The dependence of the intensity of subharmonic 1/2, of the sonoluminescence and of the thresholds for the emission of the subharmonic 1/2 and of light on the concentration of solutions of a tensioactive substance in distilled water has been obtained by using the pulsed cavitation technique. The weight concentration was varied from 10-3 to 10-6. There is a minimum in each of the incipient thresholds at a concentration of about 10-5. The subharmonic 1/2 emission indicates a larger number of bubbles in the solutions than in distilled water but this does not influence the intensity of the emitted light very much.
