diff --git a/tests/conftest.py b/tests/conftest.py
index 44f921f..047ebe2 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -11,6 +11,22 @@
 from qwerty_synth import config
 
 
+def is_portaudio_available():
+    """Check if PortAudio library is available."""
+    try:
+        import sounddevice
+        return True
+    except OSError:
+        return False
+
+
+# Create a pytest marker for tests requiring PortAudio
+requires_portaudio = pytest.mark.skipif(
+    not is_portaudio_available(),
+    reason="PortAudio library not found (install portaudio19-dev system package)"
+)
+
+
 @pytest.fixture(autouse=True)
 def reset_config():
     """Reset configuration to default values before each test."""
@@ -157,6 +173,8 @@ def noise():
 @pytest.fixture
 def mock_oscillator():
     """Create a mock oscillator for testing."""
+    if not is_portaudio_available():
+        pytest.skip("PortAudio library not found")
     from qwerty_synth.synth import Oscillator
     return Oscillator(440.0, 'sine')
 
diff --git a/tests/test_arpeggiator.py b/tests/test_arpeggiator.py
index 803362f..44d647d 100644
--- a/tests/test_arpeggiator.py
+++ b/tests/test_arpeggiator.py
@@ -1,6 +1,13 @@
 """Tests for arpeggiator functionality."""
 
 import pytest
+
+# Skip entire module if sounddevice/PortAudio is not available
+try:
+    import sounddevice
+except OSError:
+    pytest.skip("PortAudio library not found", allow_module_level=True)
+
 from unittest.mock import patch
 from PyQt5.QtWidgets import QApplication
 
diff --git a/tests/test_controller.py b/tests/test_controller.py
index a964856..9b63b72 100644
--- a/tests/test_controller.py
+++ b/tests/test_controller.py
@@ -1,5 +1,13 @@
 """Comprehensive unit tests for the controller functionality."""
 
+import pytest
+
+# Skip entire module if sounddevice/PortAudio is not available
+try:
+    import sounddevice
+except OSError:
+    pytest.skip("PortAudio library not found", allow_module_level=True)
+
 import time
 from unittest.mock import patch, MagicMock
 import threading
diff --git a/tests/test_input.py b/tests/test_input.py
index 8da2fe3..0a6e927 100644
--- a/tests/test_input.py
+++ b/tests/test_input.py
@@ -1,10 +1,16 @@
 """Integration tests covering keyboard events routed through the controller."""
 
+import pytest
+
+# Skip entire module if sounddevice/PortAudio is not available
+try:
+    import sounddevice
+except OSError:
+    pytest.skip("PortAudio library not found", allow_module_level=True)
+
 from types import SimpleNamespace
 from unittest.mock import Mock, patch, call
 
-import pytest
-
 from qwerty_synth import config, controller
 from qwerty_synth.keyboard_midi import MidiEvent
 
diff --git a/tests/test_keyboard_integration.py b/tests/test_keyboard_integration.py
index 441fb42..7a984b9 100644
--- a/tests/test_keyboard_integration.py
+++ b/tests/test_keyboard_integration.py
@@ -1,8 +1,15 @@
 """Integration tests covering keyboard translator to controller flows."""
 
+import pytest
+
+# Skip entire module if sounddevice/PortAudio is not available
+try:
+    import sounddevice
+except OSError:
+    pytest.skip("PortAudio library not found", allow_module_level=True)
+
 from unittest.mock import Mock
 
-import pytest
 from pynput.keyboard import Key, KeyCode
 
 from qwerty_synth import config, controller
diff --git a/tests/test_midi_integration.py b/tests/test_midi_integration.py
index 60b5089..2de8901 100644
--- a/tests/test_midi_integration.py
+++ b/tests/test_midi_integration.py
@@ -1,8 +1,15 @@
 """Integration test for MIDI controller → controller flow."""
 
-from unittest.mock import Mock, MagicMock, patch
 import pytest
 
+# Skip entire module if sounddevice/PortAudio is not available
+try:
+    import sounddevice
+except OSError:
+    pytest.skip("PortAudio library not found", allow_module_level=True)
+
+from unittest.mock import Mock, MagicMock, patch
+
 from qwerty_synth import config, controller
 from qwerty_synth.midi_input import MidiPortTranslator
 
diff --git a/tests/test_synth.py b/tests/test_synth.py
index 6b4096a..dfff78b 100644
--- a/tests/test_synth.py
+++ b/tests/test_synth.py
@@ -1,5 +1,13 @@
 """Comprehensive unit tests for the core synthesizer functionality."""
 
+import pytest
+
+# Skip entire module if sounddevice/PortAudio is not available
+try:
+    import sounddevice
+except OSError:
+    pytest.skip("PortAudio library not found", allow_module_level=True)
+
 import numpy as np
 from unittest.mock import patch, Mock
 import threading