diff --git a/tests/test_wave.py b/tests/test_wave.py
index aa08b4a..78f5bf3 100644
--- a/tests/test_wave.py
+++ b/tests/test_wave.py
@@ -1,12 +1,15 @@
 import warnings
 
+from hypothesis import given
+import hypothesis.strategies as hs
 import numpy as np
 from numpy.testing import assert_allclose
 import pytest
 from delayed_assert import expect, assert_expectations
 
+from corrscope.config import CorrError
 from corrscope.utils.scipy_wavfile import WavFileWarning
-from corrscope.wave import Wave
+from corrscope.wave import Wave, Flatten
 
 prefix = "tests/wav-formats/"
 wave_paths = [
@@ -38,9 +41,11 @@ def test_wave(wave_path):
         assert not [str(w) for w in warns]
 
 
+# Stereo tests
+
+
 def test_stereo_merge():
-    """ Ensure stereo channels are combined properly, when indexing by slices
-    *or* ints. """
+    """Test indexing Wave by slices *or* ints. Flatten using default SumAvg mode."""
 
     # Contains a full-scale sine wave in left channel, and silence in right.
     # λ=100, nsamp=2000
@@ -71,11 +76,47 @@ def test_stereo_merge():
     check_bound(wave[:])
 
 
+AllFlattens = hs.sampled_from(list(Flatten.__members__.values()))
+ValidFlattens = hs.sampled_from(Flatten.modes)
+
+
+@given(AllFlattens)
+def test_stereo_flatten_modes(flatten: Flatten):
+    """Ensures all Flatten modes are handled properly
+    for stereo and mono signals."""
+    wave = Wave(None, "tests/stereo in-phase.wav")
+
+    if flatten not in Flatten.modes:
+        with pytest.raises(CorrError):
+            wave.with_flatten(flatten)
+        return
+    else:
+        wave = wave.with_flatten(flatten)
+
+    nsamp = wave.nsamp
+    data = wave[:]
+
+    # wave.data == 2-D array of shape (nsamp, nchan)
+    if flatten == Flatten.Stereo:
+        assert data.shape == (nsamp, 2)
+    else:
+        assert data.shape == (nsamp,)
+        if flatten & Flatten.Diff:
+            np.testing.assert_equal(data, 0)
+        else:
+            assert flatten & Flatten.Sum
+            if flatten & Flatten.IsAvg:
+                pass  # FIXME
+
+
 def test_stereo_mmap():
     wave = Wave(None, prefix + "stereo-sine-left-2000.wav")
     assert isinstance(wave.data, np.memmap)
 
 
+# Miscellaneous tests
+
+
 def test_wave_subsampling():
     wave = Wave(None, "tests/sine440.wav")
     # period = 48000 / 440 = 109.(09)*