A system for simultaneously detecting audio characteristics within a body, over multiple body surface locations (118 1 -118 6), the system comprising: a coherent light source, directing a plurality of coherent light beams toward said body surface locations (118 1 -118 6), said plurality of coherent light beams impinging on said body surface locations (118 1 -118 6); an imager, acquiring a plurality of defocused images, each image being of reflections of said plurality of coherent light beams from said body surface locations (118 1 -118 6), each image including a plurality of speckle patterns, each speckle pattern corresponding to a respective one of said plurality of coherent light beams, each image being further associated with a time-tag; a processor, coupled with said imager, said processor determining in-image displacements over time of each of a plurality of regional speckle patterns (126 1 -126 6) according to said acquired images, each one of said regional speckle patterns (126 1 -126 6) being at least a portion of a respective one of said plurality of speckle patterns, each one of said regional speckle patterns (126 1 -126 2) being associated with a respective different one of said body surface locations (118 1 -118 6), said processor determining said audio characteristics according to said in-image displacements over time of said regional speckle patterns (126 1 -126 2), said processor further compensating effects of the relative motion between said imager and said body (common motion), on the in-image displacement of each respective regional speckle pattern according to a difference between in-image displacement of said regional speckle pattern due to both vibration of said body surface locations and common motion, and compensated relative position and orientation between said imager and said body surface locations. a coherent light source, directing a plurality of coherent light beams toward said body surface locations (118 1 -118 6), said plurality of coherent light beams impinging on said body surface locations (118 1 -118 6); an imager, acquiring a plurality of defocused images, each image being of reflections of said plurality of coherent light beams from said body surface locations (118 1 -118 6), each image including a plurality of speckle patterns, each speckle pattern corresponding to a respective one of said plurality of coherent light beams, each image being further associated with a time-tag; a processor, coupled with said imager, said processor determining in-image displacements over time of each of a plurality of regional speckle patterns (126 1 -126 6) according to said acquired images, each one of said regional speckle patterns (126 1 -126 6) being at least a portion of a respective one of said plurality of speckle patterns, each one of said regional speckle patterns (126 1 -126 2) being associated with a respective different one of said body surface locations (118 1 -118 6), said processor determining said audio characteristics according to said in-image displacements over time of said regional speckle patterns (126 1 -126 2), said processor further compensating effects of the relative motion between said imager and said body (common motion), on the in-image displacement of each respective regional speckle pattern according to a difference between in-image displacement of said regional speckle pattern due to both vibration of said body surface locations and common motion, and compensated relative position and orientation between said imager and said body surface locations.