'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 between notes.
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 acronym :)
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 too... 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.