In this paper we study the advantages of a data transformation using time-frequency transforms (wavelets, in our case) in a wideband beamforming system. For this purpose, we simulate a target signal and interfering jammers that are impinging upon a microphone array in a noisy environment. The target and interfering signals are obtained from a speech database. The simulations presented show that the wavelet transform reduces the time of convergence, even though there is not an unique optimal wavelet filter; it depends on the speech signal. In this paper it can be also infered that the wavelet transform do not affect substantially to the quality of the output signal (evaluated with a speaker recognition method).