Re: [Harp-L] Re: Reed Stress and Temperature

You can easily verify that amplitude goes down when you bend a note.

Take a diatonic reedplate and hold it vertically with the reeds facing away from you while looking in a mirror.

Bring one of the longest reeds up to your mouth and inhale. Note the amplitude (easy to see with the naked eye). Now bend the pitch down. You'll notice two things:

- The amplitude (width of reed swing) gets smaller (narrower travel) as you pull pitch down.
- The reed is pulled closer to the reedplate with lowered pitch.

Now exhale instead, The pitch will come in nearly a semitone higher than the previous unbent pitch, Bend the note up and note two things:

- Amplitude decreases as the pitch rises.
- As pitch rises, the reed pushes away from the reedplate.
Winslow Yerxa
President, SPAH, the Society for the Preservation and Advancement of the Harmonica
Producer, the Harmonica Collective
Author, Harmonica For Dummies, ISBN 978-0-470-33729-5
            Harmonica Basics For Dummies, ASIN B005KIYPFS
            Blues Harmonica For Dummies, ISBN 978-1-1182-5269-7
Resident Expert,
Instructor, Jazzschool Community Music School


>> I doubt but cannot refute your claim that bending stresses reeds more than normal playing.  If it does however, it is because the amplitude of one of the reeds is greater than normal. I posit that reed stress is a function of vibrational amplitude only. Other conditions affect reed stress only to the extent that they affect amplitude.  It seems reasonable to me that a reed will vibrate at a higher amplitude at its natural frequency than when bent to another frequency.
>> Vern

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