You install a picture-card app, and the child’s hand drops before it reaches the screen. A press lands on the card next to the one they wanted. Or it registers several times over and whatever they meant to say is lost.
A tablet screen is flat glass. Your fingers cannot feel where the buttons are, and there is no tactile confirmation when you press. Look carefully, aim, modulate the force — the design requires all three at once.
Concluding at this point that “the app didn’t suit them” would be a shame. Pressing accurately with a finger is not the only route to being understood. There are several reasons pressing can fail, and each has its own answer — which you can work through starting with the least effort.
This article is about that order.
Work through it from the lightest option
Koe Palette connects to MIDI devices
Some readers will be meeting the word MIDI for the first time, so let me start there.
MIDI is a shared set of rules for connecting electronic musical instruments to each other. It dates from the 1980s, and devices from different manufacturers will talk to one another as long as they support it. The digital pianos and synthesisers in a school music room usually have it, and so do the boxes of square buttons used for making music on a computer (these are called pads). You connect them over USB, or over Bluetooth.
Its original job is to send the message “this key has been pressed.” Koe Palette receives that message and plays the corresponding picture card. In other words, an instrument becomes a set of buttons for choosing cards.
What does that give you? You can assign one card to each pad. Hit the pad and that card speaks. There is no need to look at the screen and aim.
| Large and easy to hit | Pads are big enough for a palm or a fist, not just a fingertip |
| Responds to light pressure | They are instruments, built to sound at the gentlest touch |
| Survives being hit | They are designed to be struck with sticks. Force that is hard to modulate is not a problem |
| Easy to obtain | Available from music shops and online, and cheaper than equivalent assistive hardware |
| Lights up where pressed | On pads with lights, the one that spoke is lit up in response |
Pads are not the only option. A piano-style keyboard that connects over USB — a MIDI keyboard — does the same job. Each key becomes a button, so you can put “eat” on C, “drink” on D, and so on. The digital piano or keyboard sitting in the music room may work as it is.
Keys are long and narrow, though, so pads have the advantage on ease of pressing. A pad if the palm is doing the work, a keyboard if fingertips are available. The quickest route is to try what the school already owns.
But a pad shows you nothing
This is the biggest difference from touching the screen. A pad tells you nothing about which card it holds, whether you press it or it lights up. No picture appears, so a lit pad does not tell you what it was.
In practice, this means you will be sticking paper labels onto the pads. Pictures or words written out and fixed on with hook-and-loop tape or masking tape. It is handwork, and it has to be redone every time the assignments change.
Touching the screen has none of this overhead — swap the cards and the display changes with them. Choosing a pad means accepting that relabelling in exchange for the easier press. In day-to-day use, this is probably what tells most.
Limits and cautions:
· You can only hold as many cards as there are pads. Sixteen pads means sixteen words. There is a setting that turns one row into a category switch to raise that number, but it adds a step each time you switch
· Some combinations of device and tablet will not connect. Test on the device you actually intend to use before committing
When only one part of the body moves
Everything so far has assumed aiming at a target. Whether the hand reaches for a screen or a button, the person is choosing what to press.
So what happens when aiming itself is the difficulty? The hands may not move, but a chin can tuck. A head can tilt sideways. A toe may work. If any one part of the body can perform a press, that alone is enough to select.
Wait for the light to arrive, then press.
The cards on screen light up one at a time, in order. The light moves on by itself. When the card you want is lit, press a switch once. That card speaks.
The press happens once, and there is nothing to aim at. Because a single working point anywhere on the body is enough, this works even when very little movement is available.
This method is called scanning. It has a long history in the field of communication aids, and the Japanese Association of Rehabilitation Engineering’s guidelines on introducing communication devices list it as one of the input methods.
Let me put the two ways of pressing side by side.
Switches are chosen to fit the body: large buttons pressed with a palm, ones that respond to the lightest touch, ones pressed with a cheek or chin. Assistive equipment suppliers carry them.
But it means waiting
Scanning has an unavoidable weakness. You have to wait for the light to arrive.
Koe Palette lets you set the interval in seconds; the default is two. That interval, together with the number of cards on screen, determines the wait.
| Cards on screen | Two-second interval | One-second interval |
|---|---|---|
| 6 | 12 seconds at most | 6 seconds at most |
| 12 | 24 seconds at most | 12 seconds at most |
| 20 | 40 seconds at most | 20 seconds at most |
Wanting the very last card out of twenty means waiting forty seconds. Forty seconds for “I’m thirsty.” If the other person gives up waiting and walks away, nothing has been communicated.
So when scanning, start with around six. Add more once waiting has become manageable. The instinct that more cards on screen is more convenient works in reverse here.
A shorter interval is faster, but too short and the light passes by. The gap between deciding to press and actually pressing varies from person to person, so it is safer to start at a speed that is comfortably within reach and tighten it gradually.
If the switch doesn’t fit the body, none of it works
The most important part comes last.
Any method using a switch assumes that the switch fits the body of the person using it. If that is not right, no amount of tuning the app settings will make it usable.
The introduction guidelines mentioned above put it this way.
“Fitting the operating switch is indispensable; the system as a whole is constituted only when both the device and the switch are in place”
On choosing a switch, Kazuo Higano of Kawamura Gishi lists three things to look at.
| Quality of movement | “An unforced, smooth movement,” with “no superfluous motion requiring excessive effort” |
| Body part | “The dominant movement is the one operating the switch” |
| Posture | “A stable posture and limb position, whether seated or lying down” |
The part that moves most is not necessarily the best place. A movement that requires force will not last, and if posture collapses with each press, the same spot will not be reachable next time.
This judgement belongs to professionals such as occupational therapists. In a school setting, visiting specialist consultations and regional assistive technology advice centres are available. This is the one part best not carried by a teacher alone.
Summary
There is one thing I want to say. Not being able to press with a finger is not the same as not being able to communicate.
- Start by making the cards bigger and fewer. A setting is all it takes
- If the screen is the problem, move what gets pressed within reach. MIDI devices connect, so a music pad works as it is — though pads show nothing, so labelling them is part of the work
- Even when aiming is hard, one working movement is enough. Wait for the light and press
- But there is waiting. Twenty cards means up to forty seconds. For scanning, start with around six
- The switch has to fit the body. Ask a professional here
Which approach fits is something you only find out by trying. It rarely settles on the first attempt; expect to try a little, change something, and try again. That process is itself time spent getting to know the person.
I have introduced an app called Koe Palette here, but paper picture cards suit some children better, and are genuinely quicker in some situations. What matters is that what someone wants to say reaches the person in front of them.
I hope this is of some help to anyone struggling with communication.
Koe Palette (AAC app)
Card size and count, MIDI device input, and scanning. Core features are free
Android only for now / more about the app
· Guidelines for Introducing Communication Aids for People with Severe Disabilities (FY2010 revision) / Committee on Guidelines for Introducing Communication Aids for People with Severe Disabilities, Japanese Association of Rehabilitation Engineering, 31 March 2010
https://www.mhlw.go.jp/bunya/shougaihoken/cyousajigyou/jiritsushien_project/seika/research_09/dl/result/08-01c.pdf
· Supporting Communication Disability 4: Fitting Technology for Operating Switches / Kazuo Higano (KAWAMURA Group), Pacific Supply, 1 April 2019
https://www.p-supply.co.jp/topics/index.php?act=detail&id=535
This article reflects information as of 6 August 2026. App specifications change with updates. For fitting equipment and for what public support is available, please consult a professional or your local authority. If you spot something that needs correcting, please get in touch.