Spoken conversation would then be the use of spoken communication to transfer ideas, information and opinions. It's the simplest and most effective way to get one's message across. After body language, it's the second form of communication that we learn, and in a way, it's the most infallible. When an infant cries for example, we know that it either a) wants something, b) is in uncomfortable, or c) none of the above and one needs to see a doctor; but we can't be sure of the exact problem. It's the reason a doctor asks a person to describe one's symptoms first; because spoken conversation is the fastest way to get information. Anyone who's played charades will understand the trouble it is to make people understand something purely using body language. Anyone who loves a pet will know how infuriating it is that one can't have a good one-on-one chat with a dog, cat, gerbil, or goldfish.
When we converse with someone verbally, we have a better chance of understanding that person; as compared to communicating via email or just observing their body language. Speaking is more emphatic than any other form of interaction. When we want to emphasize our point, we strain our voices and inflect more; the interest we take in a subject can be gauged by the speed at which we speak, or the way the decibel levels in our voice change. People give away a hundred different bits of info while they talk; other than just the words that they speak (Brennen, 2004).
It's a bit difficult to state the function of spoken conversation; other than the absolute obvious. We use spoken conversation to communicate cheaply (doesn't require a monthly internet charge, or permanent markers); easily and fast; and to get our idea across most effectively. The voice, like the body, doesn't have a language barrier. The way a person intonates, and the rise and fall of his voice can get his message across even if he doesn't speak your language. The dynamism of speaking is such that we never ever pronounce a word in the same way twice (Wiki Answers). Our brain is able to recognize different sound patterns and give meaning to them. A simple word "Yes" can be used to signify approval, doubt and even a "No" if spoken with different tones. In any other form of communication, yes would just mean a 'yes'. So if one is speaking, it's absolutely necessary to pay attention, otherwise you might never know what you're getting into. Spoken conversation, because of its chances of ambiguity, strains one's mind more than any other form of conversation; and that includes written conversations with one's English Literature professor.
And lastly; no form of conversation is as enjoyable as spoken conversation. Wit, banter, and irony are all exchanged verbally. Arguments, heated discussions, and rants on politics and sport are as much a part of our lives as gossip exchanged on the telephone. The advent of the 'Talkies' finished off silent movies; and unemployed many silent movie actors. And now, I doubt we can even imagine sitting through a 2 hour movie that doesn't have words.
We speak not because we absolutely have to, but because we need to. An average person can go quite a long time without communicating with anyone through writing, but not having someone to talk to can drive him insane. In 'Castaway', Tom Hanks stars as a FedEx delivery man stranded on an island. Among his delivery consignment he finds a football which he turns into a