I agree, it is sad how carousels these days have turned off the band
organs -- the "voice" of the carousel, and of the [amusement] park.
I have heard complaints on both the type of music and the volume,
mostly from the (usually young) operators.

A plastic barrier seriously detracts from the carousel experience.
Turning off the trumpets is not desirable, as that results in the
loss of the counter-melody portion of the music.

In my work in voicing and tuning band organs for use in closed
spaces, I have found three approaches which are effective in mitigating
organ volume issues, while retaining the quality of the music:

(1) Tune the organ.  Proper voicing, volume, and function reduce
the perceived volume.  Many organs, including those on carousels,
sound substandard due to out-of-tune or improperly voiced pipes.
This issue is often profoundly manifest in the trumpets or other
reed pipes.  The reaction of most of us in this case is "Turn it off,
it's too loud," or whatever.

(2) Regulate (voice) for balanced volume.  High-pitched pipes have
a higher apparent volume than do low notes.  An organ in a closed
space will sound better if the volume of the higher pitch pipes is
controlled and perfected so as to be consistent and harmonious with
the balance of the organ.

(3) Reduce the pressure.  In an effort to control volume, I have
reduced the operating wind pressure on various organs, with very good
results.  The amount of pressure reduction an organ will tolerate
varies with different organs, does require some pipe work for success,
and does sacrifice a little bass, but, done properly, results in a
wonderful sounding organ, with reduced overall volume.

Alan Erb
http://www.mechanicalmusicbox.com/