Spectrogram of the total sound power level of the heat pump demonstrator from a run-out measurement at A7W55 from maximum to minimum compressor speed with extended frequency range. The main noise components are in the frequency range below 5 kHz. the components at 3 kHz and 7.2 kHz can be assigned to the compressor noise mainly exhaust by pressure pulsation. The VFD sounds have a minor contribution in this case, the carrier frequency of compressor drive is 6 kHz, the expanding sidebands correspondent to the switching frequencies, the VFD sound of fan motor is at 16 kHz.