Abstract Noise power spectra of emission signals from an ICP discharge have been measured. Below 5 Hz the noise power spectra show a marked dependence on the type of nebulizer used. While a strict 1/ f character was not observed the spectra were clearly dominated by low frequency components. Above 5 Hz the noise power spectra were, broadly speaking, independent of the nebulizer. Distinct peaks were observed in the noise power spectra in the 200–400 Hz region. The exact position and intensity of these peaks were dependent on R.F. power, coolant gas flow rate and torch design. In addition the intensity of these peaks is dependent on the exact spatial region viewed by the spectrometer. The position of these peaks correspond exactly to similar peaks found in the acoustic noise power spectrum of the ICP. It is believed these peaks are the result of plasma rotation.