It’s a newer build, so concrete foundation walls and surrounding earth absorb and contain sound.Since there are two small children living in that home, did the home have a child proof keypad security lock on the front and back doors?
This is the kind of safety lock where small children cannot open the door from the inside without entering a pass code on the keypad.
North Fourth Street is a heavily traveled one way street that has heavy vehicular traffic all day long.
Folks are known to use both North Fourth Street and Summit Street as an alternative route to reach and leave Downtown Columbus when traffic on I-71 is backed up due to heavy traffic or accidents.
I also wonder if the house had heavy soundproofing to cut down on the traffic noise from North Fourth Street.
And if the house was soundproofed, it may explain gun shots weren't heard from the home.
Also, if only a few shots occur close together, the noise is brief and lacks a recognizable pattern. Easy for anyone who hears it to dismiss it as a single bang, or a firework rather than something sinister. If woke up to a noise at that time it would be confusing and like “wtf” - I would only think it’s a gunshot if I heard more shots afterwards.
The killer probably killed them both quite fast, in succession.