Background Caged canaries used to be common in mines because when they detect toxic gas they die quickly giving the miners a signal to get out before they inhale to many toxins. I always thought there was something ominous about the caged canary concept but just now found a way which I thought was good to put into writing.
The Idea The idea here is pretty simple, and maybe it's not good but if not I'd love to work with you guys to match an idea with this concept of a caged canary. So, the bird will only sing if its quiet for more than some amount of time. This means the bird should be contained in a place with constant noise. When the bird sings, any people nearby with the exception of those not conscious, sleeping, etc will become mute. If they're exposed to more than one instance of the song they begin losing other senses with the exception of hearing. I was also thinking it would be interesting to do something along the lines of having the song at first sound beautiful but turn into something which causes terror in the listener.
As always, criticism, feedback, etc are welcome. Thanks in advance for helping me improve on the idea!