Abstract. An algorithm for voicing detection in noisy speech signal is proposed. This algorithm is based on the product of wavelet transforms at some scales called multi-scale product. The multi-scale product has the ability to reinforce the edge in the signal while suppressing additive noise. Motivated by the fact that unvoiced sounds are, in most important speech production models, considered as filtered noise, we apply the multi-scale product on speech signal for detection of voiced segments. In fact, the multi-scale product anneals the signal frames corresponding to unvoiced sounds and frames of silence, while it conserves speech periodicity for voiced frames.