Drum Gum

An electroacoustic controller

realized by Jonathan Eccles

UPDATE, May 12, 2005: The pd patch now works to let 3 different chewing pressures control which of 3 sounds will play upon a user triggering the “play” button. Unfortunately, I have not yet found 3 suitable open/closed/midway hi hat soundfiles to plug into the sampler, so for now I'm demonstrating this control with oscillators. Still, it has allowed me to test how well chewing works as an interface. What's interesting is how less sensitivity one has with their teeth compared to their fingers. It is very easy to press an FSR to a very specific level, but with chewing, there are really only 3 different pressures my jaw allows me to give.

-- A little problem with my patch-- I'm letting all three sounds play whenever the user triggers, with just the chewing pressure determining how one gets a volume with the other 2 receiving 0 rms by a metronome. The big issue with this method is that even the currently activated sound gets a little click from 0 being sent to it by the metronome. I can't make the metronome send 0's at a slower rate so that a drum sample can play its full length, since this would cause multiple sounds to have non-zero volume at the same time if the user quickly changes chewing positions. I'll have to look around for a solution...

UPDATE, May 9, 2005: Well, I seem to have fried the only FSR CCRMA had left in the Maxlab, so I'm waiting for new FSRs I've ordered to arrive in the mail. Unfortunately, this means I am working with a barely alive FSR for my current Pd patch. This is very sad indeed, but usability will surely increase in the next week as I make a new prototype with working FSRs.

In a rare spatter of great news, I've taken the idea someone mentionned to me in class (sorry I'm forgetting who) and plan to mount a position-sensing FSR on a harmonica neck mount. With just a little padding and latex covering, this “Harmonica Gum” will be very easy to implement with a Pd patch of varying notes for different regions of the FSR. It all seems very fitting, what with the new freak-folk and psychadelic-folk movements out there, to have a folk guitarist wetting his lips on a synthesizer rather than an acoustic harmonica. The Animal Collective will be knocking on my door in no time, huzzah.

UPDATE, May 9, 2005: Very unfortunate news from the kind but unhelpful people at Hart Dynamics, the electronic drum company I've been in communication with. It seems that the hi-hat pedal I'm searching for-- that is, one that outputs a range from open to closed based only on an input voltage-- does not exist, and it has not been invented because my Drum Gum product would be the only demand for such a device. Alternatives can be found at the Hi Hat Page

UPDATE, April 25, 2005: Built a very pathetic model of the gum using earplugs and a condom (talk about found art!). It actually has an okay feel during chewing, but I believe the FSR was fried during the shrinkwrapping process.

Read about it on the Gum Page


My drummer friend Britton Caillouette had his left leg amputated when he was 15. Among countless obstacles being an amputee has presented to his life, his drumming is impeded by his inability to operate a high hat pedal. While he uses a prosthetic leg, his amputation is so high up that he has very little leverage with which to lift his prosthesis, therefore opening and closing the high hat in his kit is next to impossible.


“Drum Gum,” an electronic controller, operated by chewing, that to my knowledge will be the first of its kind. The user will chew on a gum like substance that, when receiving pressure, sends a signal to close the high hat, and upon release of this pressure will open it.

Where I stand...

  1. Find a device that takes an electrical signal to automatically open and close an acoustic high hat.

    -- I am investigating products by the electroacoustic drum makers Hart Dynamics. One of their devices is a pedal that, from what I can tell from its sparse online documentation, can be coupled with one of their high hats to operate opening and closing without true muscle-movement to physical manipulation energy transduction.

    -- Problem: I have been trying to get in touch with this company to investigate whether the Epedal (as it's called) can take electrical input as an activating signal rather than physically moving its pedal. Chances are, if the Epedal does not offer this feature, I can open it up and jack into wherever voltage controls manual high hat operation. Also, the pedal/hat set will cost around 400 dollars, which is a bit steep for this small-scale project.

  2. Controller devices

    -- Sensor will be a Force Sensitive Resistor, coupled with a regular resistor and constant-voltage source. The power source will have to be a battery mounted on a hat or headband. A wire will run from the FSR down to a ¼” connector that plugs into (optimistically) the Epedal.

    -- Problem: Since this device will be in the user's mouth, much work must be done to ensure safety and that the user's saliva does not contaminate the circuit. Care will be taken to cover every bit of wire, and the FSR will be covered by the gum material, which hopefully is or can be made water-resistant.

  3. Gum material

    -- As of now, my top choice for chewing material to cover the FSR (and protect it from damage by the user's sharp teeth) is the foam-like substance used for earplugs. It returns to its original shape when untouched, is firm but flexible, and doesn't seem to absorb water. More research must be done in this territory though.

    -- Problem: Getting ahold of a custom size of that material. Perhaps I can get in contact with an earplug company, or maybe I can speak with people at the PRL to see if they have other ideas for a gum-like substance that meets my requirements.

  4. For the future

    -- I would like to make this device wireless, though since I know nothing about BlueTooth at the time except that it sucks up a lot of power (and thus will require a bulkier power source) I will wait and see if my prelimary expectations are met during this quarter with time left to pursue wireless options. As I stand though, I will be happy simply to have a working, wired drum-gum-- as will Britton and our other band members, who will all benefit greatly from finally being able to play dance-punk with a working high hat.