diff --git a/src/test/java/device/usbPlayer/UsbPlayerTest.java b/src/test/java/device/usbPlayer/UsbPlayerTest.java
index d3805a2..d94b380 100644
--- a/src/test/java/device/usbPlayer/UsbPlayerTest.java
+++ b/src/test/java/device/usbPlayer/UsbPlayerTest.java
@@ -82,7 +82,7 @@ class UsbPlayerTest {
                 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,a change has been made ", up4, 11)
+                Arguments.of("Volume is unmuted,a change has been made ", up4, 11)
         );
     }
 
@@ -109,11 +109,18 @@ class UsbPlayerTest {
         up3.mute();
         up3.quieter();
 
+        //forth case
+        UsbPlayer up4 = new UsbPlayer(USBDrive);
+        up4.setLautstaerke(10);
+        up4.mute();
+        up4.unmute();
+        up4.quieter();
+
         return Stream.of(
                 Arguments.of("Volume must stay 0 ", up1, 0),
                 Arguments.of("Volume must be 9 ", up2, 9),
-                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 unmuted,a change has been made ", up4, 9)
         );
     }