On the eve of this month's NAB Convention, I find myself reminiscing that as recent as the mid 1980s, "broadcast quality" was a common qualifying phrase associated with the highest caliber audio production equipment. This was in the days of vinyl, cassette tapes and radio as the primary music media for consumers. The 50 Hz - 15 kHz frequency response of FM radio, with the (rarely realized) potential for some 70 dB of dynamic range, was not a compromise to the general public, and equipment capable of meeting those standards were acceptable to professionals.
The compact disc brought a major change in perception. Frequency response was extended to the commonly held limits of human hearing. Dynamic range had a potential of 96 dB. There was some initial resistance to the digital transition, caused in part by the lack of proper implementation of dither, by ignorance of the importance of precision clocking and jitter avoidance and by the often poor implementation of analog antialiasing filters. Despite the obstacles, consumers embraced the CD for its potential for clarity, the consistency of performance, improved resistance to wear, and the smaller form factor. "Broadcast quality" was supplanted by "CD quality," as the new buzz phrase used to loosely quantify top-flight performance.
Perception of broadcast quality has enjoyed resurgence of late, again born on a digital revolution, this time in television. Dynamic range, frequency response, and nonmatrixed multichannel sound are all improved and are obvious to the average consumer, even if the source is lossy compressed.
The phrase "broadcast quality," though, isn't likely to enjoy rebirth as the pinnacle of technical excellence, even if television production is employing technology that performs at a very high level. And, aside from improvements in the capabilities of radio broadcast gear in general, benefiting from the same gains in technology as the rest of audio production, little has actually been done to improve the overall quality of radio broadcasts. The limitations are defined by the medium and by a marketplace embracing hyper-compression. Digital radio may yet become the standard, but in the current "HD" implementations simultaneously broadcast with, and band-limited by, analog signals, its potential can never be realized. Lossy compression is used to a degree that would be rejected by most iPod users.
"CD quality" is also no longer a definitive statement of quality, the phrase having been misused and abused, and the standards supplanted by new professional standards. There's not a single commonly accepted professional standard, though a consensus could probably be established for minimum criteria both analog and digital. While the language has changed, even minimal "professional" performance is commonly giant steps ahead of that of a few decades ago, while cost of production has come down. That's progress, by any nomenclature.