When making the Ubi, we had three possible ways of indicating wake up:
- A tone / sound to indicate the device was listening
- A text-to-speech announcement
- LEDs to show the listening status
In the end, we did a combination of both LED and tone to show that the device was listening. The issue was that a tone could be very jarring especially if the person stating that wake up word was speaking quietly.
Today, at least on the Echo, there’s the option of also playing a wake up tone when then device is triggered. However, at least things could help this experience:
- Automatically adding tone when the noise is too loud.
- Detect when a user might not be looking at the device.
The latter can be done either through direction of arrival or potentially through a camera.