In this video I compare the two most common ways of measuring your system's frequency response via RTA and discuss the potential issues when using these methods to EQ the response to match a house curve.
Cliff's:
This video is less about saying which one is best and more about educating people on the fact that the body in place method will result in a different response. Especially because so many try to use a "house curve" and don't consider that said curve(s) are not (likely) built with a body in place consideration (or for that matter, anything in the space at all). There is a measurable difference with a "body in place" vs "free field"-type when using the Moving Microphone Method for measuring your system response. This is especially notable for those who use a house curve to target a particular system response as, in every case I can think of, the house curved was derived from a "free space" condition (no body in the seated position). While I use various methods and do not believe one is necessarily better than the other, I am providing you with insight on why and how this can effect your end result.
In a standard home audio or home theater setting this isn't as big of a deal because the angle of the speakers are typically not severe enough where head shadowing plays a major role. Still, the measured difference between the two methods is about ±2dB from 200Hz to 2kHz. However, in car audio, this is more severe even higher in frequency because the passenger side speakers are often at a higher angle (as much as 40°-60° off-axis).