Answer :
Answer: Inattentional deafness.
Explanation: Inattentional deafness is the situation that is caused when the people tend to fail in hearing the audible sounds in the surrounding due to the circumstances of workload. The attention towards any event happening in the surrounding goes unnoticed by them in such cases.
The situation mentioned in the question states about the inattentional deafness of people because they were talking on the cell phone and thus are not able to notice the gorilla-suited man and the loud singing car.