[Harp-L] ACE Chromatic New wood inserts by Tom Halchak at SPAH

[Vern]

> On Jul 23, 2017, at 3:40 PM, Sheltraw <macaroni9999 at xxxxx> wrote:
> 
> Yes. It's not about subtle differences. So, are the differences spectrally subtle or not? Measure them. Surely somebody must have done so already, no?

Using software on my PC, I ran FFT spectrum analyses on the ten Big River harmonicas used in the SPAH97 comparison.  I still have the printouts but not the sound files or analysis data on media.  I don’t use this data to support my position on materials because it wasn’t witnessed and you have only my word that I used correct procedure. I made one second recordings of a machine blown harmonica note and submitted them to the FFT software.

I identified the printed results by number so that I could show them to people without revealing the materials.

No one could match the same material in two sets of reed plates.  No one could match two analyses of the same harmonica.  No one could correlate any material properties to any analysis. The materials included cement, aluminum, lead, open-cell foam plastic, closed-cell foam plastic, doussie wood, balsa wood, clear acrylic, and black ABS. 

I concluded that there were differences from graph-to-graph but they could not be correlated to material by graph content alone by me or others who tried.

There are 41 graphs and two pages of graph # - material keys

The graphs occupy half a page so could be included in about 23 scans.  I suppose that I could make them available if there were sufficient interest in seeing them.

> 
> Keep in mind that the human auditory system is nonlinear with respect to the relationship between what we report to hear and what the input is. For example, if two long pure sine waves are presented to the ear we report to hear overtones and sums and differences of the two frequencies (not to be confused with "beats"). 

About the auditory system, see “masking” on Wikipedia.

Vern