"Was one ears in" can be replaced by several synonyms that convey the same meaning. Some commonly used expressions are "was completely absorbed," "was totally engrossed," "was deeply immersed," and "was fully focused." All of these phrases imply a state of concentration, attention, and involvement in an activity or task. They suggest a state of being so focused on something that one is oblivious to anything else going on around them. In summary, when describing someone who is highly focused, we can use various synonyms for "was one ears in" to convey the same idea of concentration and absorption in the present moment.