Re: [Harp-L] More info about combs

["Rick Dempster" <rick.dempster@xxxxxxxxxxx>]

" I think you are right.  The difference is leakage, not materials."
  Vern
With you on that Vern.
RD

>>> "Vern Smith" <jevern@xxxxxxx> 18/09/2008 13:56 >>>

  ----- Original Message ----- 
  From: Philharpn@xxxxxxx 
  To: jevern@xxxxxxx ; jofjltn4@xxxxxxxxxxx ; harp-l@xxxxxxxxxx 
  Sent: Wednesday, September 17, 2008 6:12 PM
  Subject: Re: [Harp-L] More info about combs


  Has anyone got a thumbnail summary of both tests? I recall the SPAH discussion -- but not how the tests were conducted.

  Did the same player play several different harps and ask the audience to identify which was which?
  Yes,  there were four comparisons A - D

  The harps were all Big River in C.  There were combs of doussie, balsa wood, titanium, clear acrylic, black plastic, aluminum, closed-cell foamed plastic, open celled foamed plastic, lead, and concrete.

  The listeners were given forms on which to mark their identifications.
  Walden wore a hat with a bandana attached to the brim that obscured the harp from the listeners and from him while he was bringing it to his mouth.
  He played the opening measures of "Summertime".
  With my back to the listeners, I chose the harps and handed them to John, covering them with my hands.

  Comparison A was John playing 8 times from a set of 4 harps.
  Comparison B was John playing 8 times from another set of 4 harps.
  Comparison C was a machine playing a single note 6 times from another set of 4 harps.
  Comparison D was John playing 6 times from two CX12s; one with a black plastic cover and one with a solid brass cover.

  The combined scores of the group were no better than would be expected from random guessing.  Although there was expected variation, no one score stood out  to indicate exceptional listener accuity. We re-scored the results so that if the accurate identification of the materials was eliminated.   In successive plays, if the listener identified the same material or different materials correctly, it was counted as a correct answer.   The combined scores were still no better than random guessing.

  And what were the shortcomings in the SPAH test

  The criticisms were:
  The room ws not perfectly quiet.  The door was closed but there was some noise from the hallway.
  We should have used different materials in the same harp instead of different harps.
  Four materials in a group were too many to remember.
  The debate that started the seminar lasted too long leaving insufficient time for the comparisons.  (We had planned for John to play 12 times from each group of 4 harps)

  ....... that were corrected in the Buckeye test?

  A quick-change harp was used that allowed the combs to be changed within the same covers and reedplates.  .  
  More time was allowed.
  There were many fewer materials..only two, I think.

  Was the player tested? Blindfolded and asked to play a "supported" harp -- in a rack or on a stand so the heft/or lack of it and the shape would not give away the materials?

  John was not allowed to examine the harps but he must have known when he played the one with the lead comb.  We trusted John to do an honest and unbiased job.  I believe that he did.

  This materials issue could be an issue only perceived by the player, who then reacts to this "perceived" difference by playing harder, softer, lighter etc.

  The machine- played harps certainly did not have player bias or compensation. That is why a set of machine-played harps was included.

  The audience may not notice the difference between two keyboards made by the same company but the player would notice the feel if one keyboard had weighted keys (to feel like a piano) and the other unweighted keys (like an organ) and adjust the playing style to compensate.

  That is why you need a machine to play the instrument, to eliminate the human variables.  
  The extraneous variables may not have been perfectly controlled.  However they were orders of magnitude better controlled than just playing a harp in an amplified performance with accompaniment.  The criticisms arose after the seminar was over and after the results were announced.  

  Other than the fact that my metal combs are heavy and tight, the pastic ones are tight and the wooden combs seem a little less tight (leaky?) -- all my harps sound about the same (I think).

  I think you are right.  The difference is leakage, not materials.
  Vern



    ----- Original Message -----
    From: "J Compton" <jofjltn4@xxxxxxxxxxx>
    To: <harp-l@xxxxxxxxxx>
    Sent: Wednesday, September 17, 2008 2:24 PM
    Subject: RE: [Harp-L] More info about combs


    > Let me fire the first salvo in opposition to the conclusion of that study:

    "Lay on McDuff, and damned be him who first cries, 'hold, enough.' "

    > Just because you don't think you hear a difference doesn't mean it isn't
    > there.

    The question is about a ~perceptible~ difference.  Starlight is "there" in
    the daytime but it isn't perceptible.

    I'm sure that no one wants to cover all of the old ground, discuss the
    acoustical theory anew, and repeat the comparisons.  It is all in the harp-l
    archives.  For a number of years, things have stood about like this:

    *  Various musicians, especially those who sell combs of exotic material,
    continue to claim that comb materials have a perceptible effect on harmonica
    tone.  They cite testimonials and anecdotal evidence.  Some people believe
    them. The materials analogy with stringed instruments remains powerful, even
    if unwarranted.

    * Acoustic theory does not support such a claim.

    * Public comparisons under controlled conditions at SPAH in '97 and at
    Buckeye in '98 failed to support such a claim.  The Buckeye comparisons were
    designed to answer criticisms of the SPAH event.  I organized the SPAH
    comparison but was not present at the Buckeye one.

    * I have offered (and still offer) a $1000 wager that no one can reliably
    discriminate among different comb materials....
    .......... in a set of otherwise identical harps
    ...........in a public comparison
    ...........from the sound of the harps alone.

    If you can do it, you can win the $1000 and (better yet) see me "eat crow" !

    Vern
    Visit my harmonica website www.Hands-Free-Chromatic.7p.com 



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