A power converter controller includes a control loop clock generator to generate a switching frequency signal responsive to a burst load threshold, a power signal, and a load signal. A switching frequency of the switching frequency signal is above a mechanical audio resonance range of an energy transfer element and above an audible noise frequency. A burst control circuit generates a burst on signal and a burst off signal in response to a feedback signal and a burst enable signal to operate the controller in a plurality of burst modes. A burst frequency of the burst on signal or the burst off signal is less than the mechanical audio resonance range. A request transmitter circuit generates a request signal responsive to the switching frequency signal, the burst on signal, and the burst off signal to control switching of a switching circuit.