Right now, your child is still primarily cooing or babbling, which is one of the ways infants learn to use the parts of their body necessary for speech. Cooing and babbling are good signs, and should be encouraged!
At 9 months, your son could start saying a recognizable word any day, or it could even be another 9 months away. Each child is different, and what age they start speaking within the 9 to 14 month range is generally not an indicator of advanced or delayed development, and 18 months isn't unusual.
Right now, continue speaking around and to your child, and encourage them to continue their babbling. Children initially learn language through reception, which means they start understanding what's being said to them. Only later (or possibly very soon for you) do they begin expressive language, where they start using words they know. As you continue talking to your baby, they'll start understanding more words. Eventually, they'll want to say them.
You may also want to try adjusting the manner in which you speak around your child. Specifically, it's worth investigating and trying Infant Directed Speech (IDS).
IDS, sometimes called baby talk, has a few specific characteristics, which do not include using made-up "baby" words, such as "wub wub" or "goochy goochy goo".
- The pitch of the voice is higher
- Vowels are stretched out
- Pauses between words are slightly exaggerated
The theory is that using IDS in such a way makes it easy for an infant to discern when words start and stop, and thus separate one word from another.
While this is an exciting time, it will be important for you to properly manage your expectations, and not get frustrated if your child's first word is months away. Also, you won't really be able to influence which word is the first one she chooses to or is capable of saying. Continue using a variety of words, without necessarily focusing on repeating a single word. While he may not yet be speaking, his is still learning words (receptive language), and keeping up the variety of words not only exposes him to a greater vocabulary, but a greater variety of phonemes.
That said, my wife and I made sure to refer to one another by name whenever speaking around our son. Instead of, "Hi", it'd be "Hi, Mama." Instead of, "What's for dinner?" it'd be "What's for dinner, Papa?" I can't say it helped him say "Mama" or "Papa" any sooner, but I would say our conscious (over)use of those words helped him more quickly learn to understand them, and to associate them with the correct parent.
Here are some web references for you. They don't contain the scientific studies, but their information is consistent with the related research.