Passenger Trains > What type of horn does MARC have?

Been watching the Railstream live wqebcam in Shenandoah
Junction, West Virginia (where the NS crosses over the CSX,
about 70 miles W of Washington, D,.C., by rail) and heard
MARC horns for the first time. Those horns sound really
odd, and are not pleasant at all to listen to, but they are
not at all overly loud, and they are impossible to ignore,
so they do the job of alerting nearby pedestrians and motorists
very well.

Which leads me to this post. I have never heard any RR horns
that sounded anything like these MARC horns.

So, I would like to know the following:
Manufacturer
Model
Number of bells
Musical notes sounded
Date these were first made

You-hoo, Ed K! Hope you know the answers!

TIA!!

I assumed the usual K5LA, but perhaps not. It is Amtrak's P42 horns that are more often than not out of tune.

joemvcnj ---
Nope - most definitely not a K5LA. I have never
before heard horns that sound like MARC horns --
raucous and very dissonant, like all horns are
a minor second apart in pitch (musician talk
for the difference in pitch between a white key
on a piano and the black key next to it).

The horns that are so odd are on the locomotives,
as the ones on their cab cars are rather different
in sound.

I was really hoping Ed K. would see this and reply,
as he should know the answer. I posted this here
instead of just PMing Ed, because I thought others
might also be interested in the answer.