Shaku
Design

PVC Hochiku

Updated 4/24/08

The Japanese flute called a Hochiku is similar to a shakuhachi and is often lumped in with the shakuhachi. But Tom Deaver, in Japan, points out that the two are different and explains this difference.

Hochiku, or as some write, Hocchiku, flutes are always (except for the exceptions) one piece flutes, without the familiar connecting joint near the center of the length. Shakuhachi are almost always made in two pieces with the joint near the center of the length. Any shakuhachi made in one piece is called "nobe". The "be" of "nobe" sounds like the "ba" of "baby". "Nobe" can be translated into English as "total".

Hochiku are usually much thicker (fatter) and longer than shakuhachi so are commonly heavier than shakuhachi.

More often than not hochiku have no inlay material (buffalo horn, ivory, plastic, whatever) at the mouthpiece. NOTE: Instead of "mouthpiece" we'll say "utaguchi". The angle of the utaguchi plane of hochiku is closer to perpendicular to the length of the bamboo than utaguchi angles commonly seen on shakuhachi.

The size of the hole at the top of hochiku varies widely and can be quite large while the size of the hole at the top of shakuhachi is very nearly the same for all shakuhachi regardless of the length. The hole at the utaguchi end of shakuhachi varies a bit among shakuhachi makers but nowadays there is some consensus that things are generally easier when these open ends are all nearly the same in internal size. The external size varies widely, of course, depending on the fatness of the bamboo. What this means is that for shakuhachi with large bores there will be a thin wall partially closing the open end at the very top of the flute in the area where the shakuhachi is placed against one's chin. This little wall is called "iki kaeshi". "Iki" means breath and "kaeshi" means return. On some shakuhachi, and even hochiku, a thin ring of bamboo is inserted into the utaguchi end to replace part of the removed membrane and is then filed out in the area where the breath is blown over the edge, leaving a sort of crescent shaped partial ring of different color and texture. Sometimes material other than bamboo is used to reduce the size of the opening at the utaguchi, car body putty, resin, whatever.

Hochiku are mostly bamboo bores that have grown while shakuhachi are bamboo and some other material bores that have been made. 0n certain occasions for whatever reasons filling material is added to the grown bore while on other occasions for perhaps other reasons bamboo material is removed from the grown bore.

The membranes at the nodes of hochiku (on the inside) are removed to a lesser degree than the membranes at the nodes of shakuhachi. The node membranes of hochiku are usually visible while the node membranes of shakuhachi are almost never visible.

The frequency of the lowest normal note (neither meru nor karu), Ro, of hochiku is not adjusted to any specified frequency. The frequency of the lowest normal note of shakuhachi is, these days, nearly always adjusted so some specified frequency of the equal temperament scale.

The frequencies of the fingering positions for all notes, other than Ro, of the open hole hochiku scale (Tsu, Re, Chi, Ri, Japanese Inakabushi Yosenpo) are not adjusted to conform precisely to any musical scale, nor are they adjusted to sound a specified musical distance from the basic tone (Ro). These same notes of the shakuhachi are almost always adjusted to conform to the the musical scale currently in vogue, nowadays, the equal temperament scale with A4 somewhere between 440 and 445 hz, depending upon with whom one is talking.

Finger hole location determination is about the same for both hochiku and shakuhachi, being in most cases a sort of good guess full of hope.

Hochiku, as bamboo flutes and as a term used and understood by Kodama, are as long as or longer than about nishaku-gosun or rokusun. Some of the shorter big fat flutes used by Watazumi would not be hochiku according to Kodama. Further, what might be called semi-hochiku which have some but not a lot of filler in the bore (some call them "ji-nashi" = without "ji" or filler), could not be classes as hochiku by Kodama because of the added filler.

So, hochiku are a simpler, more natural flute than the shakuhachi. It could well be that 'improvements' to the hochiku resulted in the shakuhachi. Anyway, hochiku makers fiddle with the nodal membranes-- selectively filing them away to achieve certain desired tonal properties. Unfortunately, the process isn't easily reversible. You're working down the bore with special tools and if you go a little too far in the filing then what?

Well, you can probably see where this is going. The obvious answer would be tunable nodal membranes--and that's what we're going to build. Using gray 3/4" schedule 40 PVC we'll fashion a hochiku with special adjustable 'nodal membranes'.

Where do the nodes go? Many years ago, XELO, a radio station streaming out of Chihuahua, Mexico sold live baby chicks through the mail. Part of the spiel was, "You can grow 'em up, bash 'em on the head, eat 'em if you want. You can do anything you want wit 'em, cuz they yo' chickens." The nodes is yo' chickens.You can put a node any place you want. And put in as many nodes as you want.

Generally there are four nodes if we count the closely spaced nodes at the foot of the flute as one. Since a shakuhachi usually alters the location of the fourth node when the top section is cut and reconfiured this node location is based on aesthetics rather than the natural growth pattern. What are the natural growth nodal locations? Hard to say because culms for hochiku are selected by at least partially aesthetic criteria. But we're really only talking about one node--the fourth (see table below). Where should it go? It will be closer to the mouth than it's located in a shakuhachi. Let's say 24 mm. Again, you can put any and all nodal membranes wherever you wish. Make up your own natural nodal algorithm or measure a prized piece of bamboo and use those ratios.

Tunable PVC 1.9 (576mm) Hochiku
Holes
3/8"
Nodes
Shakuhachi
Nodes
Hochiku
1 -- 451
544
544
2 -- 400
484
484
3 -- 344
363
363
4 -- 283
216
192
Thumb -- 246
--
--

All measurements in millimeters and from the top.
This length (576 mm) with an integral mouthpiece plays C#.
So you can skip the nodal business
and just build a C# flute from these measurements.

Cut the pipe, fashion the mouthpiece, drill the holes 3/8" and mark the node holes along the underside of the flute. Drill and tap the node holes to accept 1/4" inch bolts. Insert the bolts and you've got a tunable hochiku--just screw these 'nodal membranes' in and out as you wish. That's the concept. You can easily alter location and number of nodal membranes along with their size and material. Small Parts, Inc sells nylon setscrews of different sizes and lengths. Air seal the bolts with Vasoline or wax.

There have been claims that adding outer 'nodes' to PVC will improve it tone. The theory is that PVC needs stregthening at nodal locations to achieve full resonance. If that's true then hose clamps would do the trick. We're all little more inclined to believe that adding mass at selected points along the course of the flute might effect it's resonance. In any event, the size and material of the bolts lend themselves to an investigation of the role of mass in this mysterious subject of 'resonance'.

Screwing bolts in and out at selected locations changes the volume of the bore which has a direct effect on sound and tuning. It's called perturbation and that's what filing natural nodal mebranes does. One interesting aspect of this design is that with a partner you can actually hear the shift in tone as the bolts are being adjusted during play--real time feedback.

These hochiku are inexpensive, simple to build and lend themselves to learning about nodal membrane tuning--besides worrying the neighbors. A different kind of adjustable flute is on the Throated Flute page.

See The Synthesis for a final flute design.


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