Bluetooth Headset Measurement
A sequence to test the send and receive performance of a stereo Bluetooth headset with a built-in microphone using a mixture of analog and digital channels.
This sequence tests the send and receive performance of a stereo Bluetooth headset with a built-in microphone using a mixture of analog and digital channels. The left and right earphones are measured simultaneously with a stepped sweep from 20 kHz to 20 Hz using two Bluetooth profiles: A2DP and HFP. The mic is measured with a stepped sweep from 8 kHz to 100 Hz using the HFP profile.
A short 1 kHz tone is pre-pended to the test stimulus which serves as reference tone for resampling and frequency shift operations. Post-processing resampling and frequency shift precisely synchronizes the stimulus and response waveforms prior to analysis. In this case, the HarmonicTrak algorithm is used for frequency response and THD analysis. A2DP frequency response and THD curves are displayed on the first display, followed by A2DP & HFP curves superimposed on a subsequent display. Lastly, the Bluetooth headset’s microphone is tested with HFP and its frequency response is shown on the final display along with the previously collected data.
- Head and torso simulator – B&K Type 4128C HATS or similar
- Bluetooth transceiver – Portland Tool & Die BTC-4148 Part # 5814 or similar
- Audio Interface – Listen AudioConnect Part # 4050 or similar
- Microphone power supply – Listen SoundConnect 2 Part # 4025/4026 or similar
- Power amplifier – Listen SC Amp Part # 4060 or similar
SoundCheck 15.0 or later
Test Set-Up for Bluetooth Headset Measurement
Setup & Calibration
When you first open the example sequence, you will likely encounter the following relink dialog:
Signal Path Relink Dialog
- Signal Path Relink: If any of the Signal Paths in this sequence don’t exist in your calibration, select “Add to System Calibration” and click OK.
- Import Calibrated Device File: You will then be asked if you would like to import the calibrated device file associated with the new Signal Paths. Click Yes to install the default calibration file (recommended) or No to continue and use or create your own calibration file.
- Hardware Channel Assignment: At this point, the System Calibration Table will open and you should assign appropriate input and output channels to the newly created Signal Paths.
You are now ready to run the sequence.
Further sequence development
This sequence has been designed for simplicity and has been written for a stereo channel headset with a single microphone. To further develop the sequence, you can:
- Add a USB barcode scanner to scan in the Bluetooth device’s MAC address
- Add logic to the sequence that allows you to test the microphone only or earphones only
- Add Limits steps for select values and curves
- Add Autosave steps to save selected data during sequence run