a wireless - communication device includes a user interface configured to receive audio signals ; a cryptographic module configured to encrypt the audio signals into a binary data sequence ; a generator module configured to : receive a bit pattern representative of the binary data sequence ; and generate a byte sequence representative of the bit pattern by generating a byte that is greater than the preceding byte when the current bit is of a first value and that is lesser than the preceding byte when the current bit is of a second value ; an audio codec configured to generate transmission bits by generating a transmission bit having the first value when the current byte is greater than the preceding byte and having the second value when the current byte is lesser than the preceding byte ; and a transceiver configured to convey the transmission bits to a receiver .