A method for near field authentication of sources using an audio transceiver computing device includes scanning a plurality of predetermined frequencies for a free frequency, selecting the free frequency from the plurality of predetermined frequencies, generating a periodic enclosed content message, generating a modulated carrier wave representing the periodic enclosed content message, and transmitting the modulated carrier wave at the free frequency. A method for near field authentication of sources using a microphone input of a receiving computing device includes scanning a plurality of predetermined frequencies to detect a signal using the microphone input, verifying, responsive to detecting the signal, that the signal includes at least one enclosed content message, and extracting a content from the enclosed content message.