diff --git a/services/analysis-engine/tests/test_pitch_tracker.py b/services/analysis-engine/tests/test_pitch_tracker.py
index 84731c81..9e1c9970 100644
--- a/services/analysis-engine/tests/test_pitch_tracker.py
+++ b/services/analysis-engine/tests/test_pitch_tracker.py
@@ -207,3 +207,30 @@ def test_pitch_tracker_confidence_returns_low() -> None:
 
     result = tracker._compute_confidence(voiced_probs, voiced_flag, y)
     assert result == "low"
+
+
+def test_pitch_tracker_nan_f0() -> None:
+    """Test when pyin returns NaN for voiced f0 values."""
+    tracker = PitchTracker()
+    y = np.random.randn(22050)
+
+    with patch(
+        "librosa.pyin",
+        return_value=(np.array([np.nan, np.nan]), np.array([True, True]), np.array([1.0, 1.0])),
+    ):
+        result = tracker.track(y, sr=22050)
+        assert result["lowest_note"] is None
+        assert result["highest_note"] is None
+        assert result["confidence"] == "low"
+
+
+def test_pitch_tracker_low_avg_prob() -> None:
+    """Test when average voicing probability is less than 0.2."""
+    tracker = PitchTracker()
+    y = np.random.randn(22050)
+
+    with patch("librosa.pyin", return_value=(np.array([440.0]), np.array([True]), np.array([0.1]))):
+        result = tracker.track(y, sr=22050)
+        assert result["lowest_note"] is None
+        assert result["highest_note"] is None
+        assert result["confidence"] == "low"