I have posted many questions to the Raspberry Pi stack exchange and not that many people view it. This means that I don't get an answer to any of my questions.
The small amount of views on questions is down to the Raspberry Pi being a fairly niche product. For a lot of the questions unless you happen to have the technical knowledge to fully understand what is going on, they simply aren't that interesting.
Also the number of very knowledgeable people on the site is very small, especially compared to the low rep users. All you have to do is look at the total reputation league table to see what I mean:
So it can take time for questions to get a really good answer, which is something that does tend to increase the views on a question. Not only because people on the site could be more likely to look at it, but the question might post higher up on a search engine query. In fact most of the traffic for the site is from search engines.
One reason a question might fail to get an answer is if it falls into a topic area like getting the Pi to connect to a network for example. Of course there could be any number of problems associated with that but those sort of questions can become really boring to answer after while.
Having looked at your questions that haven't got answers I think they share a common trend (with the exception of the real time Spectrum analyser with pyaudio); in that they are not necessarily specific enough. It's really important you show some evidence of research in your question otherwise it can become really challenging to answer.
For example your question about audio learning could be answered any number of ways. At the level the question is being asked at the moment it would take a full tutorial to solve your problem. That's a large time commitment that people simply aren't going to be willing to make.
Finally, to answer your question in the title, the site is very active, it's just a case that around the holiday season we seem to get an influx of questions and we seem to have a limited user group regularly posting answers.
I'm a regular user here, and try to look through new posts at least daily. There are many reasons I don't bother reading or answering posts:
There are a lot of niche interest groups using the RPi platform. In my case, I'm simply not interested in emulation or media center applications. I'm sure other folks are bored by the things I use mine for (networking and IoT projects).
If the subject of a post is vague, I won't usually bother reading the post. I have limited time, and want to help those folks I know I can help. If the subject isn't clear, I'm not going to spend much time figuring out if it's of interest or not.
If the post indicates minimal effort, or sounds like a "do my homework for me" exercise, I'm not inclined to put more effort into a response than the original poster. If a question can be trivially answered with a simple google search, it's not of much interest to me.
If the post is an obvious re-post, again indicating minimal or no effort on the poster's part, I may or may not bother responding, even if the topic is interesting.
The moderator emphasis here seems to be on trying to develop high-quality questions and answers with long-term value. The real value of SE sites is that long-term retention of answers. Sometimes, IMO, this emphasis is a bit too heavy, and discouraging to new posters as well as heavy-handed with experience posters. Fair enough, they're the mods, they make the rules. If a post is a repeat question, a terse "already been asked" response by a mod may kill the inclination of others to answer in more detail. It's not that the question hasn't been answered, but it's already been answered elsewhere. Unfortunately, not all mods indicate where.
The RPi ecosystem changes quickly. This works against the goals of the site noted in my previous point to some degree in that, by the time a "quality" answer has been assembled, some of the information may be obsolete by OS or hardware changes. A lot of the highest-rated answers here that I find aren't consistent with later OS releases (e.g. init versus systemd). What works for someone on one configuration may not work for someone else on a different configuration. Here again, if the post leaves out essential information such as the OS version being used, answering in a meaningful way is difficult and frustrating.