Sony WF-C500 Help Manual page 82

Note
The Google app cannot be activated when you say "Ok Google" even when the Android smartphone's "Ok Google" setting is on.
When using the voice assist function, your voice will be heard from the headset through the headset's microphones (Sidetone
function). In this case, ambient sounds or the sounds of the headset operation may be heard through the headset, but this is not
a malfunction.
The Google app may not be activated depending on specifications of the smartphone or application version.
The Google app does not work when connected to a device not compatible with the voice assist function.
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