The general aim in physics-based room acoustics modeling is to determine
how sound propagates in a room. It is a field that can be
approached from many different angles. People with background in
physics or mathematics tend to consider it as a problem of solving the
wave equation or other related partial differential equations. On the
contrary, those with background in computer science, especially in
computer graphics, prefer to think in terms of geometrical acoustics
where sound is modeled as rays, similarly as light is modeled in
computer graphics. The third identifiable group is formed of people
from the field of electrical engineering and signal processing. They
like to see room acoustics modeling as a challenge of designing
artificial reverberation filters that can be used to process audio
In addition to the physics-based modeling techniques mentioned
above, there is also an approach that is known as perceptually-based
modeling in which audio is processed to encompass acoustic
characteristics based on some more abstract description instead of
starting from room geometry and materials as is customary in physics-based
modeling. However, this area is out of the scope of this book which focuses
only on the physics-based approaches.
My personal background is in computer science, which may be
easily seen in the style of writing. Besides giving a general
introduction to each topic, the main emphasis is in algorithmic
descriptions of the techniques. Instead of going through all possible
derivations and theoretical analysis of the techniques each section
provides a collection of linked references to help the readers to go
deeper in the techniques as well as seeing their origins. There exists
plenty of other literature that covers those topics.
I can imagine several different styles of utilizing the book, and I
hope the readers will find even more innovative uses. The primary goal has been to
provide material that can be used as a textbook in courses teaching
room acoustics modeling. From that viewpoint, the book should benefit both
the teachers and students. The visualizations hopefully help
individual studying and at the same time those can be used in
classroom settings to help explaining various concepts.
The depth of the course should be adjustable. On the light end, just
going through all the visualizations with their instructions should
give a quick overview of the techniques, and that is often
sufficient. On the other end, it is possible to go through all the
algorithmic descriptions, and based on those it should be possible to
reach a level in which the students can replicate the techniques and
start experimenting with them by themselves.
One possible use scenario is to utilize the visualizations in
explaining the basic concepts of room acoustics without paying
attention to the actual modeling techniques. I believe that there are
plenty of courses that introduce the basic concepts of room acoustics,
and it would be great if this book could help in that task as well.
It is my hope that you will find the book helpful and that
it aids you in learning basic concepts of room acoustics and how to
model it. I am eager to improve the contents on a continuous basis, and
thus I am happy to hear any feedback or suggestions for improvements
in the e-mail address: firstname.lastname@example.org.
I like programming, and I have always liked it. In my current job as a
professor there is not too much time for coding such that it would start
to feel dull or routine. To keep up at least some skill level, I every
now and then try to devote some time for personal projects. In 2009, I
decided to learn a new language (Ruby), and implemented a small
application called 'SoundRad' that can be used to help teaching basics
of room acoustics. I used it in some presentations at conferences and
it was used also in actual teaching by my colleague Tapio
Lokki. People seemed to like it, and I started to consider whether it would
be possible to make a version that could be used by anyone and on any
platform. That led me to consider making an online version of
the tool expanded with textual explanations such that the result would
be an interactive text-book. The coming sabbatical would be an
excellent opportunity for such an effort.
Before the sabbatical started I spent some time investigating various
opportunities on how to implement an interactive book. It was quite
easy to see that the most accessible form of publication would be one
that could be read by a web browser. This decision limited the
the best option. The final confirmation for that decision came after
the colleagues in Lund, Sweden, released their great
Immersive linear algebra
interactive textbook, and one of the authors, Tomas
Akenine-Möller, told that they had taken exactly that path. So, I
started the sabbatical by studying yet another new language,
results are available in this book.
The starting point for structure and texts in this book was the
Overview of geometrical room acoustic modeling techniques
article I wrote together with Peter Svensson. This work was started in
2013 and it finally got published in 2015. The paper emphasizes
history and development of each technique and their mutual relations
whereas this book has a more educational focus.
I hope you enjoy it!
A large part of the book was prepared during my sabbatical in
2015-2016. I would like to thank
(Center for Computer Research on Music and Acoustics)
at Stanford University for hosting me during
Jenny and Antti Wihuri Foundation,
are acknowledged for their financial support that
enabled the sabbatical.
In addition, I want to express my gratitude to the following persons
for their feedback and/or support in preparing the book (the list is continuously updated, so, everyone is welcome to give feedback and it is appreciated!):
- prof. Jonathan Abel,
- prof. Tomas Akenine-Möller,
- PhD Jonathan Botts,
- prof. Tapio Lokki,
- PhD Sara Martin,
- MSc Kai Saksela,
- prof. Julius O. Smith, III,
- prof. Peter Svensson,
- Stack Overflow,
- prof. Vesa Välimäki.
The following parts utilized in the book are from external sources:
- fft.fs, Project Nayuki, MIT License,
- plotly.js, Plotly, Inc., MIT License,
- MathJax, MathJax Consortium, Apache License 2.0,
- The anechoic recordings by the Virtual Acoustics Group at Aalto University,
- Colormap values, MIT License,
All the other contents of the book are copyright by Lauri Savioja.
In addition, the site utilizes
to gather statistics on usage.
At the time of first publication of the book (May, 2016), only the
geometrical acoustics section is finished. All the other parts are
still under preparation. My sabbatical is ending soon, and this means
that I shall have much more limited time available for the book. The
other sections are coming, but at this time, I can't promise any
publication schedule for those.
© 2016 Lauri Savioja