My company (microsoft) participated in the first round of call for proposals for watermarks for music. For the longest time, content owners keep thinking this is a way of copy protection. It is not. All you can do is trace the content to the one with or without watermark. We (tech companies) adamantly fought the notion of using it for "copy control" and for the most part won. Proposals for example to only play music that has the official mark in them were thrown back at content owners and not implemented.
Back to watermark, it has multiple vectors:
1. How long of a mark needs to be inserted. 8 bits is easier than 64 bits. The more bits needed to be inserted, the more bits in music will need to change.
2. What is the shortest duration of music where the mark can be detected. Content owners want the shortest duration but from fidelity point of view, we want to hide the bits where they are least audible. If it takes 30 seconds, so be it. But this lengthens the forensic work to find the mark so there is always pressure to insert the mark/detect it in fewest seconds (e.g. 10).
3. How much CPU it takes to detect it. This is so that cheap embedded devices can find the mark and act on it. As is typically the case, simpler algorithm is less sophisticated in its ability to hide the mark.
4. Patent liability (i.e. risk of claims).
5. Cost of using the mark both in content and devices.
6. Resilience to damage due to data errors or transformation (e.g. encoding into MP3). For this reason, the mark data is hugely replicated. So what starts at 64 bits to be embedded, may turn out to be 64,000 bits you need to embed in the music.
All of these factors come into play before a label chooses a mark to embed. When at Microsoft, we proposed a sophisticated scheme that we thought did well in all of this but required a lot of CPU cycles. We lost out to a much simpler scheme that we thought was not sufficient at all.
I don't know what watermark technology is used these days. But the goal is always to reduce its audibility. To put it in context, it would be a lot easier to hear MP3 compression than a watermark. So I don't think most people will be bothered by it.