diff --git a/GB_apu_set_sample_callback.md b/GB_apu_set_sample_callback.md
index 9a50c1f..3e00d80 100644
--- a/GB_apu_set_sample_callback.md
+++ b/GB_apu_set_sample_callback.md
@@ -4,14 +4,23 @@
 typedef void (*GB_sample_callback_t)(GB_gameboy_t *gb, GB_sample_t *sample);
 ```
 
-<tt>void GB_apu_set_sample_callback([[GB_gameboy_t]] *gb, [[GB_sample_callback_t]] callback);</tt>
+<tt>void GB_apu_set_sample_callback([[GB_gameboy_t]] *gb, GB_sample_callback_t callback);</tt>
 
 In `apu.h`
 
 ## Description
 
-TBD
+This function sets a callback that's whenever the emulator instance has a rendered sample ready. The rate in which the callback is called is controlled by the [[sample rate|GB_set_sample rate]].
 
 ## Thread Safety
 
 `GB_apu_set_sample_callback` is thread-safe and can be called from any thread and context.
+
+## Notes
+
+The callback isn't called when the sample rate is set to 0.
+
+## See Also
+
+* [[GB_sample_t]]
+* [[GB_set_sample_rate]]
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