The UK’s radio ratings service, RAJAR, recently released the findings of its latest study of Internet-delivered audio services, including a healthy section on podcast consumption. Here are some of the principal findings, and a few thoughts on what they mean for podcast content producers:

1. The overall podcast audience continues to show significant growth: the overall UK figures rose from 6 million persons indicating they had ever downloaded a podcast in May 2008, to 7.2 million today. Also in that same period, the number of persons indicating that they listen to a podcast each week rose from 3.7 million to 4.1 million.

Two things strike me about these numbers–first, of course, podcast consumption continues to grow at a very healthy rate. More significant to me is the fact that 57% of the total podcast audience listens to a podcast each week. That, combined with the fact that the number of podcasts subscribed to increased from 3.6 to 4.4 is clear evidence that listening to podcasts is becoming more of a habit, and less of a novelty, for the majority of this ever-growing body.

If you are monetizing podcast content, habit is most definitely what you need. It is vital for content producers to encourage, promote and even reward regular, timely listening–again, the fact that podcasts can be consumed any old time is a benefit to the listener, but means that ‘campaigns’ can stretch for weeks–even months–and occur asynchronously. The more podcast producers can create and reinforce the habit of listening to a podcast, the more they can control variables and show demonstrable results for advertisers within a finite window of time. So listen whenever you want–but listen this week–and be creative about how you encourage your listeners to make the habit.

2. 33% of podcast listeners responded positively to the idea of podcasts without advertising that would have to be paid for. However, the same study showed that the number of podcast listeners who had actually paid for a podcast remained unchanged–3%.

I am sure that the 33% figure will get some headlines, and provide some comfort for podcasters trying to make a go of a paid subscription model. The proof, however, is in the Yorkshire pudding here–the real number hasn’t budged. That’s not to say that some paid subscription models won’t work–just that they won’t be common occurrences. Selling a podcast of a one-off event, for example, is a perfectly valid model. The last thing most of you should be doing, however, is putting up a barrier to growing your audience. Howard Stern’s reach is a fraction of what it used to be when you could hear his show for free on broadcast radio–and that’s Howard Stern.

3. 78% of podcast users listen to podcasts that are more than a week old.

This is, of course, the flip side of point #1–on the one hand, content producers need to continue to find ways to make content topical and “unmissable,” as I have written before in an analysis of Edison’s podcasting statistics. On the other, there is obviously a need for “evergreen” content (and detailed, easily-scannable show notes) to help listeners devise their own plans to “catch up” with your content, should they want to.