Spatial Sound for Computer Games and Virtual Reality - Game Sound Technology and Player Interaction: Concepts and Developments - page 306

Table 4. Perceptual Fields for MPEG-4 Spatial Audio

Environment Fields Source Fields

LateReverberance Presence

Heavyness Warmth

Liveness Brilliance

RoomPresence
RunningReverberance
RoomEnvelopment

Recent research has shown that the use of Head
Tracking reduces front-back reversals by a ratio
of 2:1 (Blauert, 1997) and there is evidence that it
assists in the externalisation of sources that would
otherwise be located 'inside-the-head'. Another
area where Head Tracking is helpful is in the
simulation and control of the Doppler Effect and
to resolve source-listener movement ambiguities.
Blauert (1997) terms this “persistence”:

too unreliable in a programming environment,
requiring compatibility with a wide variety of
device models. Therefore, there seems to be an
unusual scenario whereby 3D audio on mobile
phones continues to be of extreme interest to
interface researchers and API developers, but
the practical implementation of the technology
is stagnant in terms of mainstream consumerism.
This is set to change, however, with the emergence
of faster wireless networks, more powerful mobile
operating systems and the establishment of digital
media broadcast standards for handheld devices
(such as DVB-H).

In connection with spatial hearing, the term
'persistence' refers to the fact that the position
of the auditory event can only change with lim-
ited rapidity. Under appropriate conditions the
position of the auditory event exhibits a time lag
with respect to a change in position of the sound
source. Persistence must always be taken into
consideration when using sound sources that
change position rapidly. (p. 47)

Jsr-234

JSR-234, or the Advanced Multimedia Supple-
ments (AMMS), is an API initiated by Nokia and
developed under the Java Community Process. It
allows for more control over multimedia elements,
including the creation of 3D audio environments.
It is an optional supplement to the Mobile Media
API (MMAPI, JSR-135) designed for J2ME/
CLDC mobile devices. Refer to Sun (2010), Li
(2005) and Goyal (2006) for more information
on CLDC and MIDP specifications.
MMAPI is itself an optional low-footprint API,
implemented in MIDP 2.0, allowing developers to
create Java applications to playback and capture
audio and video in a variety of multimedia file
formats, perform camera operations, stream radio
over a network, generate musical tones and so
forth. A large number of mobile phone devices

Virtual spatial Audio On
Mobile systems

Although not widely known, there have been a
number of 3D audio solutions available for mobile
devices for a number of years. Despite this, manu-
facturers have been quite slow in implementing
Operating System (OS) and hardware support for
these audio APIs or only offer limited support on
a select number of devices. As a consequence,
third-party developers cannot rely on 3D audio
effects for their mainstream applications as it is