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|How do AuSIM's products differ from generic "3D audio" products?||Most products targeted at 3D Audio are designed to give game-quality
performance, and are primarily used for computer games. AuSIM's products
are designed for mission-critical applications and offer substantially higher
standards of performance, both in terms of audio quality and perceived location
accuracy. This includes customized physical modeling of sound propagation
environments in software and higher speed and higher capacity hardware.
|What is physical modeling and how is it used to generate 3D audio?||Physical modeling is a method of synthesizing a real sound by using the
physical characteristics of the sound source (whether it be a voice, an
instrument, a machine, etc.), its propagation environment (such as air,
water, etc.), and the listener. The physical characteristics important to
3D audio include location of the source and listener, shape, orientation
and distance between the listener's ears, and sound absorptive / reflective /
transmissive properties of the space. When the most important of the physical
factors that affect the sound between the source and the listener are accounted
for, a signal passed through the model will appear to be originating from a
particular point in space.
|What technology is AuSIM3Dtm built upon?||AuSIM3D® is based on a dozen years of development by top
scientists, theorists and engineers in the field of audio simulation. Early
technology used DSPs to achieve needed levels of operation, but current
general-purpose processors have made it possible to achieve acceptable performance
without the expense and programming difficulties of DSPs.
|What is tracking?||Think GPS (Global Positioning Satellite) and then some. Tracking instruments
deliver the relative location of an object to a reference point. There are 6
possible degrees of freedom of movement that can be tracked. The obvious
degrees of freedom, X, Y, and Z, can be tracked with technology like GPS.
The orientation that your head faces at that x, y, z location is measured
in yaw, pitch, and roll – the last 3 degrees of freedom. Devices using
electro-magnetic, ultrasonic, inertial, and optical technology are available
that can track orientation.
|Why is tracking so important to AuSIM3D®?||In general, the ability of a person to localize sound is tremendously improved
when they can move their head and listen to the relative perceived position
of a sound from more than one orientation. The brain then uses these multiple
references to interpolate a much more precise location of the sound. By
incorporating head tracking into AuSIM3D®, the overall
effect of 3D audio and the general localization precision is much greater.
|Doesn’t hearing perception vary from person to person?||
Absolutely! Studies in the science of aural perception have identified
specific characteristics that help define these person-to-person differences.
A standardized set of tests can capture a particular head’s characteristics
in a Head Related Transfer Function (HRTF). This function defines how a
particular individual’s torso, upper body, head, and outer ear “shape” (or
filter) sound as it travels from the surrounding air into the ear canal,
and is generically referred to as “shape” or “shaping.” The HTRF can be
used to “filter” 3D audio to match the individual’s characteristic.
|Must I have my ears measured to use AuSIM3D®?||No. Humans have the ability to learn or adjust to hearing with someone
else’s ears. While “shaping” is unique to that particular individual, other
people can interpret similar directionality and localization of sound from
someone else’s HTRF filter. This directionality and localization is never
as accurate as when hearing with the proper filter. When we add or remove
headphones that “display” 3D audio with someone else’s ears, the brain
immediately starts retraining to hear properly. The retraining process
takes an indeterminate amount of time going in either direction, during
which time 3D perception is not optimal.
|Then what are the advantages of hearing measurement?||In mission-critical applications where an operator must hear and localize
a sound precisely and immediately, it is very important that the operator
hear with their “own“ ears, or HTRF filter. This helps to remove any possible
confusions, inaccuracies, or reversals (such as front to back) in the 3D
audio perceived by a listener, as well as eliminating the additional
inaccuracy during the retraining process.
Operators can have their personal physical characteristics captured in a custom HRTF filter sets. These can be precisely measured with AuSIM’s HeadZaptm system.
|Will AuSIM3D® work in a CAVE?||
Yes, the technology has been designed specifically for interactive applications
such as caves or other immersive environments. With the ability to integrate
head-tracking devices and deliver a dynamic perspective of the aural world,
alleviating the problem known as the “frozen perspective,”
AuSIM3D® technology enables correct correlation of all moving
graphics even with a moving subject.
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