You might first want to try the simplest solution, which would be taking out the MicroSD card and making sure that it’s slot is completely free of all dust and debris that could be interfering with the card reader. Try blowing into the device to rid the area of contamination. If this does not work, then it could either be a faulty MicroSD card or a faulty card reader. Refer to the corresponding troubleshooting pages for further instructions and link guides.
Are you trying to listen to the audio on the goggles during playback, or from an external device? If you’re listening for the audio while watching back a recording in the playback mode of the device, the Spy Net goggles unfortunately do not have that capability. You are able to watch back the video, but the speaker on the device is not capable of playing back the audio. Be assured, however, that the audio is being recorded. In order to hear the audio from the device, you must play back the video on a computer. If you are viewing the recordings on a computer and the audio is still not playing back, then the problem is more than likely due to a faulty microphone. Follow along with this guide for information on how to replace the microphone.