This paper concerns the problem of localizing three-dimensional planar obstacles through multiple emissions and acquisitions of acoustic stimuli. The solution is based on the estimation of the Times Of Arrival (TOAs) of the acoustic signal at multiple microphones. These measures are converted into geometric constraints acting directly on the parameters of the planar reflectors. The combination of multiple constraints leads to the definition of a cost function. The minimum of the cost function are the searched line parameters. Some experiments show the feasibility of the proposed approach for the localization of single and multiple reflectors. This paper extends the technique in [1] to the localization of three-dimensional reflectors