Acoustic OFDM data embedding by reversible Walsh-Hadamard transform

The manuscripts presents a novel acoustic OFDM data embedding by deploying reversible Walsh-Hadamard transform. The classical acoustic OFDM embedding method was replacing the high band of the acoustic signal with power adjusted OFDM data which brings two shortcoming of degrading the spectral efficiency of the acoustic signal for the listener and dependency to the acoustic carrier signal for estimation of high band envelope. Despite the classical method, the proposed approach not only preserves the spectrum of the acoustic signal, but also it is independent from acoustic carrier signal. The proposed approach encodes the OFDM data signal by a weighted reversible Walsh-Hadamard transform via a linear combination of acoustic signal samples and OFDM signal samples. The efficiency of the approach in data transmission as well as listener subjective quality of acoustic carrier signal for different level of background noise has been clarified, and optimum values of the weighting matrix has been obtained by the evaluation of implementation of the system.