thats easy, that might require a custom texture though, considering there is no speaker texture with alpha channels I don't think, there is circle textures though, I have created my own custom cursor for my map, a murloc hand, so I have a general understanding of how 2d editing works, what you want is, a speaker picture, with a pulsating circle around it? growing bigger/smaller, hanging over the top of you're character, and the speaker is floating inside it? with the circle and speaker glowing? or just the circle?
wouldn't take too long.
EDIT: the speaker, even being a 2d image always facing us via billboard plane. can it be slightly 3d? as in rather then just the picture you made where it is a super simplified 100% sideways speaker, but more turned towards us ever so little as to make a sharp oval or
<()
shape? or do you prefer a
<| shape?