[en] A new method to obtain one-dimensional map of ultrasonic wave speed is proposed. The method consists of insonifying a medium with an ultrasonic pulse and receiving the reflected echo on the same transducer used as transmitter and in another one placed adjacent. Each interface iluminated by the irradiated wave returns an echo to both transducers. Then by measuring the time-of-flight for each echo arrived on both transducers, the position of each interface, related to the transmitting transducer, and the wave speed existent between consecutive interfaces can be obtained. In the present work a phantom was made. Consisting of 3 layers: epoxi(9,9mm), acrilic (9.7mm) and pvc (10.2mm). The phantom was imersed in a tank filled with water, together with a holder with the 2 transducer in it. Using a digital osciloscope and microcomputer can implement the method proposed. The values calculated for the distancers interface-transducers have shown errors from 0.1% to and can be acceptable to a certain extent. On the other hand, all the obtained for the width of layers and for the of the US wave inside them are acceptable. The width of the of the echo from interface acrilic-pvc and it is necesary an exciting pulse with greater amplitude to enhance it. Results can be accepted as first approximation and encourage us to proceed exploring this method. (author)