Średnia głośność and other 85,000 icons from Icons8 icon pack follow the visual guidelines of the operating systems: Windows, iOS, Android KitKat, and Material. PNG format is free up to 100x100 px. Icons are availble for download in PNG and vector (SVG, PDF, EPS, and more).
The main part of the logo is made of two connected shapes. On the left is a triangle with slightly rounded corners, and connected to it is a triangle facing left but cut in half so that the two shapes together look like a speaker facing to the right. Two semi circular lines are coming out of the speaker and represent sound waves.