add I/O tests on mono sound and fix typos

stimuli/audio/_base.py

@@ -75,7 +75,7 @@ def __init__(
         # the arguments sample_rate, device, clock, and **kwargs are checked in
         # the backend initialization.
         self._backend_kwargs = kwargs
-        self._backend = BACKENDS[backend](sample_rate, device, clock=clock)
+        self._backend = BACKENDS[backend](device, sample_rate, clock=clock)
         self._set_times()
         self._set_signal()
 

stimuli/audio/sound.py

@@ -2,6 +2,7 @@
 
 from typing import TYPE_CHECKING
 
+import numpy as np
 from scipy.io import wavfile
 
 from ..time import Clock
@@ -46,23 +47,22 @@ def __init__(
         sample_rate, original_signal = wavfile.read(self._fname)
         _check_signal(original_signal)
         volume = _extract_volume(original_signal)
-        signal = _ensure_signal(original_signal)
-        duration = signal.shape[0] / sample_rate
+        self._original_signal = _ensure_signal(original_signal)
+        duration = self._original_signal.shape[0] / sample_rate
         super().__init__(
             volume,
             duration,
             sample_rate,
             device,
-            signal.shape[1] if signal.ndim == 2 else 1,
+            self._original_signal.shape[1] if self._original_signal.ndim == 2 else 1,
             backend=backend,
             clock=clock,
             **kwargs,
         )
 
     @copy_doc(BaseSound._set_signal)
     def _set_signal(self) -> None:
-        signal = self._original_signal * self._volume / 100
-        super()._set_signal(signal)
+        super()._set_signal(self._original_signal)
 
     @BaseSound.duration.setter
     def duration(self, duration: float):  # noqa: D102

stimuli/audio/tests/test_sound.py

@@ -0,0 +1,17 @@
+from numpy.testing import assert_allclose
+
+from stimuli.audio import Noise, Sound
+
+
+def test_sound_io_mono(tmp_path):
+    """Test sound saving/loading."""
+    sound = Noise("pink", volume=100, duration=0.5)
+    sound.save(tmp_path / "test.wav")
+    sound_loaded = Sound(tmp_path / "test.wav")
+    assert_allclose(sound.signal, sound_loaded.signal)
+
+    sound = Noise("pink", volume=50, duration=0.5)
+    sound.save(tmp_path / "test.wav", overwrite=True)
+    sound_loaded = Sound(tmp_path / "test.wav")
+    sound_loaded.volume = 50
+    assert_allclose(sound.signal, sound_loaded.signal)