Edward Powell - 8-7-2009 at 05:52 PM
Does anyone know of any studieds done which attempt to determine the affect that the oud's size and shape has on it's tone?
I friend of mine recently told me he hear an oud with a very shallow flat back which had a great sound. Hard to believe - but then again, I didn't
hear it 
theodoropoulos - 8-8-2009 at 02:08 AM
Well make an experiment blow an empty bottle.The room of empty air and the diameter of the hole determine the frequency.This is something that
Helmhotz told with a type.look here...
if you fill with liquid the volume decreases and the frequency becomes more tremble.
http://www.phys.unsw.edu.au/jw/Helmholtz.html
the great sound of your friend does not determine the equalizer,but the quality.Of course it is more tremble in the soundcolour...it's just different
(not too close to an oud).
as far as the shape concerns it has to do with how well the bowl send the sound wave exactly to the soundboard hole to get outside and not trapps it
inside...
MatthewW - 8-8-2009 at 02:58 AM
Hi Edward- perhaps one of the oud makers in the forum can shed more light on your question. I've heard some great sounding classical guitars -compared
to an oud I guess we could say they have a more shallow back. maybe type of wood used, thickness/thiness of wood and bracing add to the equation along
with what theodoropoulos mentioned.
cheers - MW
Edward Powell - 8-8-2009 at 07:48 AM
thanks friends...
Yes from my own experience and experimenting and logical thinking I have understood that the larger the AIR SPACE mean the deeper the general tone.
What I am not sure about is: how does the SHAPE of that air space affect the sound.
...and also, How does the size and placement of the soundhole(s) affect the sound?
THEO has stated that a larger air space will give a deeper sound - and I think everyone would agree with this. But it is interesting what he suggests
about the size of the SOUNDHOLE, suggesting that a larger soundhole will encourage a deeper tone as well - - -
and finally Theo suggests that the SHAPE of the bowl works in conjunction with the size and placement of the soundhole in order to effectively PROJECT
the sound OUT of the instrument.
- - -
Just thinking aloud now, it seems to me that the sound is "made" primarily by the bridge and soundboard responding to the plucked strings. Then this
sound is allowed to 'develope' and be 'projected' THRU the air space, and OFF the back, and OUT the soundhole. ---therefore the primary tone
character will be determined by the pick, strings, bridge, and soundboard. Then that primary sound is amplified and "EQ-ed" by the body thru the
soundhole......
- -
I know there have been experiments on guitars with alternative soundhole positions and to my knowledge they have sounded great (guitars with
non-traditional soundhole placements). But what about an oud. Have there been ouds with non-traditional soundhole placements?
It seems to me that the shape of the ouds back truly encourages the sound to be projected thru the main soundhole--- but still I am curious.
I have heard ouds that have only the large soundhole and do not have the two small ones - and these ouds sounded somewhat less bassy and less loud
(and open). ...any thoughts?
thanks
Ararat66 - 8-8-2009 at 11:19 AM
Hi Edward
The bowl size encloses a volume of air to be oscillated by the sound board - I would imagine it would firstly denote a tone and the larger the deeper,
but I would imagine the soundboard bracing and bridge need to be resonant enough to be able to move that volume of air to produce a full range of tone
- if it were to be too weak because the soundboard is poorly or overbraced, it would be like a car engine in a lorry ... am I right in this?
I reckon the curvature plays a large role in focussing the sound, almost like an ampitheatre. Matthew made an interesting point, I've tried very
shallow guitars that sound fantastic - they tend to be pretty expensive so this reflects the luthiers art - but they can really project a lot of sound
and retain a full range of tone.
Cheers
Leon
jdowning - 8-8-2009 at 12:40 PM
Difficult to know the answer without many comparative tests.
Obviously, a larger instrument (longer string length) will have a larger bowl with a greater volume than a smaller (shorter string length) instrument.
Early surviving lutes from the 16th/17th C generally have flattened bowl profiles - particularly in the larger bass lutes or arch lutes (string length
around 95 cm) where the considerable flattening of the bowl is likely more of a physical consideration than acoustical (making the lute easier to hold
for the player). Smaller lutes of the 18th C generally had deeper bowl profiles - just to complicate matters!
The larger 16th C bass lutes also had relatively smaller sound hole areas. To my understanding small sound hole areas are supposed to accentuate the
bass response and large sound hole areas accentuate the treble but I would like to bet that no meaningful scientific tests have been done to verify
this notion.
As to the shape of the bowl somehow 'focusing the sound' through the sound hole - this idea has its attractions but - again- without scientific
verification is just unfounded speculation.
At the end of the day, it all depends upon what you - as an individual - perceive to be a good (or bad) sounding instrument.
Hatem_Afandi - 8-10-2009 at 07:24 AM
I find this topic rather intriguing. There is a lot of material covering it online and in books as well.
Also, well-respected luthieres like Maurice have their own prospective of the subject. However, I came to a slightly different approach:
- The best bowl wood is Syrian walnut. Similar performance is achievable using sisam wood, which is a special type of rosewood.
- Ebony wood causes the oud to be loud, but the sound is metallic
- The best sounding instruments have their soundboards made up of ONE PIECE.
- Floating bridge ouds are more powerful.
If we are to build an oud from scratch, it is better to get the luthiere his preferred type of wood.
theodoropoulos - 8-10-2009 at 09:21 AM
edward ,please i must correct you!!
a larger soundhole produces more tremble sound.
if you blow with your own mouth and shifting your lips from small hole to big one,you get a wha-wha like sound.
there where the mouth is larger you hear a tremble noise..try it !!it's funny!!
as far as the position of the soundhole concerns ,if we had put a mirror surfase in the inner bowl ,and a light from above,we could study optics and
find where the idol is placed.there would be the identical place for the soundhole!!
Edward Powell - 8-10-2009 at 12:24 PM
Thanks Theo!
You are really on to something here and have widened my understanding!
What I particularly love about the Turkish oud sound - and the sound I am trying to recreate on my ragmakamtar - is the very strong mid-range tone
(almost nasal). I know that mostly this is created by the 3rd brace on a Turkish oud always only generally being about 4mm high (Arab ouds are NOT
brace in this way - the 3rd brace in NORMAL size on arab ouds). The area of the 3rd brace is the area where the middle notes are amplified, so this
shallow 3rd brace allows those frequencies to resonate more freely. But what you are saying about the smaller soundhole giving more bass - really
makes sense because very near the 3rd brace are those two SMALL soundholes - and when I do that wah-wah trick when singing thru my mouth, I realised
that a middle sized mouth hole give that nasal sound. So those small holes must also be contributing to the oud's strong deep mid-range.
Also noteworthy is to compare with guitar --- oud has much more bass, and it also has those two small soundholes--- guitar does not have them.
Also oud has the round back... which I think contributes to the strong low midrange tones....
theodoropoulos - 8-11-2009 at 06:49 AM
THANKS my friend!!
i believe that only one person could help us here with this Turkish sound,and that is only Faruk.He is the one.We just tell our opinions only.But that
you say about the small holes is very correct.Another fact we did not mention is that the back bowl reacts sympathetically ,so the type of wood in the
right thickness,produces more mid range frequencies.....
take a look here,about guitars but is the same...
http://www.warmoth.com/Guitar/Bodies/Options/BodyWoodOptions.aspx