Web Program that Outputs Unique Audio Signal

I'd like to create a digital-audio-signal that works very similarly to a QRcode. When a receiver(microphone) understands the signal it returns the associated content, in this case HTML. Two web interfaces will be created. - First for uploading HTML and producing the unique audio signal - Second for scanning for the audio signal and returning the HTML ~Signal Generator~ 1. Web Interface that allows someone to upload an HTML file (or point to an html address) 2. A unique id is generated and acts as an index that locates the uploaded html file. 3. This unique id is encoded into a unique audio frequency that lasts 10seconds. (the idea is that when a receiver picks up the frequency it decodes it back to the unique id which is used to locate and return the HTML content) 3a. The Frequency Output must be between 16khz - 18khz and must be unique every time. 4. The 10second frequency is returned as an MP3 and downloadable via the Web interface. ~Receiver~ 1. Web interface that can enable the computer's microphone 2. Microphone listening for frequency between 16khz - 18khz 3. When it receives a signal in that range it is decoded and looks up the unique id to deliver the uploaded html content. 4. HTML content is loaded