Hi elmuedo,

this option is for the volume of the sound recording. To record loud sounds with minimised distortion, select "20dB". To record soft sounds, select "0dB". It is recommended to select an option while monitoring the volume indicator on the camera or the volume of the sound recording with headphones.

Sony Europe

ATT means attenuation. 0db = no attenuation: the sound arrives at its nominal volume. 10db = 10db quieter and 20db = 20db input attenuation. If the sound is too loud (eg: the microphone is next to a powerful loudspeaker at a concert) the sound will be saturated at the input. Lowering the volume with the recording volume will not necessarily solve the problem. But setting the ATT to 10db or even 20db will improve sound quality. So the rule is quite easy: in a quiet environment (eg noise from nature, forest, etc) leave at 0db. But in the middle of a city with lots of noise, try attenuating the input by 10db... if your camera allows you to plug in good headphones, you'll be able to extend the difference straight away. If the sound is saturated, you won't be able to "see" the quality of the sound using the meters. You need headphones. 🎧