It’s tiny, it’s sleek, and consumers are raving about its great sound. The latest iPod model? No, it’s a new type of hearing aid. Made with the latest in digital technology and nearly invisible when worn, the device is intended for people with high-frequency hearing loss. It has been on the market for less than a year, but one leading company says sales of the new hearing aid have been four times higher than expected.

Following the bite-size music players and ever-shrinking cell phones facilitated by the digital revolution that long ago attracted the public eye – and ear – hearing aid companies with much less fanfare have been using similar technology to fashion hearing devices that allow for increasing precision and comfort.

The advances, doctors say, have allowed more and more people to seek help for forms of hearing loss where previously available treatments offered little benefit.

“It’s a brand-new segment of the population that can be helped,” an audiologist on the Upper West Side, Dominick Servedio, said. The new devices can best help people with only mild to moderate high-frequency hearing loss, which accounts for about 20% of hearing impairment cases, Dr. Servedio said.

For people who suffer from high-frequency hearing loss, the traditional style of device that is inserted into the ear had been ineffective because by blocking the ear canal, it compromised a patient’s hearing at lower pitches. “A lot of people were really annoyed by hearing their own voices echoing in their ear,” the director of otology at Beth Israel Medical Center, Ronald Hoffman, said.

In the last two years, hearing aid makers have introduced and improved upon a device that fits in back of the ear, rather than inside. This new “open-fit” model can enhance high-pitch sounds, such as a child’s voice or a telephone ring, without disturbing a person’s unimpaired hearing.

“It’s much easier to listen,” the director of Beth Israel’s Hearing and Learning Center, Jane Madell, said. Dr. Madell, who treats children with hearing loss, has been wearing “open-fit” hearing aids made by GN ReSound since April and said they have made an enormous difference.

Although the “open-fit” design has been available for about two years, the early models were expensive and did not have as many features as conventional hearing aids. Last April, Unitron Hearing introduced the Conversa. NT, a fully functional hearing aid with added features available in both “open-fit” and conventional designs.

Sales of the Conversa. NT have been four times higher than Unitron’s expectations, the company’s director of audiology, Donald Hayes, said. “We way underestimated the sales on these things,” Dr. Hayes said. “We couldn’t stock them for the first couple of months.”

Several companies now offer the “open-fit” design, which typically features a small device placed in back of the ear connected to a virtually invisible, razor-thin tube leading into the ear canal. Controls on top of the ear device allow users to switch among different settings appropriate to their environment. One setting better isolates sound in a crowded restaurant, for example, while another is better for watching television.

Doctors also say the less intrusive – and less visible – designs have made converts of many people who had long put off wearing hearing aids. “People who would otherwise have rejected hearing aids are now willing to wear them younger,” Dr. Hayes said, citing a decrease by three to five years in the average age of first-time hearing aid users, to between 65 and 67.

To Dr. Madell, focusing on the improved look of modern hearing aids only exacerbates the negative image associated with hearing loss. “Hearing loss is not something to be embarrassed about,” she said. “It’s not a sign of mental incompetence to have a hearing loss. It’s not a sign of being a crazy person. It’s a hearing loss.”