That's a false dichotomy (or straw man - maybe both).
Here's how I explain it when I'm doing communications training and someone brings up the worn-out (and incorrect) percentages (55/38/7). Firstly, to even understand those percentages, you'd need to know where they came from. I won't get into that (I do in training), but suffice it to say, it's a VERY limited basic study, which cannot be generalized much beyond its orginal scope. But here's how you can prove communication isn't those percentages:
- Tell a story without words, communicating exact details.
- Tell the same story in only words, communicating as much emotion as possible.
- Tell the same story with the audience's back turned (no body language) and in a complete monotone (no audible cues to emotion).
2 is much easier than 1. We get it in books all the time.
That's not to say the nonverbal (including voice inflection) isn't important (3 is difficult, at best).
@dvcochran mentioned earlier how much nonverbal can be a detriment (though that same negotiation would be all but impossible without the verbal, so we still can't place the nonverbal higher). And nonverbal - as well as inflection - exists even when we use text. We simply infer it from the text, rather than reading it directly from a person. This is why text communication so easily leads to misunderstanding of intent.