measured a small project studio last week and the numbers are confusing me. the room is maybe 150 sq ft, pretty heavily treated with a mix of foam panels and some thicker broadband absorbers on the walls. ceiling has cloud panels too. owner built it himself over the last year and says it sounds way better than before treatment
ran rt60 measurements and the results dont match what i expected at all. low frequencies (125-250hz) are coming in around 0.3-0.35 seconds which makes sense for a small treated room. but then 500hz and 1khz are longer - more like 0.42-0.48 seconds. above 2khz it drops back down to around 0.25 seconds
i would have expected the opposite pattern since most absorption materials work better as frequency goes up. like shouldnt the highs be the shortest and the lows be the longest in a room with typical foam and fabric absorbers?
measured it twice on different days with source and mic in different positions each time and got basically the same pattern so i dont think its a measurement position issue. the decay curves look clean not like theres obvious flutter echo or modal stuff messing things up
the owner insists the room sounds good and honestly when i was in there it didnt sound obviously wrong or ringy. but the numbers are bothering me because i cant figure out what would cause this mid frequency bump in reverberation time
is there some acoustic principle im missing that would explain why a treated room would have longer RT60 in the mids? or is this a sign something weird is happening with the treatment itself?