Quick Answer: A projector with picture but no sound almost always comes down to one of four causes: the source is sending a Dolby Digital/DTS bitstream the projector’s audio chip can’t decode instead of plain PCM stereo, the wrong audio output device is still selected on a connected laptop, the projector has no built-in speaker at all (common on business and higher-end home theater models), or a bad cable/adapter — especially HDMI-to-VGA — is dropping the audio channel entirely. Working through those four in order fixes the overwhelming majority of “no sound” cases without touching any settings menu twice.
Losing audio while the picture keeps working is one of the most confusing projector problems, because it feels like it should be simple — the cable is clearly carrying something. This guide breaks down the real causes in the order worth checking them, instead of guessing at a factory reset.
By the numbers: Per Epson’s own official troubleshooting documentation, the fix for “there is no sound” over HDMI is specifically to set the source device’s Sound Output Format to PCM in its audio settings, since HDMI can carry either compressed surround bitstreams or plain PCM and not every projector’s onboard audio processor decodes both. Separately, per BenQ’s own knowledge-center guidance on external speakers, a meaningful share of current home-theater and business projectors ship with no built-in speaker at all by design — a spec worth confirming on the sheet before assuming a defect.
The four real causes of no sound
| Symptom | Likely cause | Fix |
|---|---|---|
| Picture works, total silence on every source | Bitstream/PCM audio-format mismatch | Set source's audio output to PCM/Stereo instead of Dolby Digital, DTS, or "Auto" |
| Sound still plays through the laptop, not the projector | Wrong audio output device selected in the OS | Manually pick the projector/HDMI entry in the computer's sound settings |
| No sound on this model, ever, on any source | Projector has no built-in speaker | Check the spec sheet for a listed speaker wattage; add external speakers if none exists |
| Sound worked before, stopped after a cable/adapter swap | Adapter strips audio (e.g. HDMI-to-VGA) or bad cable | Swap in a certified HDMI cable and avoid analog-video adapters for the audio path |
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Cause 1: Bitstream vs. PCM audio-format mismatch
This is the most common cause of total silence, and it has nothing to do with volume or muting. HDMI can carry audio two fundamentally different ways: as a compressed surround bitstream (Dolby Digital, DTS) meant for an AV receiver to decode, or as plain PCM stereo that almost any device can play back directly. Many projectors’ built-in audio chips only understand PCM — if the source device is set to “Auto” or a bitstream format and defaults to sending Dolby Digital over HDMI, the projector simply has nothing it can decode, and the result is silence with a perfectly good picture.
The fix, per Epson’s own troubleshooting documentation, is to open the source device’s audio output settings — this could be a streaming box, game console, or PC — and force the format to PCM or “Stereo” instead of a bitstream option. This is also the exact same underlying mismatch that causes some soundbars to go silent over an ARC connection; if you’re specifically routing audio back out to a soundbar rather than listening through the projector’s own speaker, our HDMI ARC guide covers that return path in detail.
Cause 2: The computer is still playing sound through its own speakers
Connecting an HDMI cable to a laptop adds the projector as an available audio output device — it does not automatically switch to it. This is an operating-system behavior, not a projector fault, and it’s an especially common trap in classrooms and conference rooms where someone plugs in, sees the picture appear, and assumes audio routing worked the same way. The fix is to open the computer’s sound settings and manually select the projector (it typically shows up under its own model name or as a generic “HDMI” / “Digital Audio” device) as the active output, rather than leaving it on the built-in laptop speakers.
Cause 3: The projector has no built-in speaker
Not every projector has a speaker to begin with, and this is easy to miss when buying based on brightness or resolution specs alone. Per BenQ’s own knowledge-center guidance on external speakers, a real share of current home-theater and business-focused projectors skip a built-in speaker entirely, on the assumption that anyone buying at that tier is already pairing the unit with an AV receiver or a dedicated soundbar. If a projector has genuinely never produced sound on any source or cable, checking the model’s own spec sheet for a listed speaker wattage (most that do include one state it plainly, e.g. “5W mono speaker” or “2x 8W stereo”) is the fastest way to confirm whether a speaker exists at all before troubleshooting further. If it doesn’t, the fix isn’t a setting — it’s adding external speakers, which our best external speakers for projectors guide covers by connection type.
Cause 4: A bad cable or the wrong adapter
Some adapters silently drop audio because the format they convert to physically has no audio channel — HDMI-to-VGA is the classic case, since VGA is a video-only analog standard. If sound worked before and stopped right after switching to an adapter or a different cable, that’s the first thing to reverse. A damaged or non-compliant HDMI cable can produce the identical symptom even without an adapter in the chain, so swapping in a known-good certified cable — our best HDMI cable for projector picks are verified for full audio-plus-video bandwidth — rules this out cheaply before assuming a deeper fault.
The bottom line
Total silence with a working picture is almost never a broken projector: check the source’s audio output format first (PCM, not a bitstream), confirm the right output device is actually selected if a computer is involved, verify the projector even has a built-in speaker to begin with, and rule out a stripped-audio adapter or bad cable last. Work through those four in order before assuming a hardware fault. If audio plays fine on the projector itself but a paired soundbar stays silent, that’s a different, ARC-specific problem — see our HDMI ARC guide for that fix instead.
Guidance verified August 2026 against manufacturer troubleshooting documentation (Epson, BenQ) and subject to change; check your specific model’s manual for exact settings menu labels.