Increases in amplitude at resonant frequencies that are a function of the dimensions of a room.
"I just played the tape my Dad made in 1942 to my now 91year old Dad and 88 yr old Mom... It was a wonderful slice of family history to listen too. Backstory: My Dad was 21yrs old in November 1942. RAF pilot in-training --sent to Western Canada -- during a leave break he traveled to Seattle. David Beck's Teamsters (yes that David Beck) offered a ..."