Triggered Record Using Chirp Trigger and WAV File
A test sequence that demonstrates SoundCheck’s Triggered Record – Chirp Trigger function for open loop test of devices such as smart speakers, wearables, tablets, cellphones etc.
The purpose of this sequence is to demonstrate SoundCheck’s Triggered Record – Chirp Trigger function which allows you to test the output of devices without analog inputs such as smart speakers, wearables, smart home devices, tablets and cellphones. A stimulus WAV file is created in SoundCheck and transferred to the device under test, where it is played back and the response recorded in SoundCheck as if the stimulus were played directly from SoundCheck. The Acquisition step is triggered by the chirp in the stimulus file. Chirp triggers are more robust than level and frequency triggers which are susceptible to false triggering due to background noise.
The stimulus WAV file to be used on the device under test (DUT) may be customized in the Stimulus step. The stimulus default is an R40 stepped sine sweep from 10 kHz to 100 Hz, prepended with a 10kHz-20kHz chirp which is used to activate the trigger. The stimulus can be saved as a WAV when the sequence is run. The WAV will have the same sample rate and bit depth as set in your system hardware configuration. By default, the WAV file is automatically normalized to 0 dB FS in the autosave step, so the stimulus level is not important.
- The parameters of the sweep in the stimulus step are used when creating the WAV file. The duration of this stimulus must be considered in the “Time” field of the acquisition step. See page 2.
- The stimulus step must remain in the sequence and the stimulus settings cannot be changed without re-saving the stimulus WAV file.
- The stimulus WAV file used in this example is included in the sequence folder.
- Changing the sample rate or bit depth in the hardware configuration also requires re-saving the WAV file.
- WAV playback device with speaker or line output (smart speaker, wearable, tablet, etc.)
- Listen SCM 3 reference microphone or equivalent Part # 4002
- Listen Audio Connect audio interface/microphone power supply or equivalent Part # 4050
- SoundCheck Plus – version 17 or newer
- Time Selective Response (includes “chirp” log frequency sweep stimulus option) Module 2006
Setup & Calibration
- Calibrate the SCM 3 Reference Microphone as instructed in the SoundCheck manual.
- Connect the output of the mic supply to input channel 1 of your audio interface.
- Copy the default stimulus WAV file to the Device Under Test (DUT) or modify the stimulus parameters to suit your DUT. If you modify the stimulus file, proceed to step 4. If not, jump to step 5
- The sequence prompts you to save the stimulus waveform as a WAV file. Enter a name for the WAV file. The default location for the file is: C:\SoundCheck xx.x\Data\
- Load the WAV file on the DUT and make sure the WAV file plays properly.
- Set the playback level of the DUT to the desired level.
- Position the DUT so the speaker is at an appropriate distance from the reference microphone.
- Start SoundCheck sequence, click “No” to start acquisition and then play the WAV file on the DUT.