I am working on a research project to test audio spatialization. The project involves playing audio on 35 different speakers. One speaker is randomly selected to play slightly different audio. Then, The test subject needs to pick out which speaker is playing the different audio. This process is repeated with different speakers.

I have already built a small scale version of this which has 10 speakers using a Focusrite audio interface. However, I need to scale the system up to 35 speakers. And the problem I am facing is a single focusrite only has 10 outputs. And the software I using only supports one device at a time. How do I get around this problem?

  • Please clarify what you mean by "the software I am using only supports one device at a time".
    – Mark
    Commented May 14, 2020 at 16:09
  • Upon reading this further, you have presented a requirement.. "I want to test audio spatilization", then presented a solution "I'm going to use 35 speakers", but you can't implement your solution. Please clarify further your original requirements around testing audio spatilization. What is it you want to achieve? What are you trying to discover here?
    – Mark
    Commented May 14, 2020 at 16:12
  • I am using the Python "sounddevice" library to send the audio data to the Focusrite. I am trying to test the ability of a person to determine where audio is coming from when there are multiple source emitting different sound. I have to follow a previous researcher's requirements. These requirement state that I have 35 speaker arranged in a specific way. I have to play the target audio once from each speaker in order to determine which ones it is easiest for the test subject to localize.
    – PetSven
    Commented May 14, 2020 at 16:35
  • Yes. All the speakers are playing at the same time during the test. One speaker plays the target sound that the test subject is looking for and the other speakers play a different sound.
    – PetSven
    Commented May 21, 2020 at 16:00

3 Answers 3


You randomly pick 9 of your 35 speakers you want to be able to "randomly" play something different. Don't tell your test subject which 9 you have chosen.You then connect the remaining 26 speakers to the 10th output of your focusrite interface. Bobs your uncle.


I found a hardware set-up that can do what I need. Two MOTU 24Ao (24 analog outputs) audio interfaces can be connected via Ethernet to create a single 48 output ASIO device. This requires some simple signal routing using the MOTU Pro Audio Control software. I am able to send audio to the two devices using the both the "sounddevice" and "pyaudio" Python libraries. More info on the MOTU 24Ao can be found here:

Motu 24Ao


Suggestion. Two channels of sounds, with two amplifiers. A switch using relays, the speaker either plays left or right channel.

You need this: stereo output, stereo amplifier, 35 relays (single pole, double throw, one position to left sound, other to right sound), a digital output card controlling which relay to energize.

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