I’ve always been amazed with some AI’s that have shown up throughout the years, such as Google’s voice assistant, and NPC players in sports games. I was wondering where I would start with making my own, I’d imagine making a robot you can speak with would be interesting, kind of like cleverbot, any ideas?
To quote Mr. Ollivander: “You ask deep questions, Mr. Potter.”
It really depends on how sophisticated you want it to be. If you just want it to answer back with ‘whatever’, then you just write something that when it receives input just outputs something. If you want it to actually parse the input and attempt to respond intelligently…
… First, you scan through the words we hear and attempt to identify ones of importance. This means breaking the input down into its parts (Words) and then checking through a catalog of words to see if they’re there. Perhaps with little flags that say whether to ‘ignore this word’ or ‘that word’. Such as ‘is’ or ‘the’. Then it can attempt to come up with something worth saying on the given words and pick one.
Second, you can scan through for phrases, instead of just words. Which is even harder/slower.
Third, you attempt to identify the syntax of the language, and use that to construct the meaning of a sentence, which your bot can then respond to.
Fourth, you attempt to identify the semantics of the language, and use that to actually understand what a sentence means.
I would assume though, that you were more talking about step one. 
There are literary entire library of books on this topic. That would the correct place to start. Many of the books and online resources are at more less every level needed. ie for people just starting out or even experts.
A good place to start is with the chat bots out there. Quite simple ones trick many people very easily…
creating talking bot like siri in a game? forget it 
About simpler game AI, there is an interesting paper from monolith(?) about how they created the AI for the game F.E.A.R.
I should be clear when i say chatbots as well. I mean something that is in IRC channels.
There’re 4 main domains of AI. Searching, Reasoning, Planning, and Learning. If you see something/robot capables doing various thing, it must be combination of at least first three. Each domain serves different usage. Learning “Learning” will be harder but the usage is vary widely.