When writing a book on Audio Content Analysis and Music Information Retrieval, you know that the field is so small that you can’t expect high sales numbers. But nobody starts an academic book project for the money, anyway.
Still, I had no good idea of what sales numbers to expect from an academic book in a niche market. Searching for text book sales figures only gives a limited amount of vague results that do not necessarily compare to your field, such as the numbers in this list and the answers to this question. I found one resource giving specific sales numbers for academic books on Nietzsche.
Although I cannot really tell without comparison, it is my impression that the sales numbers for my book are reasonable but far from exciting. There is no way to say without a point of reference, so I decided to publish the current sales numbers for my book in the hope that others might find the sales figures for the first two years interesting and maybe publish comparable statistics. Without further ado, here they are:
A few notes: The 6-months cycle starts in September and in March, respectively. The book is available both as hardcover (blue) and as ebook (yellow); while the ebook is available at the IEEE, Wiley, and Google Books (among many other shops), it is neither available on amazon nor at Apple’s iTunes store.
There was a minor publishing hiccup in Aug 2012, so the book’s final release was in November 2012. Of the nearly 600 sold copies since then, about one quarter are ebook sales. I started to track amazon sales directly in 2013 with novelrank; this data I plotted in red. Note that the amazon data is only for hardcover sales but might include used books as well, as far as I understand.
Update 09/2015: here is the updated sales count.