[augustuspolius]

The phrasing they use is a bit confusing. "Speech" is not a clear quality description, so it's odd to compare speech to a CD quality recording (presumably 44.1 kHz). Speech can also be sampled at CD quality. If they meant to emphasize the difference in frequency range or dynamic range - there were, perhaps, better ways to do that (e.g. "telephone conversation" vs "symphonic orchestra recording").

[bscphil]

My best guess is that all they meant by "CD quality" was that it was targeting full band stereo replication, rather than narrow band as is typically used for speech. Not that it could achieve transparent compression at any particular bitrate.

The tiny music clip in the sample, encoded at 6 kbps, is obviously not any kind of evidence for "CD quality" one way or the other. (The clip itself, if you download it from the page, is re-encoded with 64 kbps AAC.) No way to know how it would stack up against 96 kbps Opus on a stack of CDs with blind testing, I don't think.