Information Technology Reference
In-Depth Information
These four principles are interesting as they enable the creation of earcons whose
structure is more closely linked to the level of depth of an item as well as its position
within a list. Indeed, the two types of scrolling (vertical and horizontal) are directly
represented by sound parameters (duration and melodic progression). We can,
however, criticize the absence of a real perceptive evaluation of the function fulfilled
by earcons, as well as a semantic representation of items that nonetheless still
remain very arbitrary (i.e. associate an item with a tone of one instrument rather than
another).
8.3.1.4.
Auditory scrollbars: sonification of the scrolling
The scrollbar is the element of the interface that enables us to scroll down a long
list of items or a document consisting of several pages. Several works have put
forward sonification of the scrollbar in order to represent the (relative or absolute)
position in a list and/or the scroll direction.
Brewster [BRE 94] thus proposes two principles for the sonification of scrolling
in a long document:
- for scrolling down or up, the use of a brief “beep” at a frequency of 130 Hz
(C3)
4
or 2093 Hz (C7)
5
respectively;
- to show the position in the document, the use of a continuous organ sound as a
background, the volume of which increases during 150 milliseconds when a new
page is passed. From the top to the bottom of the document, the pitch varies from
1975 Hz (B6)
6
to 130 Hz (C3).
The results of tests show a decrease in the mental work load (mental
requirement, physical requirement, temporal requirements, effort, performance and
frustration) and an improvement in terms of rapidity of navigation in the document.
More recently, Yalla and Walker [YAL 08] tested four different designs for the
sonification of scrolling in a long list of items (list of the names of an address book).
The earcons are followed by item announced by vocal synthesis.
Design 1 =
single tone
:
- each element in the list is accompanied by a beep;
- the progression of the pitch depends on the polarity of the pitch, i.e. ascending
or descending (both possibilities are tested separately);
4 C3 represents the 3
rd
note of C on a standard piano keyboard (88 keys).
5 C7 represents the 7
th
note of C on a standard piano keyboard.
6 B6 represents the 7
th
note of B on a standard piano keyboard.
