I recently uploaded YouTube a video showing some hocketing instruments. This post provides a bit more detail on the instruments used in that video for anyone who may be interested.

The term “hocketing” refers to music making with rapid alternation between members of an ensemble to create melodies or interlocking rhythms, often with each member responsible for just one or two notes. A familiar example is handbell choirs, in which each player in the group plays one or two bells, and the melodies that emerge can be heard running up and down the line of players. The term has also been applied to musical styles ranging from certain types of early European choral music to a particular style of Pygmy music. The idea comes up a lot among makers of invented instruments, because we often find ourselves making a set of hand-held musical sound makers of one sort or another, but then find that we don’t have enough hands to play the set. The answer is to distribute the individual sound makers among a group of friends and make melodious and/or groove-oriented music by hocketing.

The first instrument type appearing in the video is the Sad Aggies. They’re the black tubes with floppy tails that players can be seen shaking. Sad Aggies are based on the commercially available sound instruments sometimes called Thunder Drums or Thunder Tubes. Thunder drums produce a sort of broad-spectrum roar, but the Sad Aggies refine the sound by means of several features that give them defined pitch. The ones in the video have toneholes which allow each Sad Aggie to play three notes, and with four players each playing a differently sized Aggie we get a nice range of available pitches. There’s a lot more than that to the design of these instruments, and you’ll find a fuller description here: Agitation Pipes | Bart Hopkin (the description of the Sad Aggies commences in the sixth paragraph of that article).

The second instrument type in the video is the Dinosaur Shakers. These are tuned shakers that have a lot in common with crotal bells or pellet bells. The hand-held tubes may be made of bamboo, aluminum or wood. Imagine a bamboo tube stopped by the natural node at each end, with a longwise slit running from one end over about a third of the tube length. The half-tube segments on opposite sides of the slit will behave like the two prongs of a tuning fork and can be tuned to a chosen note. The air within the tube has its natural air resonance pitch, and if you’re clever you can tune this air tone to match the fork tone so the two reinforce one another. If you now add some pellets to the inside (large enough that they won’t fall through the slit; added through a small hole drilled in the opposite end which is then corked), you’ll have a tuned shaker with a very distinctive, air-resonated tone. I made a tuned set of these and mounted them on springy steel arms for easy playing to create the instrument I called Dinosaur described here. In the process of prototyping and design for that instrument I made a lot of extra individual tuned tubes, and these extras make up the hand-held set hear in the video.

The third instrument type in the video is Après Baschet Air. These are hand-held tubes, 4″ in diameter, stopped at one end with a plastic cover. Fixed to the plastic cover is a 12″ glass rod extending outward. The glass rod is a friction-inducer: stroke it between moistened thumb and forefinger, or with a moistened cloth, and the friction will cause the rod-lid-tube assembly to speak. The plastic lid is carefully thinned and/or weighted so that the coupled system of the glass friction rod and the plastic lid produce a chosen frequency. The plastic tube is cut to the length that places its air resonance at the same frequency. The components are thus mutually reinforcing at the intended pitch, producing a strong, clear, warm tone. … At least, that’s the way it was when I first made the instrument, mounting a scale’s worth of these tuned elements on a large stand for easy playing. But time was not nice to the instrument. Several of the glass rods got broken one way or another – no surprise there – and the plastic covers aged badly, became brittle, and went out of tune as the instrument was for a couple of years left out in the weather. What you see and hear in the current video are some remnants of the instrument played as individual hand-held tubes. They don’t play as well as they used to; they’re no longer very responsive, and the tuning has become pretty much random. Yet it’s still, in its way, an impressive sound they make. You can read, see and hear more about the original instrument here: https://barthopkin.com/apres-baschet-air/ .

The fourth instrument to appear in the video is the Dabba Shakers. These are shakers made out of small stainless steel hot lunch containers. When you put pellets within, they produce two distinct, recognizable pitches. One is the sound of the pellets hitting the top of the container, and the other is the pellets hitting the bottom. The pitches vary from one container to the next, but the interval between top and bottom is typically not too far from an octave. You can tune the top or bottom by tapping lightly with a hammer. The resulting curvature rigidifies the surface, which raises the pitch. By judicious retuning of the top and/or bottom, you can tune the two an octave apart, which gives the shaker an unambiguous pitch-sense, not to mention a pleasing tone. By tuning different shakers to different notes you can, within limits, create a tuned set, and that’s what we’re hearing in the video. 

Last to appear in the video is a set of membrane reeds. These are tubes sounded by blowing. The sound is initiated by an air-gating system analogous to that of a reed instrument. In a typical reed instrument like clarinet or saxophone, the air flow from the player’s lungs is broken into a rapid series of pulses as the reed flexes to open and close over the mouthpiece opening. The pulsing frequency comes into agreement with the natural resonance frequencies of the tube to create a steady tone. For the membrane reeds, the function of the reed is filled by a stretchy membrane covering the tube opening. It’s set up with a blow tube in such a way that when the player blows, the membrane rises and falls to let puffs of air through, thus creating pulsing that instigates the standing wave in the tube. You can make membrane reeds in many forms, including as wind instruments with toneholes, as you can see here, here and here, but the ones appearing in this video are simple hole-less one-note tubes of varying lengths, some of them quite long, each intended to produce just one note.  

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