Electro-Tongue Drum Project


This is a project to build an electronic emulation of a Tongue Drum, also known as a tank drum or a hank drum.

I've described elsewhere what my motivation is to build this project. See my post “My 1st Project - Say Hello to the ‘Electro Tongue Drum’” in my blog for more information.

Project Brief

The main features of the electro-tongue drum should be:

* – A “tongue” on a tongue drum is the area that the player strikes to create a note. This is analgous to a key on a keyboard.


This is a long term project and I am very inexperienced, having just begun to learn electronics in April of 2021. Progress is expected to be slow.

The project is very much in the experimental phase. Having determined that the touch sensitive “tongues” are to use capacitive sensing, experiments are being conducted to learn about suitable material and software.


To date, these are the experiments that have been conducted:

Design Decisions

Number of tongues

Research has indicated that both eight and nine key tongue drums are popular, so it has been decided to construct the electro-tongue drum as a nine key instrument.

A nine key tongue drum has a central tongue and eight outer tongues around the circumference of the instrument. The following image illustrates the layout:

Proposed tongue drum layout

The eight key tongue drum has the same layout as the nine key version, except that the centre tongue is omitted. In a later version it is proposed to offer an option to switch the instrument into eight key mode by disabling the centre tongue.

Note order

The notes will be laid out in accordance with standard tongue drum practice.

To illustrate let us label the outer tongues according to their compass positions. The lowest note is on the centre tongue, then the notes increase in pitch is this order: south, south-west, south-east, west, east, north-west, north-east and finally north.

The following diagram shows the notes labelled in ascending pitch order from 1 to 9.

Proposed tongue drum layout with note numbers as just described in text.

Notice that no scale has been specified here, only the order in which pitch ascends (and by inference descends) across the tongues. The matter of scale and tuning will be addressed next.


First some facts about the tuning of acoustic tongue drums:

Since the electro-tongue drum will generate its notes artificially, there is no reason why a number of scales can't be supported.

Here's a possible roadmap identifying how such a feature may be added, depending on mode:

Stage † Audio Mode MIDI Mode
1 A single scale will be provided. A fixed scale of MIDI notes will be provided, for example C major ‡.
2 A choice of up to 8 pre-determined scales will be provided, along with a means of selecting the required scale. The default scale will be the same as the fixed scale provided at stage 1.
3 The user will be given the option of defining their own scales. These will be uploaded to the instrument either by SD card or USB. It is likely that a maximum of 8 scales will be able to be uploaded at a time.
The notes available for use will be restricted by the number of samples available. The notes available will be un-restricted. However, the user will need to limit the scales to those that can be realistically played by on the available virtual instruments.

† – The different modes may not reach the same stage of development at the same time. For example, it is looking likely that a MIDI instrument will be created before Audio Mode is developed.

‡ – This is not as restrictive as it first appears since some Digital Audio Workstations can translate received MIDI notes into other MIDI note values before sending them on to a virtual instrument, This means that any scale can be translated into different one.