Interchannel Phase
Final Display for the Interchannel Phase sequence
Introduction
When measuring multiple inputs, for example testing a beamforming microphone array, it can be useful to measure the phase response in reference to a single microphone in the array. This measurement is called interchannel phase. In this sequence, a six microphone array is measured. The user can select a reference microphone (defaulted in this sequence to DUT Mic 1), and it will measure the phase difference between this microphone and the five other recordings. A limit of +/-10° is taken at 1kHz, and the magnitude comparison of all measurements is also displayed.
Hardware Requirements
- Audio Interface – AmpConnect 621 or similar multichannel interface with 6+ inputs
- Source Speaker
Software Requirements
- SoundCheck 22 or later
- Module P/N 2021 – Transfer Functions
Hardware Setup & Calibration
- calibrate the Source Speaker according to the directions in the SoundCheck manual
- Before opening the sequence, in “Setup > Calibration > Import” and select System.cal included in the Interchannel Phase folder
- Select Yes to import calibrated devices
- Select No to All in overwrite existing devices
- Connect the 6 Microphones to Inputs 1-6
You are ready to start the sequence.
System Diagram
Changing the Phase Reference Microphone
DUT Mic 1 is set to be used as the reference when calculating the phase difference between inputs. This can be set to any other microphone in the array by opening step 5 “Ana – Interchannel Phase” and choosing the appropriate waveform in the “Stimulus” dropdown.
Further sequence development
Ways in which you could modify or further develop the sequence include:
- This sequence uses a six microphone array but could be edited to compare only two microphones, or add in as many additional channels as required
- The default 10° limit on 1kHz is arbitrary and can be set for any expected phase difference
Get Sequence
Download Interchannel Phase Sequence (zip file)
Download Interchannel Phase Sequence documentation (PDF)
