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Future Access Services

Clean audio

Some blind and partially sighted people may also have a hearing impairment. Many people with a hearing impairment have problems in understanding speech when there is a background sound, and other normally hearing people find background sound distracting. One possibility for a future access service would be to provide a 'clean audio' channel which provides the speech without any background music or other sounds. This probably requires a separate audio channel, and a modest amount of data capacity reserved for its transmission. With digital television, the cost of providing such an extra audio channel is modest, and the extra production costs are small compared to the number of people who would be helped by such a facility.

Speech input / output

Speech recognition:

STBs/TVs which can be controlled by the user’s voice are possible and would provide many benefits for a viewer with a wide range of disabilities. This would be of particular help to people with motor disabilities that make it difficult to reach for and operate remote controls. Speech as a means of selecting channels or interactive TV options via a microphone would also embrace a much wider range of people who might not consider themselves as ‘disabled’, such as elderly people with arthritis.

Speech output:

Set top boxes which can provide an audio output when the Electronic Programme Guide is ‘read’ from the screen are invaluable to those who find reading small print difficult. There is at least one set top box that provides this facility, and it would be useful if common standards could be achieved for the layout of EPGs so that a simple system of reading out the programme information (as an audio signal) could be agreed across all the European broadcasters.

Two-way services:

Potential future services might involve interaction between a disabled user and the broadcast service. One example of a future service might be to have subtitles, signing or AD available via IP services and synchronised with the broadcast programmes. If two-way interaction is implemented, all sorts of home security and alarm services could be made possible via digital TV.

Remote controls

Photograph of a remote controlTo interact with an interactive digital TV system a form of input device is required. Whilst, as previously mentioned, some applications are likely to need some form of a keyboard input, the TV remote control is likely to remain the main input device for digital television. Pressing buttons on the remote control whilst watching the screen becomes difficult for older viewers with presbyopia as the ability of the eye to focus at different distances decreases. Indirect controls, such as an infra-red remote control with an on-screen display, are now common but they can be difficult to use by people with low vision. Pre-programmable buttons for sets of frequent functions would speed up the process of selecting programmes or other services, and controls which are rarely used could be hidden under a sliding facade. The system must be error tolerant by providing a clear unambiguous button that permits the user to go back a step.

Recommendations on the design of remote controls from the UK Digital Television Group include:

Handset feel and comfort, size and shape

The handset should be of a size which can be held comfortably, and should be easy to manipulate using the right or left hand, with all buttons accessible when used with one hand. When the handset is placed on a flat surface, it should be operable with one finger. Larger handsets enable larger buttons, labels, and spaces between buttons making them easier to use for people with visual impairments and/or manual dexterity problems. In addition, they can be more comfortable to hold when designed to fit average human hand size.

The remote control (with batteries in position) should be well-balanced and heavy enough to hold comfortably, with its centre of gravity such that the remote control sits comfortably in the hand. The remote control material should be non-slippery and made of an easy grip material (without being abrasive) rather than smooth plastic that slips easily out of the hand. Shiny metallic (chrome) or smooth plastic materials that produce glare should be avoided, since these can make it difficult to see the buttons and labels.

The handset should be able to operate the target receiver from a wide range of angles; the area (both horizontal and vertical) in which the digital receiver is able to detect the signal from the remote control should be as broad as possible as direct aim towards the digital receiver can be difficult for some users. The selected infra red transmission protocol should ensure that there is no potential interference with other devices.

Button layout and design

Photograph showing the recording function keys grouped togetherButtons of the same functional category should be grouped together, since it is easier to identify, operate, and differentiate functions when buttons are grouped together by similar category (for example, numeric buttons, colour buttons, navigation buttons, volume up/down, additional services). Research has identified a benefit to additionally separating four main functional groups:

Spaces between buttons should be greater between functional button groupings than within them, as this makes buttons and groupings of buttons easier to identify and locate. Buttons within a functional group should be well separated, by perhaps 25% to 50% of the button width.

The most frequently used buttons should be placed in the most easy to find locations, with priority for inclusion on the handset based on frequency of use. More frequently used functions include stand-by, channel and volume adjustment, and the EPG service and related buttons (“OK” and “back”).  Button positions should conform to response stereotypes, with “programme up” button above “programme down” button; “volume up” to right or above “volume down”?.  The position of buttons relative to others can sometimes be indicative, or at least consistent, with their function, which can help people to locate buttons manually with reduced reliance on visual inspection. For example, at the simplest level, the relative positions of the arrow keys should be consistent with their direction (“arrow up” above “arrow down”, and “arrow right” adjacent right to “arrow left”), decrease/increase (for example, volume, programme number) can be suggested by relative buttons positions that are left/right, below/above respectively.

A raised dot (“nib”) on the number “5” button should be provided to help users find the centre of the numeric keypad. This is especially helpful for people with visual impairments who may rely on the “5” button to orient themselves on the remote control. This is consistent with the European Telecommunications Standards Institute (ETSI) standard for tactile identifiers ES 201 381 [17].

Buttons should be intuitively differentiable by size, shape, position and texture, making the remote control easier to use by touch alone. Buttons can be differentiated by size and shape.

Larger button sizes that are well separated are preferred by users both with and without visual impairments, making it easier to select a particular button without having to re-focus when switching visual attention between the television and the remote control. The most important buttons should be the largest. Button shape can be consistent with function (for example, the four directional keys for moving around the menus could be shaped as arrows pointing in their respective direction). Hollows in buttons (small circular centre) give clear ridges making them easy to find, comfortable to press, and easy to clean. Textures can be used to differentiate particularly important or frequently used buttons. Buttons should not be over sensitive so that they will not be accidentally pressed while the user is locating the button by touch.

The four standard colour buttons (red, green, yellow, blue) should be coloured correctly with no possibility of ambiguity and in the standard order, and should be the only buttons with these colours. Having more than one button with their background as one of the reserved colours (red, green yellow, blue) may confuse the user when the on-screen display gives options that require the user to respond using the colour buttons. For example, a user may press a red stand-by button instead of the red colour button. There should be sufficient contrast between the buttons, labels and background - higher contrast increases visibility. Solid background colours (rather than patterned) are desirable.

Toggle keys are useful in that they reduce the need for extra buttons, but when they are associated with more than two states (options) it may be difficult for the user to remember the order of the options, so they should only toggle between two states, and the state of a toggle button when it has been pressed should ideally be briefly represented by a suitable icon on the screen and/or some form of optional visual or acoustic feedback.

It is important, especially for people with visual impairments, to provide some form of feedback, preferably multi-sensory (for example, auditory/visual/tactile), to confirm any button press.

Photograph of an OK buttonButton labelling should be clear, legible and durable, with strong colour contrasts between labels and background. Sans serif fonts are easier to read, and abbreviations such as OK, TV  should be in upper case. Labelling terms should be unambiguous and easily understood.

For further information see the Remote Controls Guideline

Checklist for Remote Controls

Electronic Programme Guides

With the very large number of channels available on digital television, an important method of locating programmes and other services is through the electronic programme guide (EPG). The details provided on current and future programs make this an important feature, and on TVs with recording facilities it is also easy to record programmes merely by highlighting the wanted programme and clicking the ‘record’ button. But EPGs can present difficulties for viewers who are unable to read text information on either a screen or on a remote control, and this is where synthetic speech output from a receiver could be invaluable. Split screens and multiple viewing windows may obscure information and make details difficult to distinguish, so should not be used. Tables and other forms of visual information, such as programme channels being identified only by their logos, can be difficult for someone with decreased vision to decipher, requiring them to visualise and memorise the arrangement of information on the screen.

Customisation

Research into the use of interactive digital television by people with low vision indicates that different people require different settings, and that it is therefore difficult to optimise a screen design for everyone within a general population. By customising the interface or options available, regardless of the high functionality, the system could appear less intimidating and more accessible. Customisation could enable users to overcome many difficulties they experience by giving them control over functions such as the: text size; content layout; speech output; colour combinations; subtitles; audio description; signing; timeouts; reminders and alerts; mode changing capabilities according to level of expertise etc.

Photograph of a SNAPI card inserted in a set top boxOne means of achieving this could be through smart cards. The extension of the European standard about coding user preferences on a smart card EN 1332-4 would make it applicable to interactive digital TV and inter-operator/platform compatible. In this application a smart card  slipped into a digital TV would permit a special needs user to simply select their preferences (e.g. subtitles with a specified transparency or audio description), and re-set to default options for other members of the household. Such a system could also be beneficial in hotels so that the guest can easily obtain their preferred mode even though they were not familiar with that model of television set.

More sophistication could be incorporated when interactive television services (eg home shopping in a similar style to web-based services) become more widely available. The coding allows for facilities such as restructuring menus so that they can be selected by number rather than by highlighting the relevant item.

Since all integrated digital televisions in Europe must by law be fitted with a Common Interface (CI), and some set top boxes are also similarly fitted, the CI socket could provide the route for inserting a SNAPI card into digital TV receivers, via a simple card reader that fits into the CI slot. Users with low vision would like to be able to change the settings for text size, contrast, colour combination (e.g. avoid red and green), audio feedback from the remote control, speech output, speech input etc.

 

 



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