ï~~It is our intent to probe this hypothesis in a future
work. In any case, the results we achieved consent
to explain the doubts and the contradictions found
about this matter (see, for instance, Girardi
[19901).
4. Conclusions
In order to get a deeper knowledge of the
behaviour of pipe organs, in view of a more
realistic electronic synthesis of their sounds, we
undertook a detailed analysis of the characteristics
of pipe organs. Particularly, we studied how the
touch can modify the starting transient of pipe
organ sounds.
The results we obtained confirm that the notes of
pipe organs with short-distance mechanical
transmission have a starting transient strongly
depending on the touch.
Two of our analysis methods can be considered
innovative and they also confirm the influence of
the touch on the timbre during the starting
transient.
Nevertheless, this effect can disappear for notes of
stops with long-distance mechanical transmission,
and this can explain some of the doubts still
existing on this matter.
References
[Caddy & Pollard, 1957] S. Caddy & H.F. Pollard.
Transient Sounds in Organ Pipes. ACUSTICA,
vol.8, pp. 277-280, 1957.
[Dal Sasso, Debiasi & Spagiari, 1991] M. Dal
Sasso, G.B. Debiasi & G. Spagiar. Method for
Automatic Evaluation of Timbre and Fluctuations
of Pipe Organ Sounds. International Computer
Music Conference, 1991.
[Finch & Nolle, 19861 T.L. Finch & A.W. Nolle.
Pressure Wave Reflections in an Organ Note
Channel. Journal of the Acoustical Society of
America, vol. LXXIX-5, pp. 1584-1591, 1986.
[Fletcher, 1976] N.H. Fletcher. Transients in the
Speech of Organ Flue Pipes - A Theoretical Study.
ACUSTICA. vol. 34, pp. 224-233, 1976.
[Girardi, 1990] E. Girardi. Problematiche relative
all'Esecuzione su Organi Liturgici in Situazioni e
Modalita' Diverse di Alimentazione". III Convegno
di Organologia sul Tema: La Riforma de1'Organo
Italiano, Pisa, 1990.
[Lima & Oppenheim, 1988] J.S. Lima & A.V.
Oppenheim. Advanced Topics In Signal
Processing, Prentice Hall 1988.
tiune- time
1st
I
2nd
a
time
lOOms
lse
b 2nd
'I, _ _
lt
looms
time
Figure 1: starting transients of 1st and 2nd
harmonic of Zanin Principal 8!-C3;
a: slow touch; b: fast touch.
-4
SOOm.
500ms
Figure 3: starting transients of inharmonic
components of the same note;
a: slow touch; b: fast touch.
Figure 2: polar chart of timbre evolution (each dot
every 20 ins) on the starting transient of
the same note; a: slow touch; b:fast touch.
Acoustics
486
ICMC Proceedings 1994
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