The Multimodal Interaction Group website has moved. Click here to visit the new site
All about Earcons
Earcons were first developed by Blattner, Sumikawa & Greenberg , Sumikawa, Blattner, Joy & Greenberg , Sumikawa, Blattner & Greenberg  and Sumikawa . They use abstract, synthetic tones in structured combinations to create auditory messages. Blattner et al. (, p 13) define earcons as non-verbal audio messages that are used in the computer/user interface to provide information to the user about some computer object, operation or interaction. Unlike Gaver's Auditory Icons [73,74,75,76] which use natural, everyday sounds, there is no intuitive link between the sound and what it represents; the link must be learned by the listener. Earcons use a more musical approach than auditory icons. The following sections describe the construction of earcons from smaller units called motives along with descriptions of two different types of earcons. Some issues in learning and remembering earcons are discussed and then some systems that use earcons are given.
Earcons are constructed from simple building blocks called motives. These are
short, rhythmic sequences of pitches that can be combined in different ways.
Sumikawa et al. (, p 5) describe them thus:
They go on to say:
The most important features of motives are:
Sumikawa  defines rhythm and pitch as the fixed parameters of earcons and timbre, register and dynamics as the variable parameters. The fixed parameters are what define a motive, the variable parameters change it. Sumikawa put forward some general guidelines for use in the creation of motives. She gave general rules to follow but few precise instructions. In order to reduce the possible number of combinations of the above parameters, Sumikawa suggested some restrictions. Only seven time divisions should be used when creating rhythms and notes should be kept within a range of eight octaves of twelve notes. Semitone gaps should be avoided as they can create incorrect melodic implications; earcons should be musically neutral. She suggested that only four timbres should be used (sine wave, square wave, sawtooth wave and triangular wave) with three registers (low, medium and high) and a total of five dynamics (soft, medium, loud, soft to loud and loud to soft). Sumikawa said that motives should be no longer than three or four notes or they will become too long for the user to easily remember and may also take too much time to play when in combination. She give little empirical evidence to support many of these restrictions of the parameters. Work described later in this thesis attempts to put forward a more detailed set of guidelines based on experimental results.
As mentioned above, earcons are constructed from motives. Sumikawa (, p 64) suggested some principles to keep in mind when constructing an earcon: It should convey one basic meaning, be brief, simple and distinct from other earcons, and be easy to remember, identify and understand. Unfortunately she gave only general guidelines for creating earcons which means that following the above rules is difficult. She suggested three ways in which motives could be manipulated to create earcons:
These manipulations can be used in different ways. Blattner et al.  describe two types of earcons based on them: Compound earcons and family, or hierarchical, earcons.
Prof Stephen Brewster
Department of Computing Science,
University of Glasgow,
Glasgow, G12 8QQ, UK
Tel: +44 (0)141 330 4966
Fax: +44 (0)141 330 4913
Last Modified: 31 October 2002