diff --git a/papers/doc/7-systems/soundunit.md b/papers/doc/7-systems/soundunit.md
index 89e34655..8c3863b9 100644
--- a/papers/doc/7-systems/soundunit.md
+++ b/papers/doc/7-systems/soundunit.md
@@ -12,7 +12,7 @@ This is a fantasy sound chip, used in the specs2 fantasy computer designed by ti
   - 5: periodic noise
   - 6: XOR sine
   - 7: XOR triangle
-- `12xx`: set waveform (0 to 7F)
+- `12xx`: set pulse width (0 to 7F)
 - `13xx`: set resonance of filter (0 to FF)
   - despite what the internal effects list says (0 to F), you can use a resonance value from 0 to FF (255)
 - `14xx`: set filter mode and ringmod