Sawsan - 9-30-2013 at 12:14 AM
Mar7aba everyone! =)
As you may have noticed I have been looking for an oud to buy, and in the process I have become a little familiar with the oud body and the names of
its different parts (or so I hope 
).
I have noticed that some ouds have one sound hole, some have three (one big hole, and two small ones up and down) and other that seem like they
don’t have holes or perhaps they are decorated, I am not sure. And I am actually still unsure whether or not an oud could work with no hole at all
(?)
Also, in terms of the strings, some have 7, others 5 (maybe there are other types) but at least these are the ones I came across so far.
So, my question then, is what difference do the number and shape of a hole (round or oval) as well as the number of strings make in terms of the
sound? I read the scientific explanation someone posted here http://www.mikeouds.com/messageboard/viewthread.php?tid=8488&pa... , but unfortunately, it was a bit complex for a beginner like me; perhaps if there were sound samples that would have been of great help.
Looking forward to your answers, guys! Thanks and salam!
jdowning - 9-30-2013 at 04:36 AM
The number of courses (single or double strings per course) can be 4, 5, 6 or 7 courses for the oud family of instruments - numbers that were
established in the historical development of the oud prior to the 16th C and still apply today.
Although I always use the term myself (to avoid confusion of comprehension) - in my view 'soundhole' is a bit of a misnomer as it does not 'let the
sound out' of an instrument but acts more as a 'vent' to relieve the air that would otherwise be trapped inside the bowl. However, the fundamental
frequency at which an instrument responds may be tuned by altering the vent area relative to the air volume of the bowl - usually to favour the bass
response of a particular course relative to the treble. This would have had an advantage at a time when duller sounding thick gut bass strings once
were the norm The number of vents or their shape should not make much, if any, difference - just the sum total area. I was able to demonstrate this
effect (the Helmholtz resonance) by running some trials on a guitar - including audio clips and related acoustic response waveforms as visible
evidence - as part of my thread that you have just referred to.
Note that the vents do not have to be placed on the soundboard but may be cut into the body of an instrument (so would not be apparent if an
instrument is viewed from the front as is the case with most depictions of old ouds in the iconography). Cutting vents or 'soundholes' into the sound
board of an instrument may also have an acoustic effect by locally weakening a soundboard. For example, some large bass lutes of the 17th C had a
conventional single sound hole with an additional small 'sound hole' located lower down on the soundboard on the bass side. I believe that the
function of this arrangement this may have served to favour bass response - not just by contributing to the Helmholtz resonance but by locally
weakening the soundboard.
Would an oud without any soundholes or vents work? I have not tried it (yet), but believe that it would.
jdowning - 9-30-2013 at 04:56 AM
Note that the audio clips referred to have now been deleted as part of a recent general purge of attachments posted on the forum dating prior to
January 2010. It may not be possible to reinstate the missing files (if I can find them among my records) as their size will likely significantly
exceed the current allowed size limit for attachments - but, if it is of interest - I could see if they might, with some editing, be readily
recovered.
However, the acoustic waveform images have been reinstated on the thread so should provide clear visual evidence without need for supporting sound
files.