Some Shamisen are smooth on the inside, but others have an almost corrugated texture on the inside:
What is this called? What effect does this have on the sound? Does it make the instrument more desirable?
First response!
Referred to as the ‘herring bone pattern’ or ‘The Chevrons’ (-Luke) , that pattern is called Ayasugi. Apparently it has an effect on the sound. Maybe a little baffling for higher frequencies? Not sure. I don’t think it has a huge impact on sound, but rather more for looks.
The same ayasugi pattern is carved right under the soundhole of a koto. Only under the soundhole, where it can be seen. Nowhere else. 
This bolsters my suspicion that it’s primarily for looks.
I still put it on my shamisen though. I mean, as long as I’m making it, carving ayasugi doesn’t hurt the resumee, if you know what I mean. 
I have seen this also done on taiko drums too. I have jiuta shamisen with and without and I hear a big difference in sound quality. It seems to “sharpen” the tone. Tsugaru may not be as sensitive to this since it is so much more intense.
It seems to “sharpen” the tone.
Are the skins of the two shamisen about the same “age”? If one is newer than the other, or tighter than the other, that might affect the sharpness. Just one variable.
Even comparing it to other shamisen that sound “brighter” or “duller” the difference is large. Honestly I was shocked when I was able to compare them directly.
All high end shamisen I have seen have ayasugi. Considering the time and expense this adds to the shamisen and that it is completely hidden from view, I don’t think they would bother unless it really worked. My feeling is that it breaks up the echo inside the dou to give a sharper sound. Look at the walls of a sound studio. They are baffled too.
Very interesting.
If you have free time and a mic or camera at some point, would it be possible to compare the two shamisen (with ayasugi and w/o)? It would be very interesting to hear the difference.
Yeah, perhaps it’s not as noticeable for tsugaru shamisen, as the skin is so tight anyway.
Considering the time and expense this adds to the shamisen and that it is completely hidden from view, I don’t think they would bother unless it really worked.
Well, I watched a documentary about Japanese tansu makers. The maker put ornate designs on part of the structure that would be covered up by another piece, completely out of sight. For this reason, I figured it wouldn’t be too surprising if a similar kimochi was put into the shamisen this way. For tsugaru shamisen, ayasugi is only put on shamisen around 500,000 or higher, so I figured they wouldn’t skimp on the bling.
Ahhh… I guess my physics of sound knowledge is a little off. I figured that baffling would reduce the higher frequencies. Am I wrong?
I asked a shamisen maker about this once, and he compared it to the way high-end concert halls have irregular ceilings and walls to make sure the sound bounces around everywhere rather than bunching in certain places. I’m not really sure how exactly that translates to shamisen, though… If the sound moves around better inside, maybe it’ll move around better outside (and to listeners’ ears) too?
Kyle, I don’t really have sound equipment so I don’t know if I can make an adequate recording. I am busy this week but I will post something in a week or so if I can get a decent recording.
I definitely agree that there is a price effect too. Because these shamisen are more expensive I think they are better made with better materials. This alone would improve the sound.
There is a “small” difference in pirrice of shamisen with ayasugi and shamisen without ayasugi bori