не обращал

didn't pay attention

→ не
phrase Rare #24,387
didn't pay attention Used with на кого or на что and the genitive of внимание: не обращал внимания на него means “didn't pay attention to him.” The form обращал is masculine singular past tense.
RU: Я не обращал внимания на шум.
EN: I didn't pay attention to the noise.

Том не обращал на меня внимания.

Tom didn't pay attention to me.

Я просто не обращал внимания.

I just wasn't paying attention.

А я не обращал на него внимания.

But I didn't pay any attention to him.

— Жан Де Флоретт (1986)

На вашем месте я бы не обращал на это внимания.

If I were you, I wouldn’t pay any attention to it.

Ни один из мальчиков не обращал на Мэри внимания.

None of the boys paid any attention to Mary.

Просто раньше не обращал внимание.

I just hadn't noticed before.

— Бешеные псы (1992)

Никто не обращал на это внимания.

Nobody paid any attention to it.