Yeah I agree. Sound range finding was in its infant stage in the war. It was very primitive. Hell it was still primitive in the 1970s.
Well, maybe in Australia ;-).
But seriously now, I beg to differ.
While first setups and devices used in WW I and in the 1920 can be seen as early (or rudimentary versions), the method was fully developed in WW II, according to sources from the German Bundeswehr and the Federal Archive (GER). German observation Abteilungen were quite successfull at pin-pointing Russian artillery units. In 1940, some artillery observation Bns were disbanded, in order to provide each Panzer-Division with a Panzer-observation Abteilung, containing a flash detection and a sound detection battery, a balloon platoon and a measuring section.
In Africa, observation battery 326 was attached to (Panzer-) Artillery Regiment 33, which was attached to the 15. Panzer-Division. The battery was formed by using the 3rd flash detection battery of observation Abteilung 10 and was employed throughout the African campaign, so the Germans used flash detection sections for counterbattery fire in Africa, definetly. I do not know whether the obs bty contained sound detection elements or not, right now. Panzer Artillery Abteilung 155, which was employed at Korps level at first, but then attached to the 21. Panzer-Division, might have had an obs bty as well, but the sources I checked just indicate 3 arty Bns and no obs detachment. Maybe the desert provides for a different "sound environment", as temperature, speed of sound (due to less humidity) and barometric pressure are different and have a strong impact on measurement capabilities. For instance, sonic speed will only kick in at 333 meters/second, if there's a base temperature of 3.5 degrees Celsius with a humidity of 78%, and 0 wind speed. Maybe the desert demanded too many calculations, I don't know
Whatsoever, in WW II, the Germans had fleshed out the technology, but the problem was the limited range (12-15 kilometers, depending on weather conditions and layout of the terrain). Only post-war devices and setups could increase the range to around 20 kilometers. But still, 12-15 kilometers matched or almost the range of light and medium arty pieces (4-18 kilometers). According to accounts I read, the Russians attributed some successful counterbattery missions to successful patrols of German recon planes, where in fact they had been triangulated by either sound detection or flash detection units, which made them move their artillery units in those sectors further away from the main line of battle and from aerial recon zones. I've also read accounts from veterans who served in fast units, reporting about destroyed Russian arty pieces residing in perimeters that had been plastered by German artillery, obviously, and where these Russian pieces could not have had direct contact with the fast units, as they had not fired a single shell in these instances.
German sound detection, flash detection, measuring and aerial recon units worked together closely.
In 1942, an observation Abteilung (then "light observation Abteilung, motorized" ) employed 637 troops, 55 cars (quite some armored cars, special versions of Sd.Kfz 251 and 250 with obs or detection equipment), 51 trucks (some amount with detection or radio equipment) and 26 Krads. After the return to the old structure (structure of 1940 , a full Abteilung with complete detection + measuring complements) in December 1943, the Abteilungen held even more troops and equipment.
Now, you could say that the Germans just believed that it was a useful technology or method, and that there was no empirical study or backup to prove that it worked (due to the fog of war and/or propaganda), similar to the issues science has with homeopathy. I doubt that the Germans would have put up such efforts to allocate such comparatively high amounts of troops to each Abteilung (24 + 1 Abteilungen in 1939 already) , which could have been used elsewhere very well, to form observation units, if the method was inadequate for locating enemy artillery units.