In this talk I will show you the theory behind parametric arrays what is involved in making your own low-cost directional speaker Parametric speakers are extremely directional speakers that produce audible sound by modulating an audible signal on top of an ultrasonic carrier. Commercial options have existed for a long time but are quite expensive for hobbyists. Licensed to the public under http://creativecommons.org/licenses/by/4.0 about this event: https://pretalx.hackerhotel.nl/2025/talk/9V7W9G/