2D- Auditory Mapping of Virtual Environment Using Real-Time
Customized Head Related Transfer Functions
by Carlos Ordonez
Abstract
The human brain is capable of localizing
sounds from events occurring in its surroundings. It is able to identify and pinpoint from
which directions the sounds come. This project will take advantage of that ability to
create a simple auditory map of a virtual environment with the use of Head Related
Transfer Functions (HRTF), which are the basis of
the most prominent techniques for digital sound spatialization. In this project a
synthetic virtual environment will be represented by a maze of vertical and horizontal
walls drawn on the computer screen using Matlabs Graphic User Interface (GUI)
components. In this virtual environment the subject will be represented by the computer
cursor. The objective is to have a blindfolded experimental subject traverse as much as
possible of this virtual maze, moving the screen cursor by means of the arrow keys,
without stumbling with its walls.
Instead of the visual display of the
maze, the subject will be guided by 4 spatialized sounds continuously simulated by the
system, appearing to originate at the front, the back, the left and the right of the
subject. These four spatialized sounds will be delivered to the experimental subject
through headphones and their intensity will indicate the closeness of the nearest object
in the virtual environment, with respect to the virtual representation of the subject, i.
e., the current position of the screen cursor, in the four corresponding directions. To
achieve this effect, the system will continuously determine the virtual distance of the
screen cursor to the nearest wall of the maze in each of the up, down, left and right
directions and it will modify the intensity of the spatialized sound coming from the top,
back, left and right of the listener, respectively. The intensity of the spatialized sound
in each direction will be proportional to the inverse of the distance to the nearest
object in the virtual environment. This process of real-time dynamic spatialization of the
four sounds will utilize the individual HRTFs of each experimental subject, measured prior
to the virtual navigation test.
The aim of this project
is the evaluation of the efficiency of navigation of a blind individual in an
environment that is dynamically mapped by continuous range measurements in pre-determined
directions, which are portrayed to the subject through the superposition of multiple
spatialized sounds.
Methodology:
The individuals
HRTFs are obtained using AUSIMs 3D-sound measurement equipment. The data collected
for 0, 90, 180, and 270 degrees of azimuth, at 0 elevation,
through this system are uploaded into Matlab. A GUI is created to represent
a virtual maze that the subject must navigate, updating his/her virtual location through
steps executed with the arrow keys of the computer. The system will evaluate the
navigation efficiency of each subject by keeping track of the total distance traversed by
the subject in the virtual maze and the number of times the cursor stumbled
into a virtual wall.
Testing Implementation:
In order to test this project the objects in the maze will warn the
user when he or she passes the pointer over the object hitting the wall. The
number of warnings will be counted to determine the efficiency of navigation during each
test.
Hardware:
The system will be implemented on a Personal Computer, and its
development will be based on the Matlab environment.
|