diff --git a/src/test/java/device/usbPlayer/UsbPlayerTest.java b/src/test/java/device/usbPlayer/UsbPlayerTest.java
index 1bc8d55..d3805a2 100644
--- a/src/test/java/device/usbPlayer/UsbPlayerTest.java
+++ b/src/test/java/device/usbPlayer/UsbPlayerTest.java
@@ -68,16 +68,21 @@ class UsbPlayerTest {
         up22.louder();
         //third case
         UsbPlayer up3 = new UsbPlayer(USBDrive);
-        up3.setLautstaerke(100);
+        up3.setLautstaerke(10);
         up3.mute();
         up3.louder();
-
-
+        //forth case
+        UsbPlayer up4 = new UsbPlayer(USBDrive);
+        up4.setLautstaerke(10);
+        up4.mute();
+        up4.unmute();
+        up4.louder();
 
         return Stream.of(
                 Arguments.of("Volume is : 1 ", up11, 1),
                 Arguments.of("Volume is : 100 ", up22, 100),
-                Arguments.of("Volume is muted,no change can be made ", up3, 0)
+                Arguments.of("Volume is muted,no change can be made ", up3, 0),
+                Arguments.of("Volume is muted,a change has been made ", up4, 11)
         );
     }