Area under the peak, clean peak

Hi there folks

I am toying with ideas about how to best define the cleanness of a peak. I have some frequency spectra that is very different. My first lots gives nice clear cut peaks whilst my other lots gives peaks at the same frequency but in all it much more messy. I have been considering a way to quantify what I'm seeing and thought to determine the area under the predominant peak and then work it out as a ratio of the background but I'm not sure how to go about this is MATLAB. Are there any predefined functions to make my job easier. I can picture having to fit a curve perhaps in matlab to my peak somehow but I have no idea how to work out the area of the background. Any ideas would be greatly appreciated