Anyone who notices my posts knows I'm, at best, an oddball, when it comes to sound. That aside.
The LC Polar Express is, IMO, too loud and more than a tad tinny. I was going to replace the 8ohm, with a 16 ohm speaker. As folks here mentioned, that will lower the volume. My wife said "put some tape over the speaker." It's worked for any number ofannoying kids toys. Someone here may have also suggested it.
I took 2 squares of rough finish construction paper (the stuff kids draw on) and put them between the speaker and the chassis. 1 sheet helped. 2 were better. The sound is decreased and it doesn't have that grating (to me) edge. I don't have recording, but if the sound grates on you, try it.