The old man represents the depths of despair and depression a person could experience in a lifetime. His deafness makes him physically isolated from the rest of the world, as he is deprived of the pleasure of human conversation. He can still feel the difference between a noisy business day and a quiet night when only the wind rustles the leaves.
Deafness is a multilayered symbol in Hemingway’s short story. It has a literal, an intermediary, and a hidden meaning.
First, the reader feels sorry for the older man because of his disability. If it were not for his deafness, we would not understand why he was so depressed. But we are used to be sympathetic to people with disabilities. It is what Hemingway wanted us to do.
Second, the man’s deafness is a wall between him and other people. He cannot cry on the shoulder of a drinking companion, nor can he support a small talk with a waiter or his niece. The man is walled-up inside his own head. That is why alcohol and nighttime are his only friends.
Third, there is also a symbolic aspect of his deafness. As we can see from Hemingway’s version of The Lord’s Prayer, the author shows religious disillusionment. No religion can withstand the test of nothingness. But while the older waiter can still pray, even without faith, the man is deaf to Christianity and its moral support. He sits in this artificial world, in the shadow cast from electric light. He dumbs his feelings with brandy and cannot hear a word of support from anyone, be it a person or a god.