Speech Recognition Project - HMM I am looking for advice on a project I am thinking about completing (for experience etc..)

My project is triggering a set of traffic lights (simulation) using Speech recognition. In theory, I want to use a HMM (Hidden Markov model) to determine whether someone wants to cross the road or not, this can be determined by someone saying "Yes" and then if there is white-noise, or, the Phones "Yes" is not present it can infer that no-one wants to cross and therefore there is no need to trigger the lights.

I'm looking for advice in whether this can be done using an HMM? I have some experience in both of these I just need to know whether it would be a good idea to use an HMM / Viberti algorithm

I hope someone can help me,

Thanks :)
I learnt to use HTK based on this very basic tutorial

http://www.info2.uqam.ca/~boukadoum_m/DIC9315/Notes/Markov/HTK_basic_tutorial.pdf

It details how to make a yes/no recogniser. It should get you off to a good start at least.  There is also some HTK code on the main HTK site that allows you to perform real time speech recognition.

To improve robustness, you might also consider training the recogniser on speech tokens that are mixed with the kind of noises that you'd expect to hear around your receiver. You could place a recording device near to the traffic light and record a day's worth of background material, then randomly select samples windows to add to your speech corpus at various levels.