GREAT point.
That is WHY they are misinterpreting what they heard. Glad you get it now.
Burger was asleep at the time Stipp reports the first set of bangs. Even putting aside what those bangs were... Burger never heard them. Her testimony starts AFTER the first bangs.
Burger heard screams then the bangs (Stipp's second set of bangs). She said 2, then 2 or three, and now she says 4 for sure

She admits to READING and watching reports on the case, before making her Statements to police. She read that the case involved 4 gunshots. Not rocket science to figure out that she combined what she read with what she heard as her "testimony" evolved. Also burger is convinced that what she heard was gun shots because she knows the case involved gun shots. Not a stretch to see why she would assume loud bangs are gun shots. Who would guess "neighbors banging door with cricket bat"

And she read that 4 gunshots were involved. Natural human mental process to "fill in the gaps" and so convince oneself that the bangs heard were gunshots. Shame that she wasn't awake to hear the first set of noises. She can not compare the two sets of bangs. However Stipp heard both sets and he testified that they sounded the same.
Also I don't see its a stretch for somebody to ASSUME high pitched screams/wails are female... it's a natural sort of thing to assume. But men can produce high pitched voices too... especially at time of great stress and anguish.
I do NOT think Burger is "lying" as such... but she has embellished her story over time. And she did go beyond testifying to what she actually heard and venture into her interpretation...of what she heard in the context of what she has seen and read after the event.