diff --git a/doc/6-sample/README.md b/doc/6-sample/README.md
index efad91458..ba73e549f 100644
--- a/doc/6-sample/README.md
+++ b/doc/6-sample/README.md
@@ -151,8 +151,10 @@ in there, you can modify certain data pertaining to your sample, such as the:
 - **Signed/unsigned exchange**: reinterprets selection data as being of the opposite sign.
   - if a sample sounds fine elsewhere but is distorted on import, it may have been interpreted as signed when it should be unsigned, or vice versa; this will correct that.
 - **Apply filter**: filters the selection. pops up a dialog box:
-  - **From**: filter cutoff frequency at start of selection.
-  - **To**: filter cutoff frequency at end of selection.
+  - **Sweep (2 frequencies)**: if checked, the "Frequency" slider is replaced with "From" and "To" sliders, and the filter cutoff sweeps between the two.
+    - **Frequency**: filter cutoff frequency.
+    - **From**: filter cutoff frequency at start of selection.
+    - **To**: filter cutoff frequency at end of selection.
   - **Resonance**: emphasizes frequencies around filter cutoff.
   - **Power**: number of times resonance is applied.
   - **Low-pass**: amount to attenuate everything above cutoff.