diff --git a/index.html b/index.html
index 98ca757..5483ba8 100644
--- a/index.html
+++ b/index.html
@@ -99,6 +99,11 @@
       <div class="chart-container">
         <canvas id="spectrumChart"></canvas>
       </div>
+      <div class="legend">
+        <span class="legend-item"><span class="legend-swatch" style="background:#00bcd4"></span>Power Spectrum</span>
+        <span class="legend-item"><span class="legend-swatch legend-swatch-dashed" style="border-color:#ffc107"></span>Cutoff</span>
+        <span class="legend-item"><span class="legend-swatch legend-swatch-dashed" style="border-color:rgba(255,82,82,0.5)"></span>Noise Floor</span>
+      </div>
     </section>
 
     <section id="metricsSection">