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Every once in a while I hear a loud sound from my Mac. It sounds like either a camera shutter or a keychain lock/unlock. It all started a couple of weeks ago.

I fear something is snapping shots of my screen and beaming them somewhere.

I've scoured Google and found others have experienced the same issue. Based on suggestions, I've installed 2 Anti Virus apps (ne at a time, of course) and scanned my computer - nothing; checked Activity Monitor for unknown processes - none I could identify; looked at all the regular places (~/Library/LaunchDaemons, ~/Library/LaunchAgents, /Library/LaunchAgents) - didn't see anything out of the ordinary.

What am I missing, what else should I try, or am I just overreacting and there's a simple answer?

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Is the sound coming from your computer or is it coming from your printer. I had the same but found it was the printer –  user44829 Mar 11 '13 at 5:42
    
Have you noticed the FaceTime camera light up? i.imgur.com/Siiij6O.jpg –  David Pearce Mar 11 '13 at 14:15
    
It's coming from my computer. Muting the speaker mutes the sound (although that does not solve the problem :). The camera light DOES NOT turn on when the sound plays. I'm more afraid of a screen capture then a face capture anyway :) –  Traveling Tech Guy Mar 11 '13 at 17:46
    
Could you check if the sound you hear is the shutter or the padlock? Just play them immediatly after you heard your unsollicited sound to be sure. –  daniel Azuelos Mar 26 '13 at 9:38
1  
Why would a hacker write a sound file for taking snapshot of your screen ? –  user44516 Mar 26 '13 at 9:52

6 Answers 6

up vote 5 down vote accepted

Your search for the origin of this sound may progress on 2 paths: which application produces it and which sound is it.

Which application?

Here is an easy way to control if this sound is coming from a standard screen capture.

Type the following command twice:

ls -lu /usr/bin/screencapture

First, whenever you want. Next time, just after you heard the shutter sound.

This command will display you the time when this command was last run.

Which sound?

Quick identification

Here is a 1st attempt to be sure of which sound is used. You can't try to recognize a sound by firing an application and trying all the sound it can produce with its graphical interface.

The only practical approach is to use fast command lines just after you heard your unsollicited sound. Open a Terminal or xterm window and enter as is these 4 lines of command defining short name functions to test 4 approaching sounds:

shutter() { afplay '/System/Library/Components/CoreAudio.component/Contents/Resources/CoreAudioAUUI.bundle/Contents/Resources/Grab.aif' ; }
lock() { afplay '/System/Library/Frameworks/SecurityInterface.framework/Versions/A/Resources/lockClosing.aif' ; }
unlock() { afplay '/System/Library/Frameworks/SecurityInterface.framework/Versions/A/Resources/lockOpening.aif' ; }
safe() { afplay '/System/Library/Components/CoreAudio.component/Contents/Resources/CoreAudioAUUI.bundle/Contents/Resources/Sticky Keys Locked.aif' ; }

On Mountain Lion, these sounds have moved. Then these functions have to be defined with:

shutter() { afplay '/System/Library/Components/CoreAudio.component/Contents/SharedSupport/SystemSounds/system/Grab.aif' ; }
lock() { afplay '/System/Library/Frameworks/SecurityInterface.framework/Versions/A/Resources/lockClosing.aif' ; }
unlock() { afplay '/System/Library/Frameworks/SecurityInterface.framework/Versions/A/Resources/lockOpening.aif' ; }
safe() { afplay '/System/Library/Components/CoreAudio.component/Contents/SharedSupport/SystemSounds/accessibility/Sticky Keys Locked.aif' ; }

Keep this window open and as soon as you hear the unsollicited sound fire this four commands in turn to hear which one was played:

shutter
lock
unlock
safe

Next to be sure, you can once more verify the access time of the identified sound file with the-lu options of ls. For exemple you can confirm that the lock sound was played with:

ls -lu '/System/Library/Frameworks/SecurityInterface.framework/Versions/A/Resources/lockClosing.aif'

Deep search

If this quick approach fail, here is a command to identify the file which was used by the system to play a sound within the preceeding hour (-atime -1h):

find /Library /System/Library \( -type d \( -name "iTunes" -o -name "GarageBand" -o -name "Apple Loops" \) -prune \) -o \( \( -name "*.aif*" -o -name "*.wav*" -o -name "*.m4a*" \) -atime -1h -exec ls -luT {} \; \) 2>/dev/null

If this command doesn't report anything, the next step will be to run the same deep search within your HOME directory:

find ${HOME} \( -type d -name "iTunes" -prune \) -o \( \( -name "*.aif*" -o -name "*.wav*" -o -name "*.m4a*" \) -atime -1h -exec ls -luT {} \; \) 2>/dev/null
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Very very awesome answer. I don't have the Stickey Keys sound on Mountain Lion - is there a reference you used to pull those files together? mdfind aif | grep -v GarageBand | grep -i Sticky comes up empty for me. –  bmike Apr 3 '13 at 22:03
    
    
Still occurs - I'm thinking now it's either caused by Chrome or a hardware issue (shudder). But I'll accept your answer since it's throughly researched. Thanks! –  Traveling Tech Guy Apr 8 '13 at 19:54
    
→ Guy: if you identify the sound file, you'll be able to find the originating app.. Please inform us of your results ;). –  daniel Azuelos Apr 9 '13 at 17:05

Could it be the sound a banner ad is playing? Try an adblocker to experiment. For example, if using Firefox, you can setup http://adblock.mozdev.org and see of you notice the sound still occurring or not.

I had a weird noise once that sound like a system sound, but eventually discovered that it was an ad that was appearing on alot of sites I visited.

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Nope. i'm using adblocker and ghostery in all my browsers –  Traveling Tech Guy Mar 11 '13 at 0:01

Since you did virus check ect.(and I do not think virus software has a sound file) >lets try:

  • check your Notification center and disable all sounds for each application

  • lets try to replicate the sound you hear, in System preferances > sound > sound effects, and play the highlighted one (it should say "build-in") to see if your system is responsible (those are system alert sounds).

  • While in here, disable the "play user interface sounds", to check if it is you making the sounds.

More drastic measures: Disable your internet connection, to see if the sound is triggered from outside.

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By "Notifications Center", I gather you're referring to OS 10.8. I'm on 10.7.5. The sound still occurs, but less frequently now... –  Traveling Tech Guy Mar 29 '13 at 17:46

Another possibility: If you use the Keychain Access program and unlock a keychain, it will automatically relock after a period of time, probably 15 minutes, and make this sound.

(Background: I was taken aback by this sound and began to search the web for this "shutter sound" phenomenon. Using @daniel Azuelos' excellent answer, I was able to confirm that what I heard was "lock" and put two and two together.)

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I figured out what it was on my PC. . its a camera.wav file in Google Chrome. It's used by some extension but I cannot figure out which one. do a search for camera.wav and you will find the file.

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First I thought if was related to a full trash can that would not empty! My computer has been making a un identified shutter sound for some time. I noticed it always went off when I opened Outlook mail or hit send and receive! As well as other times when I was not pointing at anything with my mouse. It was disturbing! Today I sought an apple professional and it was found to be a sound produced by Outlook. If you have Outlook on your Mac and this sound annoys you here is how to fix: Go to Outlook - click preferences - click notifications and sounds under sounds default untick "No new messages"

Peace at last! Thanks to Aaron from Apple!

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