This question can only be answered by empirical testing using an actual human ear as a test basis --- no amount of audio equipment, however sophisticated, can properly measure the totality of the effect. I believe the proper test protocol should be along these lines --- after an examination to determine that the subject's (your, or a willing alternative volunteer's) audio acuity is identical in each ear (assuming you are not an Appalachian, an alien, or for some other reason, have more, or fewer ears) should be blindfolded ( so as to have no anticipatory reaction), seated comfortably in a chair, while an assistant discharges one of each example firearm, equidistant from each ear, with the cylinder gap and ejection port in approximately equal positions, to account for the variances in the direction of the escaping gasses and concomitant sound pressure. This means that an equitable test would involve the semi-auto being fired adjacent to the left ear, if fired from behind the subject, the revolver, next to the right. (Suitable precautions against powder burns and hot case contact ought to be provided...)
Lacking sophisticated measuring equipment, as most of us do, I'm pretty sure that you can use any auditory baseline standard, such as the Beatles Abbey Road, or the Stone's Sticky Fingers, while played at RIAA standards for high volumes, to determine which ear is first capable of recognizing frequencies above or below those characteristic of tinnitus.
I'm happy to be of whatever help you may have found this to be, and hopeful of hearing, in a manner of speaking, of your results.
