StereoToMono

By: no9

Mixes stereo audio together to create mono output in both channels.

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This extension monofies the currently playing video or audio source with a single click on the extension button.

The StereoToMono extension is useful if you want to listen to the video or audio you are currently watching in mono. It combines the left speaker's content with the right speaker's and vice versa, so you effectively hear the same sound from both speakers. This can be helpful when the stereo image in the video is unbalanced, heavily leaning to the right or left, suffers from phase correlation issues, or you simply want to hear the entire audio using only one speaker.

It works on both video and audio elements on pages that support this feature. The extension is activated by clicking the left mouse button on its icon. For a full sound reset after adjusting the volume with the extension, it is recommended to reload the page.

You can set the sound in your browser permanently for the current browser session (until you quit Firefox) by using the preference setting located under the right-click menu. Please use this with caution, keeping in mind potential issues listed below.

Known issues:

On some pages, it is not possible to adjust the stereo image of the played elements. This is due to how the specific page is designed.
On some pages, when clicking on the extension button, the browser may mute the sound. This is due to the security configuration of the specific page or the server it is hosted on and unfortunately cannot be detected from the extension's point of view.
This addon may interfere with other extensions that also alter the sound at the same time. Please keep this in mind.

If you find this extension useful, you may consider supporting the author with a donation of any amount. Check the menu by right-clicking the extension button.

Add-on

By:

no9

Daily users:

576 24

Rating:

4.64

(11)

Version:

1.2 Last updated: 2023-08-02

Version code:

5603264

Creation date:

2022-08-29

Risk:

Permissions:

activeTab
contextMenus
storage

Size:

74.34KB

Full description:

Source:

Firefox Add-ons Store

Data ingested on:

2025-07-20

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Ranking

# 4,229 ▲ 94

Other rankings

#333 in Games & Entertainment ▲ 7 #138 in channel keyword 39 #176 in audio keyword 52 ▲ 2

Other platforms

StereoToMono (v1.0)

7,000 4.45

(51)

User reviews

Users find StereoToMono very useful for converting stereo audio to mono, especially for videos with audio only in one ear. It works well across multiple platforms and enhances user experience. However, some users are concerned about the add-on's broad permissions that can access data on all visited websites, which raises privacy concerns and leads to disabling the extension despite its benefits.

Pros

Effectively converts stereo audio to mono, improving audio experience on videos where sound is only in one ear.
Works well across various websites like YouTube and TikTok.
Simple and helpful for users who dislike stereo separation in music or videos.
No apparent performance or functional issues noted, works reliably as intended.

Cons

Requires broad permissions to access data on all websites, raising privacy and security concerns.
Permission prompts cause some users to distrust or disable the add-on despite its functionality.

Recent reviews

by Za*****, 2025-06-08

thank you for this extension! I despise it when music tries to get funky and have different instruments in different ears, but I didn't want to force mono through windows, since I also play games...

by ty*****, 2025-05-03

by 全民*****, 2025-03-31

View all user reviews ›

Extension safety

Risk impact

Risk impact measures the level of extra permissions an extension has access to. A low risk impact extension cannot do much harms, whereas a high risk impact extension can do a lot of damage like stealing your password, bypassing your security settings, and accessing your personal data. High risk impact extensions are not necessarily malicious. However, if they do turn malicious, they can be very harmful.

StereoToMono requires a few sensitive permissions. Exercise caution before installing.

Risk impact analysis details

Critical Allows access to all websites, posing a significant security risk as it can monitor and modify data from any visited site.
High ******* ******* **** *** ****** ***** *** ***** ** ******* **** ********* ********* ** * *********** *****

Risk likelihood

Risk likelihood measures the probability that a Firefox add-on may turn malicious. This is determined by the publisher and the Firefox add-on reputation on Firefox Add-ons Store, the amount of time the Firefox add-on has been around, and other signals about the Firefox add-on. Our algorithms are not perfect, and are subject to change as we discover new ways to detect malicious extensions. We recommend that you always exercise caution when installing a Firefox add-on.

StereoToMono has earned a fairly good reputation and likely can be trusted.

Risk likelihood analysis details

High This extension has low user count. Unpopular extensions may not be stable or safe.
Low **** ********* *** ******* **** **** * ****** **** ***** ******** *** **** ****** ** ** ****** *** *****
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