The Raspbian image at the time of writing is the `May 2016` version, with the release date of `2016-05-10`. It does not include `libsoxr`, but it is available as a package via `apt-get`.

Alternatively, `libsoxr` is very easy to compile. Here are very brief instructions to download, compile and install it:

* Install `cmake`. This is used in the building of libsoxr:
```
sudo apt-get install cmake
```
* Download the `libsoxr source`:
```
git clone git://git.code.sf.net/p/soxr/code libsoxr
```
* `cd` into the `libsoxr` directory and start the build process:
```
cd libsoxr
./go
```
Be patient! This takes a long time on a Raspberry Pi -- it looks like it gets stuck around 40% or 50%, but it will finish if you let it.

Having compiled `libsoxr`, it must now must be installed:
```
cd Release
sudo make install
```
Finally, for Shairport Sync to be able to locate `libsoxr-dev` during compilation, you need to tell `ld` to catalogue it:
```
sudo ldconfig -v
```
That's it. Now you can select the `--with-soxr` option when you're building Shairport Sync.