In a speed adjustment control method, amount of variation in speed \u0394V is given precedence, number of divisions of speed during speed adjustment and number of divisions of speed adjustment time are kept variable, number of divisions is made to be maximum at all time. The invention also relates to a method for the cosmetic treatment of keratinous fibres, as well as a use of the composition according to the invention as a shampoo. Various embodiments employing different output phase modulation approaches are set forth and time and frequency domain examples are provided. Sound source data is stored in the memory unit.