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. 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 with the possibility to save screenshots of the distribution of the modes for mailing, printing and analyzing.
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 :)

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. I have build in different possibilities to analyse a room's mode distribution. You can also copy the values into an excel-sheet.

Limitations of amroc

First of all it's just possible to compute rectangular rooms. Fortunately most of our (intact) rooms belong to this group. I also made some limitations concerning the rooms size, but I don't think/hope that you will reach them with an existing room you want to know the mode distribution from ;).

I've studied music science and I am now studying computer science. I work as an audio engineer and (thanks to amroc and my affinity to audio and acoustics) as java-programmer in a start-up combining all that former hobbies.

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 screenshot and post it in a forum. Discuss your possibilities...that's what amroc is for.

Development: It was in summer 2004. I decided to learn a programming language, but didn't know which one. I wanted (want) to learn 3 things at all costs: programming microcontrollers (for building cool tools like HUIs for mixing music (Assembler, C++), simply programming in C++ (for example VST audio plugins) or simply programming in Java. I decided to omit the hardware stuff for a start and thought about cool projects that could keep my enthusiasm alive. I'm always a friend of aiming high and so I had the idea to build a FEM (finite element method)in C++ or make a cool graphical user interface (GUI) for room mode calculations as my 'hello world'. I decided to go for java and if I wasn't a java-programmer now, I think I would have a HUI and a FEM too :D.
At that time it was an application (not an applet) but I thought there could be more people out there who could want to have the possibility to make those easy screenshots. So I made an applet (small applications especially for browsers), translated it into English and wrote some text for a page...and now I stop, because I have to download the VST-Api and/or buy a microcontroller :)

I hope you will like amroc too :) Have fun!