August 16 2013 - 9:34 am

Toggle Stereo/Mono Audio Output

Correspondent Simon Crosbie has set up an amp and pair of speakers in his workshop which is connected to an Airport Express. Unfortunately, the speakers are some distance apart, so that he may be near one speaker or another at any time, and will only hear that channel’s output. Simon wanted to know if there’s a way to toggle between stereo and mono output so he can hear more than just half of a stereo recording.

Yes, there is a way. Go to System Preferences > Accessibility. Choose “Audio” in the left-hand list and in the panel that appears click the checkbox next to “Play stereo audio as mono”.

Goodnight everybody!

Wait a minute. I almost forgot I wrote this script to do it:

tell application "System Preferences"

reveal anchor "Hearing" of pane id ""

end tell

tell application "System Events"

tell application process "System Preferences"

set frontmost to true

tell window "Accessibility"

##–> pre 10.9 set monoStereoCheckbox to checkbox 2 of group 1

set monoStereoCheckbox to checkbox “Play stereo audio as mono”

if (get value of monoStereoCheckbox) as boolean is true then

set ddMessage to "Switch to STEREO output?"


set ddMessage to "Switch to MONO output?"

end if

if button returned of (display dialog ddMessage buttons {"No", "Yes"} default button 2) is "Yes" then

tell monoStereoCheckbox to click

end if

end tell

end tell

end tell

if application "System Preferences" is running then

tell application "System Preferences" to quit

end if

[UPDATE November 13, 2013: The original script has been updated for Mavericks. Note the commented line for pre-10.9 systems and the line that follows it. Set the monoStereoCheckbox variable using one or the other depending on the OS.]

[UPDATE October 17, 2014: Another change for compatibility with Yosemite. The line “set frontmost to true” is inserted right after the first tell application process "System Preferences" line near the beginning.]

I would save this script in the system wide Scripts menu (install it in ~/Library/Scripts/). Because the script uses (gulp) GUI scripting you must make sure that “Enable access for assitive devices” is checked in the Accessibility System Preferences panel.

Smarties among you can figure out how to switch mono/stereo when using AppleScript to change AirPlay speakers.

And bear in mind that while the script works with the current OS (and probably an OS that may be released this Fall), Apple may change the layout of the System Preferences panels in a future update, in which case the GUI scripting will have to be updated.

[UPDATE December 28, 2018: Mojave made some changes and the updated version of the script can be seen here.

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