I have basic knowledge on musical theory and I’m curious about the musical theory surrounding the shamisen. For example: why is the shamisen tuned the way it is? Japanese music seems to be mostly in the minor scale; why is that? Correct me if I’m wrong but I notice that shamisen music is mostly melodic and rhythmic while there is no (or barely) use of harmony in the western sense and in the sense of instruments like a guitar or a ukulele (i.e. chords, chord progressions, etc); I’m also referring to the bachido schoolhouse videos where Kevin and Mike Penny teach how to play various scales and such.
From Japanese Music & Musical Instruments by William P. Malm:
Since shamisen music is primarily vocal music there is no fixed basic pitch to which the instrument is tuned. It varies from G to D, B being used most commonly in transcriptions. It must be remembered, therefore, that the pitch of any transcription of shamisen music is arbitrary or, at the most, represents only the tonality of the one particular performance from which the transcription was made. Thus, there is no set pitch for a composition such as a song in B flat major or a symphony in D minor. There is, however a concept of “happy” and “sad” tunings which is found in our major-minor concept in the West.
I bought a shamisen VST for around a year ago and I was very gladly surprised that it came with a bunch of traditional japanese scales that I didn’t know of and don’t seem easy to find regular info about.
I even asked in some music forums for someone who could teach me japanese traditional music theory, I would have even paid for it but no one ever answered
If I find the time for it I’m planning to make something like a graphic reference of these scales because I could really need them when working with other instruments
Guitar Atlas Japan by Burgess Speed (published by Alfred, ISBN-13: 978-0-7390-4303-5) has a pretty nice overview of Japanese music theory. It presents a number of East Asian scales in western notation and has over thirty audio examples (most under sixty seconds).
While you are aware of “the use of harmony in the western sense”, it seems your questions are based on musical knowledge “in the western sense”. Rather, your question is what ethnomusicology deal with. It looks like “The Spirit of Tsugaru” by Gerald Groemer has some writing regarding Tsugaru shamisen music, like tuning and scales.
To clarify, questions like “why is the shamisen tune the way it is”, one must trace back to historical sources, and the development of the art and the instrument, for example. To say that “Japanese music” are in “minor scale” is to presume the music you referred are based in western classical scales. Off the top of my head, Japanese Gagaku (court music) has its own harmony (primary played by the Sho), and is also drastically different from regional folk tunes. The shamisen music we play are mostly arrangement of regional folk tunes, this alone cannot represent “Japanese music”.
Lastly, in my opinion, there’s in fact great sense of harmony (chords) in shamisen pieces, especially when the 1st and 3rd string are tuned in octaves. C-F-C and C-G-C tuning basically give you the root and fifth of C and F chord. 9th position of 3rd string (B flat) creates dominant 7 chord easily. 3rd position of 3rd string (E flat) conveniently act as a minor 3rd of C chord, or minor 7 of F chord. Plus, the buzzing 1st string gives an constant bass which acts as an harmonic support, whether you are aware or not. When analyzing harmony of western composition, the sense of hearing is taken into account as well. So you can say the sense of harmony is weak, but it has always been there. The teaching of various scales is to explicitly help playing western songs on shamisen.
Guitar Atlas Japan by Burgess Speed (published by Alfred, ISBN-13: 978-0-7390-4303-5) has a pretty nice overview of Japanese music theory. It presents a number of East Asian scales in western notation and has over thirty audio examples (most under sixty seconds).