diff --git a/amodem/config.py b/amodem/config.py
index e2b5c3d..b08bcab 100644
--- a/amodem/config.py
+++ b/amodem/config.py
@@ -14,8 +14,8 @@ class Configuration:
     latency = 0.1
 
     # sender config
-    silence_start = 0.25
-    silence_stop = 0.25
+    silence_start = 0.5
+    silence_stop = 0.5
 
     # receiver config
     skip_start = 0.1
diff --git a/amodem/tests/test_transfer.py b/amodem/tests/test_transfer.py
index 308053e..19d0647 100644
--- a/amodem/tests/test_transfer.py
+++ b/amodem/tests/test_transfer.py
@@ -49,13 +49,18 @@ def run(size, chan=None, df=0, success=True, cfg=None):
         assert rx_data == tx_data
 
 
-@pytest.fixture(params=[0, 1, 3, 10, 42, 123])
+@pytest.fixture(params=[0, 1, 3, 10, 16, 17, 42, 123])
 def small_size(request):
     return request.param
 
 
-def test_small(small_size):
-    run(small_size, chan=lambda x: x)
+@pytest.fixture(params=list(config.bitrates.values()))
+def all_configs(request):
+    return request.param
+
+
+def test_small(small_size, all_configs):
+    run(small_size, chan=lambda x: x, cfg=all_configs)
 
 
 def test_flip():