diff --git a/fft-decode.py b/fft-decode.py
new file mode 100644
index 0000000..465aa6c
--- /dev/null
+++ b/fft-decode.py
@@ -0,0 +1,33 @@
+import soundbox
+import numpy as np
+import scipy.signal as sig
+import sys
+
+if len(sys.argv) != 2:
+    print(f"""Utilisation: {sys.argv[0]} [source]
+
+Détermine les notes jouées dans le fichier [source] en utilisant
+la transformation de Fourier.""")
+    sys.exit(1)
+
+source_file = sys.argv[1]
+
+# Calcul du FFT
+signal = soundbox.load_signal(source_file)
+freq_scale = soundbox.samp_rate / len(signal)
+
+vecs = np.fft.fft(signal)[:soundbox.samp_rate // 2]
+values = np.absolute(vecs) / np.max(np.absolute(vecs))
+freq = np.arange(len(values))
+
+# Calcul de la fenêtre des fréquences intéressantes
+high_enough = np.where(values >= 0.005)
+left = high_enough[0][0]
+right = high_enough[0][-1]
+
+freq = freq[left:right]
+values = values[left:right]
+
+# Recherche des pics
+peaks, _ = sig.find_peaks(values, height=0.1, distance=10 / freq_scale)
+print(list(map(soundbox.freq_note, freq[peaks] * freq_scale)))
diff --git a/fft-graph.py b/fft-graph.py
index 170bf64..360b20c 100644
--- a/fft-graph.py
+++ b/fft-graph.py
@@ -17,8 +17,19 @@ output_file = sys.argv[2]
 
 # Calcul du FFT
 signal = soundbox.load_signal(source_file)
+freq_scale = soundbox.samp_rate / len(signal)
+
 vecs = np.fft.fft(signal)[:soundbox.samp_rate // 2]
 values = np.absolute(vecs) / np.max(np.absolute(vecs))
+freq = np.arange(len(values))
+
+# Calcul de la fenêtre des fréquences intéressantes
+high_enough = np.where(values >= 0.005)
+left = high_enough[0][0]
+right = high_enough[0][-1]
+
+freq = freq[left:right]
+values = values[left:right]
 
 # Génération du graphe
 plt.style.use('ggplot')
@@ -30,15 +41,9 @@ plt.rcParams.update({
 
 fig, ax = plt.subplots()
 ax.tick_params(axis='both', which='major', labelsize=12)
-
-freq_filter = values >= 0.01
-freq = np.arange(len(values))
-ax.plot(freq[freq_filter], values[freq_filter])
+ax.plot(freq, values)
 
 # Configuration des axes
-freq_scale = soundbox.samp_rate / len(signal)
-
-
 def freq_format(value, pos):
     return f'{value * freq_scale:.0f} Hz'
 
diff --git a/soundbox.py b/soundbox.py
index 9e3fd5b..8930b84 100644
--- a/soundbox.py
+++ b/soundbox.py
@@ -113,20 +113,21 @@ def chord(instr, dur, freqs, value=1):
     return signal
 
 notes = {
-    'do': 0, 'si#': 0,
-    'do#': 1, 'reb': 1,
+    'si#': 0, 'do': 0,
+    'reb': 1, 'do#': 1,
     're': 2,
-    're#': 3, 'mib': 3,
-    'mi': 4, 'fab': 4,
-    'fa': 5, 'mi#': 5,
-    'fa#': 6, 'solb': 6,
+    'mib': 3, 're#': 3,
+    'fab': 4, 'mi': 4,
+    'mi#': 5, 'fa': 5,
+    'solb': 6, 'fa#': 6,
     'sol': 7,
-    'sol#': 8, 'lab': 8,
+    'lab': 8, 'sol#': 8,
     'la': 9,
-    'la#': 10, 'sib': 10,
-    'si': 11, 'dob': 11,
+    'sib': 10, 'la#': 10,
+    'dob': 11, 'si': 11,
 }
 
+rev_notes = dict(zip(*reversed(list(zip(*notes.items())))))
 
 def note_freq(note, octave):
     """
@@ -144,6 +145,24 @@ def note_freq(note, octave):
         * math.pow(2, (notes[note] - 9) / 12))
 
 
+def freq_note(freq):
+    """
+    Retrouve la note correspondant au mieux à une fréquence.
+
+    Paramètres:
+        note
+    """
+    log = math.log2(freq / note_freq('do', 3))
+    octave = math.floor(log) + 3
+    note = round(12 * log - 12 * math.floor(log))
+
+    if note == 12:
+        octave += 1
+        note = 0
+
+    return (rev_notes[note], octave)
+
+
 def note_freqs(notes):
     """Calcule la fréquence correspondant à un ensemble de notes."""
     return list(map(lambda info: note_freq(*info), notes))
diff --git a/sounds/synth.wav b/sounds/synth.wav
index e03bd48..42d29b3 100644
Binary files a/sounds/synth.wav and b/sounds/synth.wav differ