Emblem or logo? I'm a bit of a stickler for definitions: 'logo' obviously refers to 'logos', the Greek word for 'word' (and the ancients understood that 'logic' itself is tied to speech). So a symbol for an organization or an idea that has no letters or words is not a 'logo'; it's an emblem. The peace symbol is an emblem, and not one that I admire, as I've said. But the Voice Of America symbol depends on the organization's name, so it qualifies as a 'logo'. You might not guess that the paint-brushy, impressionistic oak tree symbol represents the UK's Conservative party, but if you knew of the existence of the Voice Of America, you could guess from the top part I show above.
The actual logo removes all mystery by spelling it out underneath:
And I like it. It has everything: the national colors. The representation of sound from a source -- from a speaker. The balance and upside-down symmetry of a good repeatable design: it's a pattern not just a signal: it has a beauty and order beyond the language it mimics. It's bold without being overbearing. It has almost an Art Deco angularity, confidence, and spareness. And the O, blaring its white light out beyond the framing letters, makes those framing letters more dynamic. Solid and unshakeable, yet dynamic: the USA. As a design, it's a complete success: I don't see how you could improve it.