Not really. The human ear can perceive down to 20Hz, and below that, you can&#x27;t perceive it actively, but the subconscious starts playing weird tricks [1]. Plus, you&#x27;d be limited to X Hz&#x2F;2 bits per second. Your better bet is getting something to drive an occasional chirp at 20k hz or so, which would be imperceptible to most people.<p>[1] <a href="http:&#x2F;&#x2F;skeptophilia.blogspot.com&#x2F;2011&#x2F;02&#x2F;ghost-in-machine.html" rel="nofollow">http:&#x2F;&#x2F;skeptophilia.blogspot.com&#x2F;2011&#x2F;02&#x2F;ghost-in-machine.ht...</a>