I found a solution for you. It turns out the icon is not covering the full space that is provided.
Fixing this issue at least on chrome is adding the following css attribute to the iconset that comes with boothstrap.
.glyphicon-sound-dolby:before {
content: "\e190";
padding: .1em;
}
I would put it on the generic icon class so it effects the whole library, which if memory serves me right. Would be the :before, :after class names. Haven't worked with the library in ages, so try to just target the icons I would say.
:before, :after{
box-sizing: border-box;
padding: .1em;
}
Happy coding :)