'Roommodes' or 'Eigenmodes' are areas in the frequency range, that love
to resonate. The resistance is much lower and therefore the energy
that is feeded into the room at this frequency range will last
longer. You can perceive this physical phenomenon in every room by
simply playing music in it. If your audio-source is able to induce
energy low enough in frequency, you will be able to recognize some
places in the room where the bass is louder and maybe some where you
think it does not exist. Even if you remain on one place the bass can
turn up and down in loudness depending on which note is played.
Why could one be interested in computing this room modes?
Even though those eigenmodes exist in every room, its possible to
reduce their negative effect on the musical enjoyment. Our intent is
to achieve a mode distribution that is as equal as possible.
Amroc shows the tune (musical notes) of every mode. You will see,
that - especially at the lowest modes - notes without any mode will
be followed by notes with multiple modes. This leads to
different reverberation times for different notes and is perceived as
different loundness of those notes.
A better mode distribution means less room-induced differences
The locations of modes are primarily depending on the dimensions of the
room, and so it's most effective if you are in the lucky position to
plan a room as a whole. It's not right, that you can eliminate the
problem of droning bass frequencies by splaying your walls. It will
reduce the effect of the axial modes by moving this resonant
frequency range but it's not sure, that the distribution of the modes
will be better with one or some walls splayed. However, it will be
much more difficult to compute them in advance.
Amroc is a room mode calculator that is not only displaying modes in
a table, but also shows interactive diagrams to help you understand
their distribution over frequency in an intuitive way.
What amroc is able to do:
It can greatly visualize the approximated modes of a rectangular
room. Please have in mind, that modes will change with every (larger)
piece of furniture.
Different possibilities to analyse a room's mode distribution are built in.
The Bolt-Area and Bonello-function are shortly described when you move your
mouse over them. Also the references to the scientific papers that introduced
them are there.
Of course you can copy the values of the table into an excel-sheet.
If you need even more tools to analyse room modes you can try my
older calculator that was written in java
As those java applets are not common
anymore I made this new html5 calculator but not all features have been built
in yet. Don't hesitate to write me
if you need something special!
Limitations of amroc
First of all it's just possible to compute rectangular rooms.
Fortunately most of our (intact) rooms belong to this group.
What does 'amroc' mean
I have used this title since the first day I
started to develop it. I thought I need a name and so I called it
Andy Melcher Room Mode Calculator because of the cool sounding
I've studied music science and I am now studying computer science. I
work as an audio engineer and java games developer in vienna, austria.
Why did you programm such a cool tool, excel-sheets are ok
When I started to read websites and scientific papers about
acoustics, I noticed that room modes are the most widely appeared
trouble maker in small rooms. A lot of people try to get help in
forums, asking 'where are the modes of my room?' and 'what can I do
to make things better?' They send around measures and get back values
of tables. I thought it would be better to type in those measures and
get screenshots, tables and all that stuff directly. Download a
amroc diagram and post it in a forum. Discuss your
possibilities...that's what amroc is for.