buttons - What's the point in electronic devices beeping on keypress?

Many electronic devices, mostly cell phones, by default beep on keypress. What's the point in that?

Once a key is pressed their state is changed and that's reflected in the graphic interface anyway. Controlling those devices without looking onto screen is rather problematic, so the user has to look onto the screen anyway.

What's the extra value from those beeps?

Answer

To provide several channels of feedback:

• haptic: "I feel the key has been pressed",


• optic: "I see the key change its color" and


• auditive: "I hear the system felt that I pressed the key".

The change in the graphic interface is the effect of this action, and thus an additional, indirect form of feedback.

Why should different channels be provided at once?

• Accessibility. You cannot be sure that all of your users can see/hear/feel equally well, and it's difficult to know in advance in which context (noisy? bright?) the device will be used, so they should have the possibility to choose.


• Reassurance. New users may appreciate every little detail that confirms, "you are on the right track", because they use it for the first time, use it rarely, or just don't trust in technology.


• Surprise. Ask children, they will be excited of every way the system feeds back: "Yes, you did something, I understand you." And even as adults, when we use an object for the first time, and it confirms our actions in unexpected ways, this may remain an invaluable "first impression". _{(From a usability point of view, surprise is something you try to avoid, as everything ought to be "intuitive", "obvious". UX, however, would stress that a playful discovery may add to the product's value.)}


• It feels natural. When we interact with real objects, we always have different channels of feedback. _{(Grasping a bottle means: feeling that I touch it, feeling the resistance in my muscles, hearing the sound of cracking plastic, and seeing how it moves.)}


• Replacement/Ersatz. Especially touch-screen keyboards lack the usual haptic feedback, which needs to be compensated by other channels.


• Conformity to user expectations. If all mobile phones used an auditive feedback, you would need strong reasons not to give it - as you risk to lose customers that are accustomed to this sort of feedback and might class it as defect.

The sound can also convey additional meaning. E.g. short, high-pitched beeps for "OK", and longer, low-pitched beeps for "You currently can't type" or "This key isn't allowed here".

Scientific Background

Interfaces that have multiple channels of feedback are called multimodal (or multimedia), see papers about it.

• The different modalities should be selectable by the user. This is not only a matter of preference, but also of privacy. (Reeves et. al. 2004)


• The information the modalities convey need to be synchronised (redundant or complementary). (Reeves et. al. 2004)


• User input may be multi-modal as well (voice, gestures, etc.). (E.g. Oviat 1999, PDF)

The field of Tangible Computing explores its extreme case: digital interaction mapped to a real-world object. Digital information may be displayed through real objects ("Tangible bits"), or even allow direct manipulations through this object.