There are a few reports online of people hearing piercingly high beeps when using Microsoft Teams. Some believe it’s related to people joining and leaving the call. I use a Focusrite audio interface and was very surprised to see high-energy sound showing in the VU meter LEDs during a period of silence in a call recently. So I captured the audio and this is what I discovered.
The beeps were in the 19479Hz range, give or take a few Hz. Not exactly 20Khz for some reason. And for some people with good hearing, it really Hertz! 🙄
Anyway, here’s the audio of that portion dramatically down-pitched in order to hear the timing of the beeps.
Play down-pitched audio sample
Also seen were some sound pulses that didn’t register even when down-pitched. They had lower energy distinct harmonic “hills”.
This intrigues me to say the least. There have been reports in the past of TV shows emitting such high sounds for specific devices to pick up on, sort of over-the-sound-waves device detection and telemetry. So why would Teams use close to inaudible pulses as a form of communication? It’s not like all speakers are of good enough quality to emit such frequencies, and the same goes for most microphones. So there’s no guarantee that it would be generated or picked up by most normal consumer audio devices. Which would suggest it’s some form of internal detection mechanism. But then why would an application like this use high frequency to communicate with itself? Wouldn’t it just be easier to use an internal API?
More questions than answers I’m afraid.