My 4 month old is the most verbal baby I've ever seen. He has something to say in every situation. My husband and I tell him what things are, "That's a truck. It moves along the road.". My son clearly recognizes some words, like "hi", and I wonder if there is a way I could help him learn to understand and speak a little faster since he is so passionate about it?
Here are a few things that I've read in books and articles about encouraging your child to talk:
Show excitement when he tries to talk
Let him know that the noises he makes are important by paying attention and encouraging him when he coos. As he gets a bit older and his noises become more developed ("bababa" or "mamama" instead of just "aaaaah!"), then specifically encourage the more advanced consonant sounds.
Encourage him to copy you
This can be anything from making faces to peek-a-boo to actual sounds. If learns to enjoy imitating you, he will also begin imitating your speech.
Have "conversations" with him
When he's being vocal, coo at him and wait for him to respond, and then you coo back again. This way he can learn the ebb and flow of how conversations work.
The use of "motherese" http://www.education.com/reference/article/motherese-support-children-language-learning/ encourages children to attend to speech and provides an exaggerated model of the intonation and inflection of speech which helps her understanding of "talking".
When he begins to vocalize, listen intently with direct eye contact and exaggerated facial expressions. When he stops "talking", then respond with "motherese" stopping when he begins again. These exchanges teaches the concept of turn-taking which is necessary for "conversations".
Playing peek-a-boo, tickling games and simple action games all provide opportunities for turn-taking.
Imitating a child's sounds exactly encourages repetition of the sounds and is the beginning of imitation skills. A child's first words will likely be reduplications of syllables such as: mama, dada, baba, bubu or single syllable words beginning with the earliest developing consonants such as m, b, t, or d. These sounds naturally occur from muscle development from sucking.
Continue talking to your baby simply, clearly and often. He may not understand what you are saying, but will enjoy and learn from your conversations. Look and point at the things you talk about.
Read picture books to your baby. Describe what you are looking at and make any accompanying sounds that matches the pictures. Reading to a child is highly correlated with school readiness/success.
Repetition of rhymes and simple songs is also idea interactions that support language in children.
Follow your child's lead. Continue this vocal exchange for as long as he shows interest. When he indicates displeasure, recognize that he is ready to move on to another activity.
From about seven months babies start to use and understand hand and body gestures and natural signs. Express in words what your baby shows in signs and facial expressions.
Speak. Speak to others when he's in the room. Speak to him when you're alone with him. monologue about what you're doing, how you make soup, which sock belongs to which family member. Talk in the car about which way you're going, where, and why. Every chance you get, read books to him. Talk about the pictures. Everything else is detail.
Leave the TV off. He'd rather watch and listen to you anyway.
Keep is simple. All I can say, is children "accidentally learn things" so make it fun. Make animal noises, say the simple sounds that are similar to aahhhh like Maaaaaa Daaaaa Baaaa or even ta for thank-you. Read him books, he will most likely cackle himself, but point out the words, if he loves talking, you never know he might love words, and books and reading. Just don't push it, and enjoy your child while they are still young.
Beyond the short term answers given as requested) above, it is worth noting that language development is a long term processes. As noted in Slate and NY Times, ongoing conversation with your child adds greatly to their intellect. The Thirty Million Words Project exists specifically to address the issue of children's language development by encouraging greater interaction, especially in the poorer communities where the word gap is greatest.