I remember coming to the understanding that a square wave, which is a collection of fundamental and (odd) harmonics frequencies, could then be used to give an indication of frequency response.

Turns out, adding in the frequency domain looks like multiplication in the time domain, so we actually want to multiply the two signals together. In general, a good math model for a sine wave is: ...

This process involved the multiplication of sine wave forms. Lab view contains a provision to perform this action ... Effects of Adjusting the Low Cut off Frequency: With a higher low cut off ...