Ultrasonic Directional Speaker With Focused Audio Technology Parametric Array Speaker For Museum - Instrument Parts & Accessories - AliExpress
Amazon.com: ELTEM/PROPA-U50 / Directional Loudspeaker, Directional Speaker, Ultrasonic Speaker, Directional Sound System for Museums, Exhibits, Art Gallery and Digital Signage – Black
Applied Sciences | Free Full-Text | Experimental Evaluation of Distortion in Amplitude Modulation Techniques for Parametric Loudspeakers