A well tool can include an oscillator which varies a flow rate of fluid through the oscillator, and another oscillator which varies a frequency of discharge of the fluid received from the first oscillator. A method can include flowing a fluid through an oscillator, thereby repeatedly varying a flow rate of fluid discharged from the oscillator, and receiving the fluid from the first oscillator into a second oscillator. A well tool can include an oscillator including a vortex chamber, and another oscillator which receives fluid flowed through the vortex chamber.