Very interesting article re: Digital Watermarking

I understand why there is a need for watermarking, just don't know why they felt the need to run it directly in the vocal ranges, it could have gone anywhere in the audio band since they have to use software to detect it consistently. A pattern at 18khz beneath the audio track would have been just as effective, but would have never been heard by the majority of listeners. In fast moving music, it isn't noticeable, but in piano or female vocals, it comes across as a distortion, that can be heard more often.

I guess with most popular music being recorded within the new levels of the "loudness wars," the pattern is way below recording levels. Soft acoustic music can suffer.