I'm a software engineer but have very little experience in EE. I'm looking to design a device that takes as input an analog audio signal and adds a chime if certain keywords are detected in the audio stream. The input is otherwise directly passed through to the output.
Assume we have a microcontroller that can raise a line high when the right keywords are detected. What would the rest of the circuit look like?
- It seems like the simplest approach would be an analog circuit. Could we generate the chime with analog circuitry and just overlay it to the input?
- Otherwise it seems that we would need to pass the input through an ADC, have the microcontroller add the chime digitally and pass it out through a DAC (or use a DSP dedicated to this task)
- This will presumably add latency
- Additionally with this approach power is required for the device to work - ideally the fail-case for the device being off/out of power is just the signal passing through untouched
There are likely other considerations I don't see yet. How would you approach this problem?