The SOPA technology allows you to create media art with the immersive sound and share it with the world.

On this site, we provide a Java program 'wav2sopa' that can be used to generate a panoramic sound stream from stereo .wav files so that you can make your own panoramic sound clips and save them to the local disk.

You can create a Web site with immersive panoramic sounds by using SopaJS (JavaScript library package).

QuickStart package is also available. By using QuickStart package, you can make immersive Web pages without writing program code.

To generate a SOPA file, you have to provide a pair of stereo WAV files that were obtained by a 4-track recording with a tetrahedral microphone system.

Download the Java program -> 'wav2sopa.jar.'

Tetrahedral microphone system

What you need is to develop your own tetrahedral microphone system that consists of 4 omnidirectional microphones. Four microphones have to be placed at the vertices of a tetrahedron as illustrated in Fig. 1.

tetrahedral microphone system
Fig.1 Tetrahedral microphone system
A tetrahedral microphone system consists of 4 ominidirectional microphones that are placed at the vertices of a tetrahedron.

Each side of the tetrahedron (microphone distance) should have length between 10 mm and 30 mm (the recommended value is between 10 mm and 20 mm).

Figure 2 shows an example of the tetrahedral microphone system.

Fig.2 Prototype of a tetrahedral microphone system
In this system, lavalier microphones 'audio-technica AT9903' are used.

You also need to have a multi-track audio interface with microphone amplifiers for the 4-track recording. You may use, for examples, ROLAND OCTA-CAPTURE, PreSonus AudioBox 44VSL, and so on.

You can also use a multi-track recorder (MTR) with microphone amplifiers (for examples, TASCAM DR-680, ZOOM H6).

Fig.3 Tetrahedral microphone system with an MTR (ZOOM H6)


Since there are 4 tracks, 2 stereo WAV files will be generated in the recording. Configure your system so that the signal flow is as illustrated in Fig. 4.

signal flow
Fig.4 Signal flow
The left and right channels of the WAV file 1 contain signals from Microphone left and Microphone right, respectively and those of the WAV file 2 contain signals from Microphone back and Microphone top, respectively.


Many of the commercial DAW softwares support multitrack recording and you can use one of them.

If you use a stand-alone MTR, you have to transmit the data to your PC from the MTR.

In a recording, synchronization of the tracks is crucial. If the synchronization latency is not small enough, little effect or even no effect is expected.

The synchronization latency may depend on either the software or the audio interface. If you use Roland OCTA-CAPTURE, for example, set the 'audio buffer size' to 'Min.' in the 'Driver Settings.'

Make the peak level several dB below digital full scale to prevent clipping.

Since the panoramic sound renderer on this site is for evaluation, there are the following restrictions.

When a 4-track recording is done, you are supposed to have a pair of stereo WAV files. Let's call them 'aaa.wav' and 'bbb.wav.'

As samples, a pair of stereo WAV files aaa.wav and bbb.wav are available. You can save them to the local directory and use them as the first WAV file and second WAV file (right click to save files).


Extract the files from the Java Archive file wav2sopa.jar, read 'readme.pdf' and follow the instructions so that you can generate a SOPA file out of the 2 WAV files 'aaa.wav' and 'bbb.wav.'

The line below is the command line to extract files from the .jar file.

jar -xf wav2sopa.jar

Enter this command line and press the RETURN key in command prompt.

Once the SOPA file is generated successfully, it can be saved to the local directory and can be used for free.

The main window of 'wav2sopa' looks like Fig. 5. The main window has 3 buttons and a combo box.

Panoramic sound encoder
Fig.5 Panoramic sound encoder


  1. Press 'Open WAV' button to select the first WAV file (corresponds to the microphones Left and Right) in the local directory
  2. Press 'Open WAV' button again to select the second WAV file (corresponds to the microphones Back and Top)
  3. Select the microphone distance (in the case of 'aaa.wav' and 'bbb.wav,' it should be 15 mm) in the combo box
  4. Press 'Start' button and wait until the process is done
  5. Press the 'Save' button to save data to the local directory

Please notice that the size of the SOPA file is comparable to the stereo WAV file.

Reproduction and distribution

If you have SOPA files in your local disk, you can play them in

If you send your SOPA files to your friends' PCs, friends of yours can also play them in

By using SopaJS, you can make a Web page full of immersive panoramic sounds.

Once you created your own panoramic sound (SOPA) files and their corresponding full-spherical video (MP4) files, why don't you publish them over Internet?

You do not have to write program code by yourself. You can make the Web page with panoramic sound and full-spherical video by using QuickStart package.

See quick for detail.

SOPA files that are generated by 'wav2sopa' can be used freely. However, if you publish them on your Web site or somewhere else, please give a credit to

Enjoy making panoramic sounds!

Create the immersive virtual reality experience and share it with the world.