An optical microphone assembly (2; 46; 62; 88; 114) comprising: a micro-electromechanical system (MEMS) component (4; 48; 64; 90; 116) comprising an interferometric arrangement, the interferometric arrangement comprising a membrane and at least one optical element spaced from the membrane; a semiconductor chip (6; 50; 66; 92; 118) comprising at least one photo detector; a light source mounted on or integrated in the semiconductor chip (6; 50; 66; 92; 118); a non-MEMS supporting structure; and an outer housing including at least part of the non-MEMS supporting structure, the outer housing defining an aperture (32; 58; 78; 104; 128); wherein the MEMS component (4; 48; 64; 90; 116) is mounted on the non-MEMS supporting structure and sealed to the outer housing such that the MEMS component (4; 48; 64; 90; 116) closes the aperture (32; 58; 78; 104; 128) and does not create an acoustic cavity between the aperture (32; 58; 78; 104; 128) and the side of the membrane that is in fluid communication with the exterior of the optical microphone assembly (2; 46; 62; 88; 114); wherein the semiconductor chip (6; 50; 66; 92; 118) is mounted separately from the MEMS component (4; 48; 64; 90; 116) on the non-MEMS supporting structure in a spaced relationship with the MEMS component such that the MEMS component is displaced relative to the semiconductor chip (6; 50; 66; 92; 118) in a direction perpendicular to a reflecting surface of the membrane; wherein the light source is arranged to provide light to the interferometric arrangement such that a first portion of said light propagates along a first optical path via said interferometric arrangement and a second portion of said light propagates along a second, different optical path via said interferometric arrangement such that at least one of said first and second portions is reflected by the reflecting surface of the membrane, thereby giving rise to an optical path difference between the first and second optical paths which depends on a distance between the membrane and the optical element; and wherein the at least one photo detector is arranged to detect at least part of an interference pattern generated by said first and second portions of light dependent on said optical path difference. a micro-electromechanical system (MEMS) component (4; 48; 64; 90; 116) comprising an interferometric arrangement, the interferometric arrangement comprising a membrane and at least one optical element spaced from the membrane; a semiconductor chip (6; 50; 66; 92; 118) comprising at least one photo detector; a light source mounted on or integrated in the semiconductor chip (6; 50; 66; 92; 118); a non-MEMS supporting structure; and an outer housing including at least part of the non-MEMS supporting structure, the outer housing defining an aperture (32; 58; 78; 104; 128); wherein the MEMS component (4; 48; 64; 90; 116) is mounted on the non-MEMS supporting structure and sealed to the outer housing such that the MEMS component (4; 48; 64; 90; 116) closes the aperture (32; 58; 78; 104; 128) and does not create an acoustic cavity between the aperture (32; 58; 78; 104; 128) and the side of the membrane that is in fluid communication with the exterior of the optical microphone assembly (2; 46; 62; 88; 114); wherein the semiconductor chip (6; 50; 66; 92; 118) is mounted separately from the MEMS component (4; 48; 64; 90; 116) on the non-MEMS supporting structure in a spaced relationship with the MEMS component such that the MEMS component is displaced relative to the semiconductor chip (6; 50; 66; 92; 118) in a direction perpendicular to a reflecting surface of the membrane; wherein the light source is arranged to provide light to the interferometric arrangement such that a first portion of said light propagates along a first optical path via said interferometric arrangement and a second portion of said light propagates along a second, different optical path via said interferometric arrangement such that at least one of said first and second portions is reflected by the reflecting surface of the membrane, thereby giving rise to an optical path difference between the first and second optical paths which depends on a distance between the membrane and the optical element; and wherein the at least one photo detector is arranged to detect at least part of an interference pattern generated by said first and second portions of light dependent on said optical path difference.