diff --git a/examples/client_browser.html b/examples/client_browser.html
index ae66a11..508e31c 100644
--- a/examples/client_browser.html
+++ b/examples/client_browser.html
@@ -56,6 +56,7 @@
 
   <div class="row" style="margin-top: 1rem;">
     <button id="connect">Connect</button>
+    <button id="testAudio" disabled>Test audio</button>
     <button id="speak" disabled>Speak streaming</button>
     <button id="stop" class="stop" disabled>Stop</button>
   </div>
@@ -77,17 +78,52 @@
     const nextSeq = () => ++seq;
 
     const ensureAudioContext = async () => {
+      const AudioContextCtor = window.AudioContext || window.webkitAudioContext;
       if (!audioCtx) {
-        audioCtx = new (window.AudioContext || window.webkitAudioContext)({ sampleRate: 24000 });
+        audioCtx = new AudioContextCtor({ sampleRate: 24000 });
+      }
+      if (audioCtx.state === 'closed') {
+        audioCtx = new AudioContextCtor({ sampleRate: 24000 });
       }
       if (audioCtx.state === 'suspended') {
+        log(`Resuming AudioContext (state=${audioCtx.state}) ...`);
         await audioCtx.resume();
+        // Some browsers need a moment before currentTime starts advancing.
+        let attempts = 0;
+        while (audioCtx.state !== 'running' && attempts < 20) {
+          await new Promise((r) => setTimeout(r, 25));
+          attempts++;
+        }
+        log(`AudioContext state after resume: ${audioCtx.state}`);
       }
     };
 
+    const playTone = async (freq = 440, duration = 0.5, amplitude = 0.5) => {
+      await ensureAudioContext();
+      const samplesCount = Math.ceil(24000 * duration);
+      const buffer = audioCtx.createBuffer(1, samplesCount, 24000);
+      const channel = buffer.getChannelData(0);
+      for (let i = 0; i < samplesCount; i++) {
+        const t = i / 24000;
+        channel[i] = amplitude * Math.sin(2 * Math.PI * freq * t) * (1 - t / duration);
+      }
+      const source = audioCtx.createBufferSource();
+      source.buffer = buffer;
+      source.connect(audioCtx.destination);
+      const startTime = audioCtx.currentTime + 0.02;
+      source.start(startTime);
+      log(`Playing test tone at ${freq} Hz for ${duration}s`);
+    };
+
     const playPcm16 = async (base64Data) => {
       await ensureAudioContext();
+      if (audioCtx.state !== 'running') {
+        throw new Error(`AudioContext not running (state=${audioCtx.state})`);
+      }
       const raw = atob(base64Data);
+      if (raw.length === 0) {
+        throw new Error('Empty audio data');
+      }
       const samples = new Int16Array(raw.length / 2);
       const view = new DataView(samples.buffer);
       for (let i = 0; i < raw.length; i += 2) {
@@ -124,6 +160,7 @@
           await ensureAudioContext();
           log('Connected');
           $('connect').disabled = true;
+          $('testAudio').disabled = false;
           $('speak').disabled = false;
           $('stop').disabled = false;
 
@@ -164,6 +201,7 @@
           log('Disconnected');
           ws = null;
           $('connect').disabled = false;
+          $('testAudio').disabled = true;
           $('speak').disabled = true;
           $('stop').disabled = true;
         };
@@ -174,6 +212,10 @@
       }
     };
 
+    $('testAudio').onclick = async () => {
+      await playTone(440, 0.6, 0.5);
+    };
+
     $('speak').onclick = async () => {
       if (!ws || ws.readyState !== WebSocket.OPEN) {
         log('Not connected');