The way that a human user interacts with their computer, be it for music or for any other computerised task, makes a huge difference to the effectiveness of the human-computer system. One of the most obvious ways that HCI has affected technology is the use of hypertext and hyperlinks on the Internet. Without the interface of hyperlinks, using the Internet would be a slow and arduous task, and many people would soon give up using it in despair.
The interface, if it is well designed, can allow a more diverse set of people to use the system - the current 'windows' interface, while not perfect, is a lot simpler to use than the old command-line prompts, but still contains all the functionality (although the more complex parts may be more hidden from the user). This is especially true of users who are not computer-literate - as well as Electronics students being able to use computers, even English students can operate e-mail and produce word-processed documents.
The same effect can be seen in computer music - if the interface is good, then an unmusical person should still be able to make sound using it, but an experienced player should be able to make a variety of expressive sounds.
It is the word expressive that is often the problem for computers when dealing with music, since the logical computational abilities of the computer tend to be opposite from the spontaneous, improvised feel or a human performer. Harry Castle suggests there are two aspects of a musical interface that should be present for a good performance system:
Combining expression, action and a way to use imagination into a whole is no easy task, involving a mixture of computer science, psychology, ergonomics and various other disciplines. It is no surprise that the University of York HCI Group is made up of a combination of experts from both the computer science and psychology departments.
[Universities are traditionally the main research place for HCI, and without them it is possible that we would not have some of the interfaces we do. Generally industry is more likely to provide an interface that is satisfactory for what it does, rather than one designed specifically for users. DOS is a very good example of this, since only computer experts have a hope of being proficient in its use. It requires some input from non-engineers to develop a good HCI.]