fix: sound pause at wavegenerator (#2214)

Co-authored-by: Padmal <CloudyPadmal@users.noreply.github.com>

Author: kartikeysaran

app/src/main/java/io/pslab/activity/WaveGeneratorActivity.java

@@ -676,6 +676,9 @@ public boolean onCreateOptionsMenu(Menu menu) {
     public boolean onOptionsItemSelected(MenuItem item) {
         switch (item.getItemId()) {
             case android.R.id.home:
+                produceSoundTask.cancel(true);
+                produceSoundTask = null;
+                isPlayingSound = false;
                 finish();
                 break;
             case R.id.save_data:
@@ -1362,4 +1365,12 @@ protected void onCancelled() {
             }
         }
     }
+
+    @Override
+    public void onBackPressed() {
+        super.onBackPressed();
+        produceSoundTask.cancel(true);
+        produceSoundTask = null;
+        isPlayingSound = false;
+    }
 }