The Ar spectral lines are suppressed in Grimm-type glow discharge lamp atomic emission spectrometry (GDL-AES) by a double voltage modulation technique. The GDL is modulated between two voltage levels, typically 400 and 700 V. At the lower voltage level mainly Ar emission contributes whereas at the higher voltage level both Ar and atoms sputtered from the cathode contribute to the emission. The Ar emission spectrum at the lower voltage level is multiplied by a constant factor to scale it up to the same level of Ar emission found at the higher voltage level. This signal is then subtracted from the signal obtained at the higher voltage level by a lock-in amplifier to obtain the net analyte signal. The digital Kalman filter technique is also applied to background suppression; it is known to be the optimum filter for deconvolution of mixtures in noisy environments. The detection limits are found to be improved by nearly a factor of 10 with both double voltage modulation and Kalman filter techniques.