NW Mailing List nw-mailing-list at nwhs.org
Sun Nov 26 21:51:39 EST 2006

Well, back in my music days I could make a guitar squeal with what's called a pinch harmonic.
I heard 1218 squeal on a video one time in her excursion era. Its just a high pitch resonance harmonic where whatever is creating the sound vibrates at either 2x or 4x its regular wavelength.
Ben Blevins

NW Mailing List <nw-mailing-list at nwhs.org> wrote:
The Y6's and A's had the same whistle. The higher
pitch in the Link recording was caused by closed pipe
harmonics, or "overblow" which can happen with both
whistles and horns. The PRR/PC/Amtrak Metroliners
were another example of frequent overblow harmonics
changing the basic sound of the horn (two notes in
that case). Whether it's controllable or not, I don't

A less spectacular version of this can be heard on
numerous 1218 recordings during fantrip days where a
certain technique on the whistle cord (probably a
sudden yank) can produce an initial "squeak" from the
whistle before it settles into its more familiar,
lower pitched "hoot".

I don't know enough to give the reason for the
difference in the sound or relative harmonic tones but
it's some sort of interrelationship between
fundamental, first and second harmonics, IIRC. It can
occur in whistles, horns, pipe organs and guitars
(maybe others?). Help anyone??

Dave Stephenson

--- NW Mailing List wrote:

> On one of O Winston Links recordings at Blue Ridge

> (Thunder on the Blue Ridge) , a coal train is

> recorded with the lead engine's whistle breaking

> into a high pitched scream -- the lead engine was

> usually an "A" , did any "A"s have another whistle,

> or was it something the crew did to make the scream

> . or was it the "Y" ?? Ron H



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