Andrew Culbert was increasingly having trouble hearing conversations in noisy restaurants. Then Culbert, a Boston corporate lawyer, noticed that he was missing key words during negotiations and depositions in a quiet conference room.

“It can lead to embarrassing situations sometimes,’’ Culbert said. “I can remember responding to people and they would look at me, somewhat in surprise, and that led me to realize I was not communicating with them about the subject matter.’’

Culbert’s difficulties began in his mid-50s, when hearing problems are quite common. Roughly 18 percent of Americans over the age of 45 report some hearing loss, and that number jumps to 30 percent in people over 65, according to the National Institute on Deafness and Other Communication Disorders.

As the number of older Americans rapidly increases, so too has research into the consequences of age-related hearing loss and new approaches to treating it. Certain exercises may help people distinguish sounds better, hearing aids are becoming more discreet and more useful in noisy rooms, and Boston scientists are working to regrow the tiny cells in the inner ear that are critical for hearing but die off as we age.

Age-related hearing loss tends to run in families. Repeated exposure to excessive noise and treatment with certain antibiotics can also damage the microscopic inner-ear cells, which resemble little hairs.

These “hair cells’’ work by picking up sound vibrations from fluid in the inner ear and transforming them into electrical signals that are relayed by other cells, known as spiral ganglion neurons, to the brain, which interprets them. After hair cells die, the spiral ganglion may also die.