keller invented the first stereo stylus in the 30's.  It moved up
and down as well as side to side.  This provided greater dynamic range and
less noise.  But his stereo required to styli.

These first experiments with Stokowski 1931-1933 with live orchestras
produced the first stereo recordings but using two styluses in parallel
grooves on a single platter.  This could not be set up by an individual
and did not provide a marketable product.

All this early research was stopped because of the war and related
electronic research issues.

I interviewed Harvey Fletcher in Provo, Utah before he died.  His work
along with that of his sons led to the modern stylus and the recording and
production techniques on a single master.  One of his sons, James Chipman
Fletcher, became president of the University of Utah and Director of NASA.
I interviewed him again in 1963 about their early work.

Until the Fletcher's completed their work, the stereo recording simply
was not commercially possible with enough sound quality to be reproduced.

Ray Bayles