Mercedes are testing a new exhaust design on Wednesday aimed at making the sound of the new Formula 1 engines louder.
F1 boss Bernie Ecclestone is among those who are concerned the new turbo hybrid engines do not sound dramatic enough to please fans used to louder engines.
Mercedes are testing a 'trumpet' exhaust extension aimed at amplifying the sound.
The results will be analysed by governing body the FIA and discussed with teams before bosses decide whether to adopt it.
Also at Barcelona's Circuit de Catalunya on Wednesday, Williams development driver Susie Wolff is taking part in a full day's testing in preparation for her appearances in first practice at the British and German Grands Prix in July.
The 31-year-old will become the first woman to take to the track at a grand prix weekend for 14 years.
Wolff will complete a full aerodynamic testing programme in the car.