diff --git a/lhotse/testing/dummies.py b/lhotse/testing/dummies.py
index 76b8f4fc7..aec6a7581 100644
--- a/lhotse/testing/dummies.py
+++ b/lhotse/testing/dummies.py
@@ -100,7 +100,7 @@ def dummy_audio_source(
         if len(channels) > 1:
             data = data.unsqueeze(0).expand(len(channels), -1).transpose(0, 1)
             # ensure each channel has different data for channel selection testing
-            mults = torch.tensor([1 / idx for idx in range(len(channels))])
+            mults = torch.tensor([1 / idx for idx in range(1, len(channels) + 1)])
             data = data * mults
         binary_data = BytesIO()
         soundfile.write(