100 Things #14: Compound Stimuli Offer Complete Test Flexibility

Sometimes a simple stimulus is not enough for your testing application. Maybe you need a stweep to test the range of your speaker, but also need to warm up the driver with pink noise. Or, maybe you are testing smart devices that require a wake word prior to recording. Perhaps you want to decrease testing time by using a lower resolution stweep at lower frequencies, while still retaining a higher resolution stweep for increased measurement accuracy in the higher frequency range. No matter your specific needs, SoundCheck’s stimulus editor allows users to create even the most complex compound stimulus with ease.

Compound Stimuli Offer Complete Test Flexibility

Testing smart devices with a compound stimulus

Compound stimuli are a great way to test smart devices, smartphones, or any device that requires a wake word for operation. By appending a stimulus with a wake word, the device can become active and record the test signal, allowing for automated smart device tests. Check out testing smart devices with a compound stimulus in our Smart Device Testing Seminar.

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SoundCheck allows you to build a custom stimulus consisting of as many different components as you need. You have full control over which parts of the stimulus are analyzed, so it’s easy to vary the stimulus across the test frequency range or use conditioning signals and wake words that are eliminated from the analyses.

One common application of a compound stimulus is to optimize a test signal for high accuracy and short test time. For example, when testing a loudspeaker ⅓ octave resolution can be used to sweep through the low frequencies quickly, and then 1/12 octave resolution is used at the higher frequencies to maintain measurement accuracy.

There are also many applications where it’s useful to use a conditioning tone followed by the test stimulus.

One use-case is to play a conditioning signal to warm up a speaker before a Stweep test signal is played. In this case, only the Stweep part of the signal is analyzed.

Another common application is to use the tone as a frequency trigger for triggered record acquisition, used in open loop measurements. When testing devices such as smart speakers, the stimulus is often prepended by a sinewave pilot tone, or even a chirp-based conditioning tone. These are not analyzed, but rather used to align the stimulus and response signals for analysis.

We might also use a frequency peak as a reference for performing frequency shift post-processing.

In telecoms tests, a conditioning signal may be used to trigger a voice activity detector before playing the signal for analysis. In some cases, a modulation segment may also be added to the tone. 

When testing voice activated devices, a compound stimulus allows a wake word to easily be prepended to any command or test signal.

These are just a few examples – what compound stimulus would you create with SoundCheck?  The possibilities are endless.