Mobile IxD

Most mobile devices have a portrait (vertical) display rather than landscape, though landscape (horizontal) displays are becoming more popular due to media devices and devices with QWERTY keypads. Both the orientation and the size and resolution of the display dictate the amount of content that can be shown. In practical terms, this affects the number of vertical lines available for menus and content (especially since the top and bottom lines are typically reserved for status and soft keys, respectively) and the space available for text labels and icons.

Audio on most mobile devices is sufficient only for voice conversations or short listening periods. For mobile communication devices, do not assume that the user has a headphone, let alone stereo headphones. Specialized mobile media devices can provide high-quality audio playback through headphones and may even have a higher quality on-board speaker. Playback-quality of various sound file formats can differ dramatically even on the same device.

Design for the orientation of the display (Note that a few devices have functionality that can dynamically re-orient the display – be sure to acquire a full understanding on the impact this has on designing a product for the platform)
Highly detailed visuals making use of subtle gradients and other visual effects are not recommended
When possible, reduce the complexity of the visuals – it is difficult to design a detailed 16x16 pixel or 24x24 pixel icon and to recognize what the icon represents; focus on providing basic shapes and colors as building blocks for the visual experience first, then the detail design second
High contrast visuals are always recommended for maximal usability
Always preview output on the actual target device(s), visual or auditory
Make audio cues brief and contrasting (similar to visual cues)

dave@mobileixd.com