Usage patterns
〈人〉の心が空虚になるfor someone's heart to feel empty or hollow
Even after succeeding, his heart felt empty.
空虚な〈言葉〉empty, hollow words lacking sincerity or meaning
His apology was nothing but empty words.
〈事〉の空虚さを感じるto feel the emptiness or pointlessness of something
I felt the emptiness of repeating the same routine every day.
〈場所〉が空虚だa place is empty or hollow (physically vacant)
The room with no one in it felt empty and hollow.