Maybe you can’t read.
~Grin~
Maybe I can, and maybe that's why you don't wish to answer the question: What time do you believe the sounds of the ambulance arrival happened?
Another way of asking this question would be: What time do you believe Mr. Oswald heard the sounds of the ambulance arrival?
Another way of asking this question would be: What time do you believe Mr. Oswald was spotted by Mr. Rowland near the SW window of the sixth floor?
Take your pick, Mr. Collins!