What is the difference between NB and WB entries in mixer_gains.xml? LineageOS for my phone has these sections with entries in the mixer_gains.xml file:

&lt;path name="gain-incall_nb-handset-mic"&gt;
&lt;path name="gain-incall_nb-handset-mic"&gt;
&lt;path name="gain-incall_nb-speaker-mic"&gt;
&lt;path name="gain-incall_nb-speaker-mic"&gt;
&lt;path name="gain-incall_nb-dex-speaker-mic"&gt;
&lt;path name="gain-incall_nb-dex-speaker-mic"&gt;
&lt;path name="gain-incall_wb-handset-mic"&gt;
&lt;path name="gain-incall_wb-handset-mic"&gt;
&lt;path name="gain-incall_wb-speaker-mic"&gt;
&lt;path name="gain-incall_wb-speaker-mic"&gt;
&lt;path name="gain-incall_wb-dex-speaker-mic"&gt;
&lt;path name="gain-incall_wb-dex-speaker-mic"&gt;


But I can't find what NB and WB stand for, or their difference, which makes it hard to know which to alter.

(I'm guessing they could stand for "no &lt;something>" vs. "with &lt;something>" but that doesn't help much)
The abbreviations here stand for narrowband (nb) and wideband (wb).

You can see the list of supported media formats, including the supports audio codecs here:
https://developer.android.com/guide/topics/media/media-formats

For example, the quite common AMR-NB codec.