When digital radio technology was introduced, it was meant to make radio better for everyone. The best digital radio can offer includes higher quality sound, more programming from a single frequency and data services. The adoption of the technology, at least in the United States, has been slow going.

According to the Federal Communications Commission (FCC), which regulates all radio broadcasts over AM and FM frequencies, the AM digital broadcasts on HD radio sound like FM radio, while FM digital broadcasts have CD-like quality.

Digital FM radio, in particular, is a popular medium for multicasting, or substations. For example, if you tune in to FM 99.5, you can hear the analog broadcast on any radio tuner. On a tuner that lets you pick up digital broadcasting, you can listen to the digital broadcast, which has improved sound quality. Also, if you tune to FM 99.5 HD2 or HD3, you might be able to pick up different music broadcasts, repeats of programs and more.

Radio tuners that can pick up digital broadcasts also have screens that display text, generally. The digital broadcasts include data that shows up on those screens, so listeners can also see what they're listening to, whether it's a program name, a radio station's call letters, or a song title and artist's name.

However, the latest statistics show that HD radio hasn't picked up steam as quickly as, say, digital television. The Pew Research Center showed that since the start of the digital radio switch, adoption of the new technology was rapidly growing for a few years, and was at its peak in 2006. After that though, the number of stations converting to HD sharply declined and continues to do so. As far as consumers go, only about 6 percent of listeners of public radio have access to HD radios.

Unlike the digital TV conversion, HD radio hasn't been mandated by the U.S. government, nor is there as much marketing directed at consumers about the additional HD channels for digital radio stations. Analog radio is still being broadcast, so there hasn't been a big enough push on consumers to replace old radios in their homes, pockets or vehicles. Additionally, traditional, or terrestrial, radio and HD radio have many competitors, such as podcasting, satellite radio and internet radio.

There still may be a future for HD radio, but for consumers, devices are few and far between. You can find a handful of portable digital radios, and digital pocket radios are practically non-existent.

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