Acoustic spectra of sound emitted by metal active gas welding in series of thirty experiments with different technological parameters evidenced that about 50% of the acoustic energy generated during welding was transmitted by the waves belonging to the octave band with center frequency of 31.5 kHz. Since the time series of the sound pressure levels in this frequency band resembled that of the respective total sound pressure levels, empirical correlation equations of the two quantities and the welding current were fitted. Similar correlations were found for the A-weighting-filtered sound pressure levels. Other technological processes which accompany welding usually do not emit ultrasounds. Thus, a new method for the separation of the total sound pressure levels and the A-weighting-filtered sound pressure levels due to welding from the interfering background noise in a work environment, based on the measurements in the 31.5 kHz octave band, was suggested. The method was successfully applied to the separation of the noise due to welding process from the total noise which encompassed also the interfering grinding and hammering noises. To the best of our knowledge, similar approach to the assessment of audible noise from the sound pressure levels in ultrasonic range of frequencies has never been considered before. Contrary to well-known conventional methods of separation of shares due to different noise sources in the immission at a receptor location, the present method does not require a stable background noise level. In our opinion, this is its main advantage over the other methods.