The following link to the proceedings of a 1983 conference of Swedish guitar makers is quite interesting and there is a reference to the acoustic differences between plucking 'vertically' or 'in parallel' to the soundboard. A vertical 'pluck' producing a strong ,but short, tone and a parallel 'pluck produces a weaker but more sustained tone. Jonsson makes the point that the direction of pluck is normally a mixture of these two extremes and the resulting combination gives both the initial 'attack' and the ensuing 'sustain'. There is a lot of background research information including Chladni Interferograms. The whole publication is about 106 pages long! have a good read! Charles
http://www.speech.kth.se/music/publications/kma/papers/kma38-ocr.pdf#search=%22 Jonsson%20Acoustics%20for%20guitar%20makers%22 To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
