But it’s not the technology or the price that will be decisive in selling these products to baby boomers, said Daniel Pink, author of “To Sell Is Human.” “We all know that boomers have drunk from the fountain of youth, and will never need or use a product that their parents use, like a cane or hearing aid,” he said.

If in-ear amplifiers don’t have the look and feel of a hearing aid, boomers and others might actually consider wearing them, he said: “You fuse the technology of extra support and utility with ways to make the devices acceptable.”

One company in the market, Sound World Solutions, will introduce a second version of its CS10 Bluetooth-enabled sound amplifier and app in April, said Kevin Daniels, director of sales and marketing. The new model, called the CS50 and costing $399, allows wearers to program and control the in-ear amplifier via free apps for Android and iPhone smartphones. Both left- and right-ear versions are available.

The product looks much like a Bluetooth headset, and not by accident. “We designed it to look like a Bluetooth device, and not to look like a hearing aid,” Mr. Daniels said. The model lets users set their own auditory profiles, or use one of the preset levels, including one for the clamor of busy restaurants.

Users can also stream music or audiobooks and make mobile phone calls, Mr. Daniels said. “Whatever you pair this device to,” he said, “it will play the audio in the device.” It uses a low-energy form of Bluetooth that lasts up to 15 hours on a single charge, he said.

Another app-paired amplifier, created by Soundhawk, is due later this year, said Michael Kisch, the company’s president and chief executive. Soundhawk has raised $5.7 million from True Ventures and other investors. The product, which will cost several hundred dollars, won’t be called an earpiece. “That sounds like a hairpiece,” Mr. Kisch said. Instead, the company will have a new vocabulary for its product, he said, disclosing only that it would be “much more compelling to consumers.”