diff --git a/.github/workflows/seo-check.yml b/.github/workflows/seo-check.yml
index ce55816..39ca87c 100644
--- a/.github/workflows/seo-check.yml
+++ b/.github/workflows/seo-check.yml
@@ -16,3 +16,11 @@ jobs:
       - run: pip install beautifulsoup4
       - name: FAQPage JSON-LD matches the visible FAQ
         run: python3 scripts/seo_sync.py --check
+      - name: Text to Speech pages don't use the word "AI"
+        # People searching "text to speech -ai" exclude pages containing the word, and they find this page in the
+        # top 10 (Search Console, Oct 2026). One "AI" anywhere on the page would drop it from those results.
+        run: |
+          if grep -nwi 'ai' text-to-speech/index.html zh/text-to-speech/index.html; then
+            echo '::error::The word "AI" appeared on a Text to Speech page; see the comment in seo-check.yml.'
+            exit 1
+          fi
diff --git a/audio-joiner/index.html b/audio-joiner/index.html
index ad5ebc1..f610e75 100644
--- a/audio-joiner/index.html
+++ b/audio-joiner/index.html
@@ -54,6 +54,22 @@
                     "text": "Add the MP3 files, arrange them in order, optionally set a crossfade, then click Merge & Download. You get one MP3 or WAV file, made in your browser."
                 }
             },
+            {
+                "@type": "Question",
+                "name": "How do I combine two audio files?",
+                "acceptedAnswer": {
+                    "@type": "Answer",
+                    "text": "Add both files, put them in the order you want and click Merge & Download: the second file plays right after the first. A crossfade blends the end of the first into the start of the second."
+                }
+            },
+            {
+                "@type": "Question",
+                "name": "Can I overlay two audio files so they play at the same time?",
+                "acceptedAnswer": {
+                    "@type": "Answer",
+                    "text": "Not yet. Audio Joiner plays files one after another; mixing tracks on top of each other, such as a voice over music, is not available yet."
+                }
+            },
             {
                 "@type": "Question",
                 "name": "Can I merge different formats?",
@@ -223,7 +239,7 @@ <h1>Merge Audio Files</h1>
 
         <section class="seo-content">
             <h2>Merge MP3 and other audio files online</h2>
-            <p>Add your files, put them in order and download one file. Audio Joiner runs entirely in your browser: the files are decoded, joined and encoded on your device, so nothing is uploaded, and there is no size quota and no waiting in line.</p>
+            <p>Audio Joiner is a free online audio merger and MP3 joiner: add your files, put them in order and download one file. It runs entirely in your browser: the files are decoded, joined and encoded on your device, so nothing is uploaded, and there is no size quota and no waiting in line.</p>
             <h3>How to merge audio files</h3>
             <ol>
                 <li>Drop your files on the box above, or click to choose them. You can add more later with “Add more files”.</li>
@@ -231,7 +247,7 @@ <h3>How to merge audio files</h3>
                 <li>Optionally set a crossfade of up to 3 seconds for a smooth transition. Leave it at 0 for a straight cut.</li>
                 <li>Click “Merge &amp; Download” and save the result as MP3 (192 kbps) or WAV.</li>
             </ol>
-            <h3>What you can merge</h3>
+            <h3>Combine audio files of any format</h3>
             <p>MP3, WAV, M4A/AAC, FLAC, OGG and Opus files, mixed in any order: anything your browser can play. Voice messages saved from WhatsApp or Telegram (.opus, .ogg) work in browsers that play Opus, such as Chrome, Edge and Firefox. Mono and stereo files can be mixed, and files with different sample rates are brought to one rate automatically.</p>
             <h3>Common uses</h3>
             <ul>
@@ -251,6 +267,8 @@ <h3>Limits</h3>
         <section class="faq">
             <h2>Frequently Asked Questions</h2>
             <div class="faq-item"><div class="faq-q">How do I merge MP3 files into one?</div><div class="faq-a">Add the MP3 files, arrange them in order, optionally set a crossfade, then click Merge &amp; Download. You get one MP3 or WAV file, made in your browser.</div></div>
+            <div class="faq-item"><div class="faq-q">How do I combine two audio files?</div><div class="faq-a">Add both files, put them in the order you want and click Merge &amp; Download: the second file plays right after the first. A crossfade blends the end of the first into the start of the second.</div></div>
+            <div class="faq-item"><div class="faq-q">Can I overlay two audio files so they play at the same time?</div><div class="faq-a">Not yet. Audio Joiner plays files one after another; mixing tracks on top of each other, such as a voice over music, is not available yet.</div></div>
             <div class="faq-item"><div class="faq-q">Can I merge different formats?</div><div class="faq-a">Yes. MP3, WAV, M4A, FLAC, OGG and Opus can be mixed in one merge. Each file is decoded by your browser and the result is saved as MP3 or WAV.</div></div>
             <div class="faq-item"><div class="faq-q">Can I combine WhatsApp or Telegram voice messages?</div><div class="faq-a">Yes. Save the voice messages from the chat (they are .opus or .ogg files) and add them here. Chrome, Edge and Firefox play these files; some older Safari versions do not.</div></div>
             <div class="faq-item"><div class="faq-q">Does merging reduce audio quality?</div><div class="faq-a">Saving as WAV keeps the decoded audio unchanged. Saving as MP3 re-encodes it at 192 kbps, which sounds the same as the original for speech and most music.</div></div>
diff --git a/audio-speed-changer/index.html b/audio-speed-changer/index.html
index 7a633b5..c81a9a8 100644
--- a/audio-speed-changer/index.html
+++ b/audio-speed-changer/index.html
@@ -14,30 +14,30 @@
       gtag('config', 'G-62ZJNZFRES');
     </script>
 
-    <title>Audio Speed Changer — Slow Down / Speed Up | AudioTools.dev</title>
-    <meta name="description" content="Change audio playback speed online for free. Slow down or speed up MP3, WAV files without pitch change. No upload, runs in browser.">
-    <meta name="keywords" content="audio speed changer, slow down audio, speed up mp3, change audio speed online, audio tempo changer, slow down music, speed up audio file">
+    <title>Audio Speed Changer &amp; Slow Downer Online | AudioTools.dev</title>
+    <meta name="description" content="Slow down or speed up MP3, M4A or WAV from 0.25x to 4x without changing pitch: learn a song, practise a language or listen faster. Free, no upload.">
+    <meta name="keywords" content="audio speed changer, audio slow downer, slow down audio, slow down mp3, slow down m4a, slow down wav, slow down a song, speed up audio, change speed without changing pitch">
     <link rel="canonical" href="https://audiotools.dev/audio-speed-changer/">
     <meta property="og:type" content="website">
     <meta property="og:site_name" content="AudioTools.dev">
     <meta property="og:locale" content="en_US">
     <meta property="og:url" content="https://audiotools.dev/audio-speed-changer/">
-    <meta property="og:title" content="Audio Speed Changer — Slow Down / Speed Up | AudioTools">
-    <meta property="og:description" content="Change audio playback speed online for free. Slow down or speed up MP3, WAV files without pitch change. No upload, runs in browser.">
+    <meta property="og:title" content="Audio Speed Changer &amp; Slow Downer Online">
+    <meta property="og:description" content="Slow down or speed up MP3, M4A or WAV from 0.25x to 4x without changing pitch: learn a song, practise a language or listen faster. Free, no upload.">
     <meta property="og:image" content="https://audiotools.dev/og/audio-speed-changer.png">
     <meta property="og:image:width" content="1200">
     <meta property="og:image:height" content="630">
-    <meta property="og:image:alt" content="Audio Speed Changer — Slow Down / Speed Up | AudioTools">
+    <meta property="og:image:alt" content="Audio Speed Changer &amp; Slow Downer Online">
     <meta name="twitter:card" content="summary_large_image">
-    <meta name="twitter:title" content="Audio Speed Changer — Slow Down / Speed Up | AudioTools">
-    <meta name="twitter:description" content="Change audio playback speed online for free. Slow down or speed up MP3, WAV files without pitch change. No upload, runs in browser.">
+    <meta name="twitter:title" content="Audio Speed Changer &amp; Slow Downer Online">
+    <meta name="twitter:description" content="Slow down or speed up MP3, M4A or WAV from 0.25x to 4x without changing pitch: learn a song, practise a language or listen faster. Free, no upload.">
     <meta name="twitter:image" content="https://audiotools.dev/og/audio-speed-changer.png">
     <meta name="robots" content="index, follow, max-snippet:-1, max-image-preview:large">
     <link rel="icon" type="image/svg+xml" href="/favicon.svg">
     <link rel="icon" type="image/x-icon" href="/favicon.ico">
     <link rel="apple-touch-icon" href="/apple-touch-icon.png">
     <script type="application/ld+json">
-    {"@context":"https://schema.org","@type":"WebApplication","name":"Audio Speed Changer — AudioTools.dev","url":"https://audiotools.dev/audio-speed-changer/","description":"Change audio playback speed online for free. Slow down or speed up MP3, WAV files without pitch change. No upload, runs in browser.","applicationCategory":"MultimediaApplication","operatingSystem":"Any","isAccessibleForFree":true,"offers":{"@type":"Offer","price":"0","priceCurrency":"USD"}}
+    {"@context":"https://schema.org","@type":"WebApplication","name":"Audio Speed Changer — AudioTools.dev","url":"https://audiotools.dev/audio-speed-changer/","description":"Slow down or speed up MP3, M4A or WAV from 0.25x to 4x without changing pitch: learn a song, practise a language or listen faster. Free, no upload.","applicationCategory":"MultimediaApplication","operatingSystem":"Any","isAccessibleForFree":true,"offers":{"@type":"Offer","price":"0","priceCurrency":"USD"}}
     </script>
     <script type="application/ld+json">
     {
@@ -46,18 +46,34 @@
         "mainEntity": [
             {
                 "@type": "Question",
-                "name": "Can I change speed without pitch change?",
+                "name": "How do I slow down an audio file without changing the pitch?",
                 "acceptedAnswer": {
                     "@type": "Answer",
-                    "text": "Yes. The tool uses WSOLA time-stretching to preserve original pitch while adjusting playback speed from 0.25x to 4x."
+                    "text": "Drop the file here, choose a speed below 1x (for example 0.75x) and click Apply & Process. WSOLA time-stretching keeps the original pitch; download the result as MP3 or WAV."
                 }
             },
             {
                 "@type": "Question",
-                "name": "What formats are supported?",
+                "name": "Can I slow down an M4A or WAV file?",
                 "acceptedAnswer": {
                     "@type": "Answer",
-                    "text": "MP3, WAV, FLAC, OGG, AAC, M4A, WebM. Output is saved as MP3 or WAV."
+                    "text": "Yes. MP3, M4A/AAC, WAV, FLAC, OGG and WebM all work. The result is saved as MP3 or WAV."
+                }
+            },
+            {
+                "@type": "Question",
+                "name": "What speed is best for learning a song?",
+                "acceptedAnswer": {
+                    "@type": "Answer",
+                    "text": "Start at 0.5x–0.75x and raise the speed as the part becomes comfortable. The pitch stays the same, so you can play along in the original key."
+                }
+            },
+            {
+                "@type": "Question",
+                "name": "Can I speed up a podcast or voice message?",
+                "acceptedAnswer": {
+                    "@type": "Answer",
+                    "text": "Yes. Choose 1.25x–2x and download the result. A 60-minute recording takes 40 minutes at 1.5x."
                 }
             },
             {
@@ -145,7 +161,7 @@
         <section class="hero">
             <svg class="hero-glyph" viewBox="0 0 160 56" aria-hidden="true"><path class="g-ink" d="M4 28 C14 6 24 6 34 28 S54 50 64 28"/><polyline class="g-acc" points="74,28 78,12 82,44 86,12 90,44 94,12 98,44 102,12 106,44 110,12 114,44 118,12 122,44 126,12 130,44 134,12 138,44 142,12 146,44 150,28"/></svg>
             <h1>Audio Speed Changer</h1>
-            <p>Slow down or speed up any audio file — adjust tempo without changing the pitch</p>
+            <p>Slow down or speed up any audio file — MP3, M4A, WAV — without changing the pitch</p>
         </section>
 
         <div class="tool-area">
@@ -204,21 +220,34 @@ <h1>Audio Speed Changer</h1>
         </div>
 
         <section class="seo-content">
-            <h2>Free Online Audio Speed Changer</h2>
-            <p>Audio Speed Changer lets you adjust the playback speed of any audio file from 0.25x (4x slower) to 4x faster, while preserving the original pitch. Perfect for language learning, music practice, transcription work, and podcast listening.</p>
-            <h3>Speed Change with Pitch Preservation</h3>
-            <p>A naive speed change also alters pitch — making things sound higher when sped up and lower when slowed down. This tool uses a WSOLA (Waveform Similarity Overlap-Add) time-stretching algorithm to change speed while keeping the original pitch, so voices and music sound natural at any speed.</p>
-            <h3>How It Works</h3>
-            <p>Drop or select your audio file, choose a speed with the slider or a preset, then click "Apply &amp; Process". The file is decoded with the Web Audio API, time-stretched directly in your browser, and offered for download as MP3 or WAV. Nothing is uploaded to any server.</p>
-            <h3>Common Use Cases</h3>
-            <p>Language learning — slow down native speakers to catch every word. Music practice — slow down guitar solos or drum patterns to learn at your pace. Transcription — slow down recordings for accurate typing. Podcasts — speed up to 1.5–2x to listen faster.</p>
-            <p>Need other edits? Try our <a href="/audio-trimmer/">Audio Trimmer</a>, <a href="/converter/">Audio Converter</a>, <a href="/text-to-speech/">Text to Speech</a>, or <a href="/voice-to-text/">Voice to Text</a>.</p>
+            <h2>Slow down or speed up audio without changing pitch</h2>
+            <p>Audio Speed Changer is an online audio slow downer and speed changer. It plays any recording from 0.25x (four times slower) to 4x faster and keeps the original pitch, so a slowed-down song stays in its key and a sped-up voice does not turn into a chipmunk. It runs in your browser: nothing is uploaded.</p>
+            <h3>How to slow down an audio file</h3>
+            <ol>
+                <li>Drop an MP3, M4A, WAV or other audio file on the box above.</li>
+                <li>Pick a preset (0.5x, 0.75x, 1.25x, 1.5x, 2x) or set any speed from 0.25x to 4x with the slider.</li>
+                <li>Click “Apply &amp; Process” and listen to the result.</li>
+                <li>Download it as MP3 or WAV.</li>
+            </ol>
+            <h3>Slow down a song to learn it</h3>
+            <p>Guitar solos, piano parts and drum fills are easier to learn at 0.5x–0.75x. Because the pitch stays the same, you can play along in the original key. To loop one passage, cut it out first with the <a href="/audio-trimmer/">audio trimmer</a>, then slow it down here.</p>
+            <h3>Slow down speech for language learning and transcription</h3>
+            <p>At 0.75x, native speakers become much easier to follow without sounding unnatural. For typing up an interview or a lecture by hand, 0.5x–0.75x lets you keep up with the speaker.</p>
+            <h3>Speed up podcasts, lectures and voice messages</h3>
+            <p>At 1.5x, a 60-minute lecture takes 40 minutes; at 2x, 30. The result is a shorter file you can keep and play anywhere, not just a faster player setting.</p>
+            <h3>Pitch stays put</h3>
+            <p>A naive speed change also shifts pitch: higher when sped up, lower when slowed down. This tool uses WSOLA (Waveform Similarity Overlap-Add) time-stretching, which changes the tempo while keeping the original pitch, so voices and instruments sound natural.</p>
+            <h3>Supported formats</h3>
+            <p>MP3, M4A/AAC, WAV, FLAC, OGG and WebM: anything your browser can play. The result is saved as MP3 or WAV; for M4A or FLAC, convert it afterwards with the <a href="/converter/">audio converter</a>.</p>
+            <p>Want the words instead? <a href="/voice-to-text/">Voice to text</a> transcribes a recording on your device. To join several recordings first, use the <a href="/audio-joiner/">audio joiner</a>.</p>
         </section>
 
         <section class="faq">
             <h2>Frequently Asked Questions</h2>
-            <div class="faq-item"><div class="faq-q">Can I change speed without pitch change?</div><div class="faq-a">Yes. The tool uses WSOLA time-stretching to preserve original pitch while adjusting playback speed from 0.25x to 4x.</div></div>
-            <div class="faq-item"><div class="faq-q">What formats are supported?</div><div class="faq-a">MP3, WAV, FLAC, OGG, AAC, M4A, WebM. Output is saved as MP3 or WAV.</div></div>
+            <div class="faq-item"><div class="faq-q">How do I slow down an audio file without changing the pitch?</div><div class="faq-a">Drop the file here, choose a speed below 1x (for example 0.75x) and click Apply &amp; Process. WSOLA time-stretching keeps the original pitch; download the result as MP3 or WAV.</div></div>
+            <div class="faq-item"><div class="faq-q">Can I slow down an M4A or WAV file?</div><div class="faq-a">Yes. MP3, M4A/AAC, WAV, FLAC, OGG and WebM all work. The result is saved as MP3 or WAV.</div></div>
+            <div class="faq-item"><div class="faq-q">What speed is best for learning a song?</div><div class="faq-a">Start at 0.5x–0.75x and raise the speed as the part becomes comfortable. The pitch stays the same, so you can play along in the original key.</div></div>
+            <div class="faq-item"><div class="faq-q">Can I speed up a podcast or voice message?</div><div class="faq-a">Yes. Choose 1.25x–2x and download the result. A 60-minute recording takes 40 minutes at 1.5x.</div></div>
             <div class="faq-item"><div class="faq-q">Is my audio uploaded?</div><div class="faq-a">No. Everything happens in your browser using the Web Audio API.</div></div>
         </section>
     </div>
diff --git a/scripts/build_zh.py b/scripts/build_zh.py
index aab203d..a4d1372 100644
--- a/scripts/build_zh.py
+++ b/scripts/build_zh.py
@@ -196,6 +196,10 @@ def update_hand_made(path, current, en_href):
      '<div class="faq-q">我的音频会被上传吗？</div><div class="faq-a">不会。所有处理都通过 Web Audio API 在您的浏览器中完成。</div>'),
 ],
 'audio-joiner': [
+    ('<div class="faq-q">How do I combine two audio files?</div><div class="faq-a">Add both files, put them in the order you want and click Merge &amp; Download: the second file plays right after the first. A crossfade blends the end of the first into the start of the second.</div>',
+     '<div class="faq-q">如何把两个音频文件合在一起？</div><div class="faq-a">添加两个文件，按想要的顺序排列，点击“合并并下载”：第二个文件会紧接着第一个播放。淡入淡出可以让第一个文件的结尾平滑过渡到第二个文件的开头。</div>'),
+    ('<div class="faq-q">Can I overlay two audio files so they play at the same time?</div><div class="faq-a">Not yet. Audio Joiner plays files one after another; mixing tracks on top of each other, such as a voice over music, is not available yet.</div>',
+     '<div class="faq-q">可以叠加两个音频，让它们同时播放吗？</div><div class="faq-a">暂时不行。音频合并是把文件一个接一个地连起来；把多条音轨叠在一起（例如人声配背景音乐）的功能还没有。</div>'),
     ('"name":"Audio Joiner — AudioTools.dev"',
      '"name":"音频合并 — AudioTools.dev"'),
     ('<p><strong>Drop audio files here</strong> or click to browse</p>',
@@ -254,8 +258,8 @@ def update_hand_made(path, current, en_href):
      '<p>把 MP3、语音消息等音频合并成一条音轨——可调整顺序、淡入淡出，无需上传</p>'),
     ('<h2>Merge MP3 and other audio files online</h2>',
      '<h2>在线合并 MP3 等音频文件</h2>'),
-    ('<p>Add your files, put them in order and download one file. Audio Joiner runs entirely in your browser: the files are decoded, joined and encoded on your device, so nothing is uploaded, and there is no size quota and no waiting in line.</p>',
-     '<p>添加文件、排好顺序，下载一个文件即可。音频合并完全在浏览器中运行：文件在您的设备上解码、拼接和编码，因此不上传任何内容，没有大小配额，也不用排队等待。</p>'),
+    ('<p>Audio Joiner is a free online audio merger and MP3 joiner: add your files, put them in order and download one file. It runs entirely in your browser: the files are decoded, joined and encoded on your device, so nothing is uploaded, and there is no size quota and no waiting in line.</p>',
+     '<p>音频合并是一款免费的在线音频合并、MP3 拼接工具：添加文件、排好顺序，下载一个文件即可。它完全在浏览器中运行：文件在您的设备上解码、拼接和编码，因此不上传任何内容，没有大小配额，也不用排队等待。</p>'),
     ('<h3>How to merge audio files</h3>',
      '<h3>如何合并音频文件</h3>'),
     ('<li>Drop your files on the box above, or click to choose them. You can add more later with “Add more files”.</li>',
@@ -266,8 +270,8 @@ def update_hand_made(path, current, en_href):
      '<li>可选：设置最长 3 秒的淡入淡出，让过渡更平滑。保持 0 则直接衔接。</li>'),
     ('<li>Click “Merge &amp; Download” and save the result as MP3 (192 kbps) or WAV.</li>',
      '<li>点击“合并并下载”，将结果保存为 MP3（192 kbps）或 WAV。</li>'),
-    ('<h3>What you can merge</h3>',
-     '<h3>可以合并哪些文件</h3>'),
+    ('<h3>Combine audio files of any format</h3>',
+     '<h3>合并任意格式的音频文件</h3>'),
     ('<p>MP3, WAV, M4A/AAC, FLAC, OGG and Opus files, mixed in any order: anything your browser can play. Voice messages saved from WhatsApp or Telegram (.opus, .ogg) work in browsers that play Opus, such as Chrome, Edge and Firefox. Mono and stereo files can be mixed, and files with different sample rates are brought to one rate automatically.</p>',
      '<p>MP3、WAV、M4A/AAC、FLAC、OGG 和 Opus 文件可按任意顺序混合，只要浏览器能播放即可。从 WhatsApp 或 Telegram 保存的语音消息（.opus、.ogg）在支持 Opus 的浏览器中可用，例如 Chrome、Edge 和 Firefox。单声道和立体声可以混合，不同采样率的文件会自动统一。</p>'),
     ('<h3>Common uses</h3>',
diff --git a/zh/audio-joiner/index.html b/zh/audio-joiner/index.html
index adfb86f..b1ebc00 100644
--- a/zh/audio-joiner/index.html
+++ b/zh/audio-joiner/index.html
@@ -54,6 +54,22 @@
                     "text": "添加 MP3 文件，排好顺序，可选设置淡入淡出，然后点击“合并并下载”。您会得到一个在浏览器中生成的 MP3 或 WAV 文件。"
                 }
             },
+            {
+                "@type": "Question",
+                "name": "如何把两个音频文件合在一起？",
+                "acceptedAnswer": {
+                    "@type": "Answer",
+                    "text": "添加两个文件，按想要的顺序排列，点击“合并并下载”：第二个文件会紧接着第一个播放。淡入淡出可以让第一个文件的结尾平滑过渡到第二个文件的开头。"
+                }
+            },
+            {
+                "@type": "Question",
+                "name": "可以叠加两个音频，让它们同时播放吗？",
+                "acceptedAnswer": {
+                    "@type": "Answer",
+                    "text": "暂时不行。音频合并是把文件一个接一个地连起来；把多条音轨叠在一起（例如人声配背景音乐）的功能还没有。"
+                }
+            },
             {
                 "@type": "Question",
                 "name": "可以合并不同格式的文件吗？",
@@ -223,7 +239,7 @@ <h1>音频合并</h1>
 
         <section class="seo-content">
             <h2>在线合并 MP3 等音频文件</h2>
-            <p>添加文件、排好顺序，下载一个文件即可。音频合并完全在浏览器中运行：文件在您的设备上解码、拼接和编码，因此不上传任何内容，没有大小配额，也不用排队等待。</p>
+            <p>音频合并是一款免费的在线音频合并、MP3 拼接工具：添加文件、排好顺序，下载一个文件即可。它完全在浏览器中运行：文件在您的设备上解码、拼接和编码，因此不上传任何内容，没有大小配额，也不用排队等待。</p>
             <h3>如何合并音频文件</h3>
             <ol>
                 <li>把文件拖放到上方的框中，或点击选择。之后还可以用“添加更多文件”继续添加。</li>
@@ -231,7 +247,7 @@ <h3>如何合并音频文件</h3>
                 <li>可选：设置最长 3 秒的淡入淡出，让过渡更平滑。保持 0 则直接衔接。</li>
                 <li>点击“合并并下载”，将结果保存为 MP3（192 kbps）或 WAV。</li>
             </ol>
-            <h3>可以合并哪些文件</h3>
+            <h3>合并任意格式的音频文件</h3>
             <p>MP3、WAV、M4A/AAC、FLAC、OGG 和 Opus 文件可按任意顺序混合，只要浏览器能播放即可。从 WhatsApp 或 Telegram 保存的语音消息（.opus、.ogg）在支持 Opus 的浏览器中可用，例如 Chrome、Edge 和 Firefox。单声道和立体声可以混合，不同采样率的文件会自动统一。</p>
             <h3>常见用途</h3>
             <ul>
@@ -251,6 +267,8 @@ <h3>限制</h3>
         <section class="faq">
             <h2>常见问题</h2>
             <div class="faq-item"><div class="faq-q">如何把多个 MP3 合并成一个？</div><div class="faq-a">添加 MP3 文件，排好顺序，可选设置淡入淡出，然后点击“合并并下载”。您会得到一个在浏览器中生成的 MP3 或 WAV 文件。</div></div>
+            <div class="faq-item"><div class="faq-q">如何把两个音频文件合在一起？</div><div class="faq-a">添加两个文件，按想要的顺序排列，点击“合并并下载”：第二个文件会紧接着第一个播放。淡入淡出可以让第一个文件的结尾平滑过渡到第二个文件的开头。</div></div>
+            <div class="faq-item"><div class="faq-q">可以叠加两个音频，让它们同时播放吗？</div><div class="faq-a">暂时不行。音频合并是把文件一个接一个地连起来；把多条音轨叠在一起（例如人声配背景音乐）的功能还没有。</div></div>
             <div class="faq-item"><div class="faq-q">可以合并不同格式的文件吗？</div><div class="faq-a">可以。MP3、WAV、M4A、FLAC、OGG 和 Opus 可以在一次合并中混用。每个文件由浏览器解码，结果保存为 MP3 或 WAV。</div></div>
             <div class="faq-item"><div class="faq-q">可以合并 WhatsApp 或 Telegram 的语音消息吗？</div><div class="faq-a">可以。从聊天中保存语音消息（.opus 或 .ogg 文件），然后添加到这里。Chrome、Edge 和 Firefox 可以播放这类文件，部分旧版 Safari 不行。</div></div>
             <div class="faq-item"><div class="faq-q">合并会降低音质吗？</div><div class="faq-a">保存为 WAV 时，解码后的音频保持不变。保存为 MP3 时会以 192 kbps 重新编码，对语音和大多数音乐来说听起来与原文件相同。</div></div>