UWE Bristol Engineering showcase 2015

Chris Cronin
Robotics BEng
Can Parametric Sound Be Localised To a Target Area Using Computer
Vision?
Introduction
Sound. Sound is all around us. One thing is for sure sound is everywhere, but
what if you could control the direction of sound using a camera and a very
unique speaker?
This project is an investigation into developing and testing a system
that can localize directional sound to a specific target area.
This system must be able to: detect and track people, allows selection
of a target, extract data about the target, use this data to move a parametric
acoustic array to point at the chosen target, and verify the target acquisition
using sensors.
With this complete system the hope is that an answer can be found to
the question above.
Background
Initial research showed no similar projects therefore research was conducted
in the two areas: Parametric Acoustic Arrays (PAA) and Computer Vison (CV).
The PAA concept has was discovered in the 1950s by Westervelt. The
direction sound produced is create using signal modulation and diffraction of
sound waves. The PAA used for this project was kit PAA produced by Kazumio
Computer vison has been around since the birth of computing in the
1960s. The CV disciplines needed for this project are face detection and
object tracking. Two methods where found that could achieve this:
Histogram of gradients and the Viola jones. The Viola Jones was chosen due
to reliability and accuracy.
Design
For this project there were two main areas of design, the software, and the
control interface.
The stand serves the purpose of mounting the PAA, but also to allow
the PAA to rotate 180 degrees. It also serves as a mounting point for the
power supply, and control interface. This stand was designed to be push fit
and be modular.
The software serves as the system to detect, track, select a target, and
then estimate the position of the target selected. This was created using
MATLAB, due to built in functions and a GUI was designed to use the
software and monitor the performance of the system.
Results
Testing was performed at each stage. The most important tests were the PAA
verification and the final system tests.
The PAA tests performed were done so to confirm the characteristics of
the directional sound. The results below show how the intensity of the PAA
reduces at a greater rate than that of a loud speaker as you move away form
the center line of the source .
The final test seek to find out if the conjunction of a PAA and computer
vison can localize sound to a target area. Below shows the table of final
results tat allows use to answer this.
Multiple People Stationary At 4 Points
Position (M) Angle (Degrees) Target
Person X Z CV Actual PAA Laser Switch
1 0 2 0.5 0 Yes Yes
2 0.3 2 9.2 8.53 Yes Yes
3 -0.2 2 -6.2 -5.71 Yes Yes
4 -0.5 2 -13.4 -14.04 Yes Yes
1 0 3 0.6 0 Yes Yes
2 0.3 3 4.8 5.71 Yes Yes
3 0.5 3 10.2 9.46 Yes Yes
4 -0.5 3 -10.1 -9.46 Yes Yes
1 0 4 0.4 0 Yes Yes
2 0.5 4 6.8 7.12 Yes Yes
3 1 4 13.8 14.04 Yes Yes
4 -0.8 4 -11.3 -11.31 Yes Yes
Project Supervisor
Dr Gary Atkinson
Project summary
This project was an investigation into the
conjunction of parametric speakers and
computer vision techniques to produce sound
in an isolated area, can sound be localise to a
target area? The purpose of this project was
to produce a prototype or a proof of concept
to answer the above question. This system if
proven to work could be used to
communicate with people privatively in a
public place. The two main areas of focus
were; Parametric Acoustic Arrays which was
used to produce the localised sound.
Computer vision which was used to detect,
recognise, locate and select a target.
Project Objectives
• Review related literature to computer
vison and PAA
• Create a proof of concept or prototype
• Design software to detect, track and select
a target for the system
• Measure and test the theory of the PAA
• Design a control system to move the PAA
• Perform final tests to answer to the title of
the project
Project Conclusion
The project objectives were fulfilled, that is to
say that sound can be localised to a target
area using computer vision. The results show
that the system is not perfect and show
opportunities for further work which are
feasible and attainable. If these opportunities
are utilised the system could function well.
This complete system could be used in
different applications from, creating a private
listen zone to entrainment sound systems.
The content of this paper could be used to
design similar systems or be used as an
example application for PAAs whilst bringing
the PAA functionality to a wider audience.