Voice Clarity Mic Speaker Coupling Factor Test
Test description
To ensure good Voice Clarity echo control performance, the acoustic coupling between built-in speakers and microphones must not be excessively high. This HLK test calculates the coupling factor from room impulse response measurements and evaluates whether the average coupling does not exceed a threshold.
Note
The speaker-to-microphone coupling measurement should be conducted for more than one device with acoustic characteristics representative of mass production units, to ensure that the measured coupling values are consistent.
Test details
| Specifications |
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| Expected run time (in minutes) | 1 |
| Category | Development |
| Timeout (in minutes) | 5 |
| Requires reboot | false |
| Requires special configuration | false |
| Type | automatic |
Test steps
To calculate the average coupling factor, the HLK test performs 3 consecutive measurements of the coupling.
- Render (in default mode) and record (in raw mode) a logarithmic sine sweep.
- Estimate overall acoustic coupling from the speaker signals (downmixed to mono) to each microphone.
- Align the speaker and microphone signals using the QPC (Query Performance Counter) timestamps.
- Apply a high-pass filter to all microphone signals for robustness against DC-blocking filters.
- Estimate the impulse response (IR) between speaker and microphone signals.
- Obtain fullband acoustic coupling from the IR coefficients.
Pass/Fail criteria
The calculated average coupling must not exceed the threshold.
Troubleshooting
If coupling value is excessive:
- Verify device is not in a configuration that produces abnormally high speaker-to-mic coupling factor (e.g., laptop in closed configuration).
- Verify that microphone sensitivity is correctly specified.
- Verify microphone and speaker are sufficiently far apart.
- Verify microphone sealing is adequate, with gaskets present, seated and compressed.
- Verify speaker loopback signal does not scale with volume control.
If coupling varies excessively between iterations:
- Confirm render processing is repeatable.
- Confirm DUT is not in a noisy environment.
- Confirm that the DUT is mounted on a stable base (no vibrations).
If your failure mode is not included on this list, search the error code in MSDN.
For generic troubleshooting of HLK test failures, see Troubleshooting Windows HLK Test Failures and Troubleshooting System Fundamentals Testing.
More Information
Parameters
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Additional Documentation
Tests in this feature area might have additional documentation, including prerequisites, setup, and troubleshooting information, that can be found in the following topic(s): - Device.Audio additional documentation and System.Fundamentals additional documentation.