"You also make the following defamatory attack on my authority by claiming ""So she [Janet Marlow] is a more authoritative figure than Viktor, at this stage.""  Your claim is based on nothing scholarly, only google hits and the fact that Marlow has self-published a method book. A method book, I might add, with proven misinformation contained therein. Among many errors in that book: In the front matter the author states falsely that ""Narciso Yepes [...] heard that there were four tones with less sustain due to missing sympathetic resonance on the six-string guitar"". That is, even though Yepes ubiquitously indicates eight (not four) missing resonances in various articles and interviews as referenced here as well as in his Speech of Ingression into the Real Academia de Bellas Artes de San Fernando delivered on 30 April 1989: ""The strings that I have added incorporate all the natural resonance that the instrument lacked in eight of the twelve notes of the equal tempered scale."" 

Despite discussing this last issue with you numerous times, you still made the folowing statement: ""there is no misinformation on the particular page to which I linked. Both sides are describing the same eight notes being provided by the same four resonant strings. Whether that is four ""resonances"" or eight is a non-issue.""  That is, even though eight clearly does not equal four and both sides are clearly not describing the same thing, you still defend your support of misinformation.

Even though I've explained this before, and my site explains it in detail, I will say it again:

The western musical scale has 12 notes per octave. On the guitar, Yepes observed, four of these when palyed on a treble string induced a unison resonance from a bass string. These four notes are E, A, B, and D. If any octave of any of these notes is played on a treble string, a bass string reproduces it in unison. If A5 is played, A5 is reproduced by resonance on a bass string. Yepes observed that the other eight notes do not have the same resonance. These are C, C#, D#, F, F#, G, G#, A#. By adding four strings to the guitar tuned a singular way (C, A#, G#, F#), all twelve notes of the octave, played anywhere on the treble strings, now have unison resonances from bass strings. If C#4 is played C#4 is reproduced on string 10 (F#). If F#4 is palyed, F#4 is reproduced on strign 10 by resonance. If both C#4 and F#4 ar played, string 10 produces both the pitch of C#4 and the pitch of F#4 simultaneously. This is a proven fact of acoustics.

If Janet Marlow claims there are only ""four missing resonances on the six string guitar"" (and in her book even attributes this to ""Narciso Yepes""), it is totally false. Yepes said eight missing resonances (C, C#, D#, F, F#, G, G#, A#) not four (C, Bb, Ab, Gb). Marlow knows that because she has (in Soundboard magazine) referenced an interview with Yepes (Snitzler, L. 1978. ""Narciso Yepes: The 10-String Guitar: Overcoming the Limitations of Six Strings"". Guitar Player 12: p. 26.) in which Yepes very clearly indicates which notes do and do not have resonance. Yet she has published at least twice the disinformation that Yepes added four strings (resonators) because four resonances were missing.

If you still have a problem understanding this, I am happy to meet with you and illustrate it on an actual 10-string guitar, since you've never owned/played one.
  

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