journal: update README.md

1 files changed, 1 insertions, 1 deletions

diff --git a/README.md b/README.md
index 0ee22e9..7ed0bc5 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,7 @@ To use simply create a PSG49 object as follows:
 ```
 var emu8910 = new PSG49(YM_CLOCK_ZX, 50);
 ```
-Which sets the default clock speed and interrupt frequency. 
+Which sets the default clock speed and interrupt frequency (50 Hz). 
 
 This exposes a a PSG register file in the `emu8910.register` object:
 ```