What is the difference between Lavg and TWA?
Lavg is the average sound level over the run time of your sample. If you ran the meter for 30 minutes, Lavg is the average sound level over that 30-minute period. TWA always assumes an 8-hour run time. So if you ran the meter for 30 minutes, TWA would assume 7 hours 30 minutes of silence and give the 8 hour average.