Peti uses hybrid FM synthesis technology and was developed primarily to emulate the sounds of the Harmonium, a member of the Reed Organ family, which is also known as the "pump organ". The Harmonium, in its smaller form, is widely used in north Indian music, and its full, sweet sound is often used in pop and rock music, but Peti is not limited to this instrument alone.

Peti is also capable of emulating a wide variety of reed organ variants, and can model timbres which resemble the many instruments in this family, ranging from from accordions to pipe organs, and even the famous melodica often used in reggae dub music.

Peti was designed to allow the user complete control over a simulated Bellows mechanism, with 11 different modes providing 'automatic' or 'manual' pumping, with appropriate modulation of the sound-generation engine's parameters.

It also features two separate 'reed bank' simulators, allowing it to create the widest possible range of reed organ timbres via its sophisticated hybrid-synthesis system. Peti's sound engine is also capable of emulating other key features of the Harmonium, including the body resonance of the instrument itself, the noise of air in the bellows and chambers, a 'musette' tremolo feature, and 'key coupling', which traditionally allows a single note to trigger two voices.