Daily Diaphone?

[Robert Gift]

Just learned that Lewsitown, Pennyslvania still operates their curfew horn
at 10 p.m.

I used to hear it in the late 50's early 60's when visiting my grandmother.

What I remember was a strange: BEEEEEEEEEP....arrUUgah, BEEEEEEEEEP....arrUUgah, ..... arruugah.
Was last arrUUgah an echo?
Now I believe the "arruugah" was residual pressure leaking off.

[SirenMadness]

It could be an echo, as the buildings around it change the acoustics of the initial blast once it reaches a distance.

[Robert Gift]

The "arrUUgah" sound was so different from the initial BEEEEEEEE that
it must have been residual air.
I assume it was a defect.
But a fascinating defect.

I will try to find someone who lives within earshot and call them at 10 p.m. EST.

I'd love to hear it again after 40 years.
But I fear they will have fixed the "arUUgah" sound.

[SirenEnthusiast360]

What you're describing sounds to me like one of those submarine dive alarms. (the arrrugah part)