iMac audio "hiss" starts and stops for no reason?

An audio "hiss" starts and stops in my iMac for no reason?

While I am working in FINDER dragging jpeg files or pages files, my SPEAKERS come on frequently and produce a "hiss." The "hiss" lasts from 10 seconds to 90 seconds.

NOTE: the VOLUME CONTROL has no effect on the quiet "hiss." I raise and lower the VOLUME and the "hiss" volume remains the same.

When I turn DICTATION on , the "hiss" sound begins immediately, I also noticed that DICTATION no longer works? The bouncing microphone icon is showing a signal is being heard, but no text is being added as I speak.

While DICTATION is on, the "hiss" soon stops. And when I turn DICTATION off, the "hiss" sound immediately STARTS again and lasts maybe 30 seconds.

I just opened FINDER and it caused the "hiss" to begin. It lasted 20 seconds. Then I highlighted a jpeg file, and the "hiss" started again. Nice, huh? Rebooting does not solve this problem.

Can someone please help me help me get rid of this "hiss?"

Thanks,

Sir_Viver

Hmm what Mac and what operatingnsystem. Snakes in the pit?


http://www.mac-forums.com/forums/news-community-announcements/313284-writing-quality-post.html

Sounds VERY much like a digital/analog detection problem in the jack.

Intermittent AUDIO HISS for no reason

SYSTEM: 21.5" iMac, 2.7 GHz Intel Core i5 with OS X 10.9.4

Hi Chas_m:

You wrote, "Sounds VERY much like a digital/analog detection problem in the jack."

YES! YES! YES! I think you may have identified my problem! How in the world did you suspect the jack?

Today I plugged in my headphones, and 1. They DID NOT WORK (no sound). And in the headphones I heard a very quiet, low frequency "fluttering" sound that is not controlled by the volume or MUTE controls. and 2. Insertion of the headphones DOES NOT turn "OFF" the iMac's internal speakers!

So, should I conclude I have a hardware problem (the jack)? or could this be a software problem too? Remember, when I open or close any kind of file, the "hiss" noise begins, and then it goes "off" in 5 or 10 seconds. In addition, my dictation software no longer works, but the bouncing mic icon shows the detection of my voice.

It looks like I'll need to take my iMac in for a repair, but I am impoverished and seriously ill, so I need this like a hole in the head.

Can you or anyone else add MORE to this discussion? Thank you for your excellent analysis!......Mike, 66, in Winston-Salem, NC

Before you take your iMac in for repair, try plugging and unplugging your Mic several times to see if you can get the jack working again. This is a common problem by the way. It also happens on the MacBook and MacBook Pro. Unless your iMac is still under warranty, you may be taken back by how much repairing the Mic jack will cost. Apple usually recommends replacing the entire logic board since the jack assembly is surface mounted to the board.