https://mynoise.net/NoiseMachines/shrutiBoxDroneGenerator.php
Virtual Shruti Box — Online Drone Generator
Shruti boxes are used to produce a drone to play over during a practise session, or a concert.
shruti boxvirtualonlinedronegenerator
https://br.wiktionary.org/wiki/shruti-box
shruti-box - Wikeriadur
shruti boxwikeriadur