How to establish transfer function of a speaker? I'm working on a signal processing project about vocal system, and I'm trying to use controlling theories to solve the problem. 

I need to get the transfer function, $H(s)$, of a speaker, from electrical signal to voice. But it seems that I have to use a microphone to pick up the voice. Considering the microphone itself has a transfer function $G(s)$, I will finally get $G(s)H(s)$ rather than $H(s)$.

So, is there any method to get TF $H(s)$ from electrical signal to vocal signal?



Well I have another problem. I've seen someone else estimating TF $G(s)H(s)$ by experiment. The bode diagram looks so strange and complex that I think it will be difficult to get a mathematical description of the system. So what method is usually used in controller-design when the object has a complex freq. response?
You can use a spark gap to measure the impulse response of the microphone. Spark gaps discharge within a very short time interval, producing a very broad spectrum that is effectively constant in the audible range.

If you also make sure that reflections that reach the microphone are arriving much later compared to the duration of the impulse response, you can separate the room response very well from the microphone response. Repeated measurements improve the estimation.

With the microphone response known, you can solve for the speaker response. However, technically you still have the room response and directional dependence of the speaker and microphone that you might want to consider.