1D ultrasound transducer unit for detecting objects, contours or distances, comprising at least three ultrasound transducers for detecting objects, contours or distances and a control unit, wherein - the control unit is configured for individually controlling each ultrasound transducer, - each ultrasound transducer comprises a respective housing, a respective piezoelectric body arranged in the housing and a respective sound coupling-out layer, which is arranged at an open end of the housing, for coupling-out sound waves in a gaseous medium, - each ultrasound transducer is configured for the purpose of radiating and/or receiving the same frequency, - the frequency of the ultrasound transducer lies in a range of 20 kHz to 400 kHz, - each two ultrasound transducers directly adjacent to one another have a spacing from centre of the sound coupling-out layer to centre of the sound coupling-out layer of at most 10 cm or at most 5 cm or at most 2 cm, - the 1D ultrasound transducer unit has one sound channel per ultrasound transducer, - each sound channel has an inlet opening with a first cross-sectional area and an outlet opening with a second cross-sectional area, - each sound coupling-out layer is associated with exactly one of the inlet openings, - the outlet openings are arranged along a line and - a spacing from the centre of one of the outlet openings to the centre of a directly adjacent outlet opening corresponds with at most the wavelength in the gaseous medium or at most half the wavelength in the gaseous medium, - wherein the spacing between each two directly adjacent outlet openings is less than the spacing of the corresponding inlet openings and - a quotient of the area of the outlet opening to the area of the inlet opening has a value of between 0.30 and 1.2, - each sound channel has at least the length of the diameter of the inlet opening, characterised in that each sound channel is formed along a straight line, - the ultrasound transducers are let into a common support structure, - the outlet openings of all sound channels lie in a curved area or the outlet openings of all sound channels lie in a common planar plane, each ultrasound transducer has an electromagnetic screen lying at a reference potential, - the housing of each ultrasound transducer comprises a cylindrical metal cup and - the housing of each ultrasound transducer has a sound decoupling layer between the coupling-out layer and the metal cup. - the control unit is configured for individually controlling each ultrasound transducer, - each ultrasound transducer comprises a respective housing, a respective piezoelectric body arranged in the housing and a respective sound coupling-out layer, which is arranged at an open end of the housing, for coupling-out sound waves in a gaseous medium, - each ultrasound transducer is configured for the purpose of radiating and/or receiving the same frequency, - the frequency of the ultrasound transducer lies in a range of 20 kHz to 400 kHz, - each two ultrasound transducers directly adjacent to one another have a spacing from centre of the sound coupling-out layer to centre of the sound coupling-out layer of at most 10 cm or at most 5 cm or at most 2 cm, - the 1D ultrasound transducer unit has one sound channel per ultrasound transducer, - each sound channel has an inlet opening with a first cross-sectional area and an outlet opening with a second cross-sectional area, - each sound coupling-out layer is associated with exactly one of the inlet openings, - the outlet openings are arranged along a line and - a spacing from the centre of one of the outlet openings to the centre of a directly adjacent outlet opening corresponds with at most the wavelength in the gaseous medium or at most half the wavelength in the gaseous medium, - wherein the spacing between each two directly adjacent outlet openings is less than the spacing of the corresponding inlet openings and - a quotient of the area of the outlet opening to the area of the inlet opening has a value of between 0.30 and 1.2, - each sound channel has at least the length of the diameter of the inlet opening, - the ultrasound transducers are let into a common support structure, - the outlet openings of all sound channels lie in a curved area or the outlet openings of all sound channels lie in a common planar plane, - the housing of each ultrasound transducer comprises a cylindrical metal cup and - the housing of each ultrasound transducer has a sound decoupling layer between the coupling-out layer and the metal cup.