As I understand it, each type of wave has a specific frequency characteristic. Based on this, bandpass filters can be designed to filter the specific wave out. This can be done using the Filter Designer app. Select the appropriate parameter and export the coefficient of the filters into MATLAB workspace.
Using these coefficients, you can use the filter function with the coefficients and the input signal to generate the filtered output, which would be the specific wave segment you are looking for.
Hope this helps!