Power Point causing audio problems in presentation mode only

Question

Hello,

we have a lecture hall with projector and audio system. The system has worked fine the last years.

Since this year, for one presenter, power point causes audio problems when switched to presentation mode and only then. The problem sounds like typical earth hum/like when you touch the jack mini connector with the fingers.

What is changed when PP in presentation mode? What could cause the problem?

Other laptops work just fine in this setup.

Answer 1

Dear @hanne stenzel,

Good day, and I appreciate the clear explanation of your issue. As a forum moderator, I genuinely wish I could directly access your account or delve into the backend systems to investigate and fix this for you. However, our role here is limited to providing general guidance and solutions that can be applied by users. 

From your description and my research, this appears to be a ground loop issue that becomes noticeable when PowerPoint enters full-screen Presentation Mode. In this mode, changes in graphics usage (GPU), audio routing, and power behavior can increase the likelihood of a ground loop forming between the laptop, projector, and audio system.

The low-frequency humming or buzzing you described is a typical symptom. Differences in hardware design, grounding, or power adapters often explain why other laptops do not experience the same issue.

To help isolate or resolve this, please try the following steps:

1.Run on battery only

• Unplug the laptop’s power adapter (run purely on battery).
• Start the presentation.
• If the hum disappears > it’s a ground loop caused by the power supply.

2.Use a ground loop Isolator

Insert a ground loop isolator in the audio path between the laptop and the sound system

Common options include:

• 3.5mm ground loop isolators
• HDMI audio extractors with isolation

3.Change the audio output

• Instead of sending audio through HDMI, use the laptop’s headphone jack (3.5mm) to connect to the sound system
• Alternatively, use a USB sound card or external audio interface

4.Adjust PowerPoint settings

• Go to the Slide Show tab > select Set Up Slide Show
• Try using “Browsed by an individual (window)” instead of full-screen mode
• In some cases, this avoids triggering the hardware changes that cause the issue

5.Additional checks

• Update graphics drivers and audio drivers on the problematic laptop.
• Try a different HDMI cable (preferably a high-quality shielded one).

I hope this information is helpful. Please follow these steps and let me know if it works for you. If not, we can work together to resolve this. Thank you for your patience and understanding. If you have any questions or need further assistance, please feel free to share them in the comments so I can continue to support you. I'm looking forward to your reply.

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Answer 2

In presentation mode PowerPoint changes how it renders graphics and plays embedded media, which can stress the GPU and audio pipeline differently than in edit mode. That can expose marginal hardware, driver, or grounding issues on a specific laptop, especially when connected to an external projector and hall audio system.

For the affected laptop, try these steps focused on PowerPoint and Windows settings:

1. In PowerPoint, disable hardware graphics acceleration
   • Open PowerPoint on the problematic laptop.
   • Go to File > Options > Advanced.
   • Under Display, check Disable hardware graphics acceleration.
   • Restart PowerPoint and test in Slide Show (presentation) mode.
2. Reduce video/special effects load in the presentation
   • If the presentation contains embedded videos, compress them to reduce processing load: use File > Info > Compress Media as described in Compress the media files in your presentation.
   • Limit heavy effects (shadows, reflections, glow, soft edges, bevels, 3‑D rotation) on videos or animated objects, which can increase GPU and power draw in Slide Show mode.
3. Update and verify display and audio drivers
   • On the affected laptop, update the video card driver from the manufacturer’s site and ensure it is current, as recommended for improving playback.
   • Do the same for the audio driver.
   • After updating, reboot and test again in presentation mode.
4. Check hardware and resource load
   • Ensure there is enough free disk space on the laptop’s system drive.
   • Close all other programs before starting the presentation so PowerPoint and the audio driver have maximum resources.
5. Test with different media handling
   • If the presentation uses linked media, embed the media instead and then run File > Info > Optimize Compatibility so PowerPoint can adjust the media for more reliable playback.
   • If the media was created in an older PowerPoint version, convert the file: File > Info > Convert to upgrade embedded media to the current format and then run Optimize Compatibility again.
6. Clean temporary files
   • Excess TEMP files can slow PowerPoint and contribute to glitches.
   • Close all apps, press Start > Run, type %temp%, press OK, and delete excess .tmp files that are not in use.

If the hum only appears with this one laptop and only when Slide Show starts, it is likely a combination of this laptop’s GPU/audio driver behavior under full‑screen rendering plus the hall’s audio grounding. The above steps reduce GPU load and stabilize media playback, which often eliminates such noise.

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References:

• Tips for improving audio and video playback and compatibility in PowerPoint
• Are you having video or audio playback issues?
• PowerPoint isn't responding, hangs or freezes
• Fixes or workarounds for recent issues in PowerPoint for Windows