Compared with many other instruments, shakuhachi present a staggering amount of variety. For this reason, I’ll talk about the sound of most jinashi/jimori shakuhachi when compared to many jiari or “human-made” bore shakuhachi. In short, most jinashi sound rustic when compared to many jiari which sound more refined. We can really leave it at that. However, some wonder why this is. Taking an “everyday Zen” approach, we can simply look at what’s physically different between the two.
For example, if we compare the bore volume of an average jiari and jinashi of the same length, we will find that the jinashi holds more water, thus the bore is larger. Next, if we look down the bores we’ll see that the jinashi has more texture and is irregular, natural bamboo. Conversely, the jiari will have a smooth, uniform, human-made bore. For simplicity, we could say that jinashi are wide-rough and jiari are narrow-smooth.
The narrow-smooth bore of the jiari focuses the air and lets it flow. It will sound louder, cleaner, and feel easier to play. Conversely, the wide-rough jinashi will be less focused and will resist the air more. It will sound more mellow, dark, and textured. It will also take more air-pressure to play (AKA ‘back-pressure’, misnomer). This makes jinashi feel more engaging to play, though inherently more effortful when compared to the ease of jiari. With that said, the utaguchi blowing-edge and finger/tone-holes affect the timbre, playability/ease-of-play, and range. Everything’s interconnected. The most significant variable is, of course, us.