Ultrasonic transducer and parametric speaker including the same

An ultrasonic transducer, comprising:

• a first diaphragm;
• one or more frame bodies extending in a longitudinal direction and bonded to the first diaphragm;
• and
• one or more ultrasonic vibrators attached to the one or more frame bodies, respectively, and opposing the first diaphragm with a space in between;
• wherein
• the first diaphragm resonates and vibrates in a direction orthogonal or substantially orthogonal to the first diaphragm in a phase opposite to a phase of the one or more ultrasonic vibrators;
• a dimension in the longitudinal direction inside the one or more frame bodies is equal to or greater than about four times a dimension in a short direction orthogonal or substantially orthogonal to the longitudinal direction inside the one or more frame bodies and is greater than a minimum dimension in the longitudinal direction of the one or more ultrasonic vibrators;
• and
• an average length in the longitudinal direction of a gap between an edge on at least one side in the longitudinal direction of an inner circumferential surface of the one or more frame bodies and an edge on the at least one side in the longitudinal direction of a surface of the one or more ultrasonic vibrators on a frame body side is equal to or less than about 1.3 times the dimension in the short direction inside the one or more frame bodies.