The acoustic device has a micromachined acoustic transducer element (15) an acoustically attenuating region (40) and an acoustic matching region (32) arranged between the acoustic transducer element (15) and the acoustically attenuating region (40). The acoustic transducer element (15) is formed in a first substrate (25) housing a cavity (19) delimiting a membrane (16). A second substrate (30) of semiconductor material integrating an electronic circuit is arranged between the acoustic transducer element (15) and the acoustically attenuating region (40). The acoustic matching region (32) has a first interface (32A) with the second substrate (30) and a second interface (32B) with the acoustically attenuating region (40). The acoustic matching region (32) has an impedance matched to the impedance of the second substrate (30) in proximity of the first interface (32A), and an impedance matched to the acoustically attenuating region (40) in proximity of the second interface (32B).
