no noise

July 22, 2009 9:04 PM

Macbook pro sound problem. Some sounds only heard through headphones.

On my macbook pro (early 2008 model), the sound generally works fine, both through the built in speakers and through headphones. However, when I tried to run certain programs, I can only hear their sound output if I have headphones plugged in (while other sounds still function normally).

The programs were the white/pink noise generators noise and noisy. I was just mucking about with them, but now I am curious as to what is going on.

Can anyone help to explain what could be causing this? The likely candidate is that I did have a trial of Audio Hijack Pro installed, but I removed it when it screwed up Skype. I am using the latest version of Leopard.

posted by theyexpectresults to computers & internet (6 comments total)

That actually happened to me a few months ago. There was a red light coming out of the headphone jack too; I didn't even know there was a light in there but I think it indicates the sound won't play without headphones. The thing that somehow pulled my computer through it was starting it without headphones plugged in, and then trying to play something.
If not that, I don't know. Macs are mysterious.
Needless to say, you're not alone, at least.
posted by lhude sing cuccu at 10:29 PM on July 22

Yeah, happens every now and then to me, same computer (early 2008 MacBook Pro).

I think it's an issue with the jack; it's a multi-purpose jack that can take the traditional metal headphone plug, or an optical TOSLINK plug for digital connections. In any case, when inserting or removing my headphones, for whatever reason the MacBook seems to think I'm using a TOSLINK cable and switches to digital (optical) mode. Sticking the plug in and out a few times seems to clear it up.
posted by bhayes82 at 10:57 PM on July 22

lhude sing cuccu, that red light is actually the TOSLINK (optical) signal. It's used in conjunction with a special cable to transmit a high-quality, digital signal.

To answer the actual question: is it possible that those programs were intentionally designed like that? Have you checked Audio MIDI Setup (under Applications>Utilities) when the program was running? What did it list as the output device?
posted by wsp at 11:19 PM on July 22

Er, what I meant to say was: It's a high quality, digital signal that is transmitted via a special cable. Here's the Wikipedia article, if you're curious.
posted by wsp at 11:22 PM on July 22

Seen that with a couple of apps - including, IIRC, one of the Apple Developer demo/sample apps. Somebody seems to have made an updated build of Noisy.

Looking at the patch posted in that thread, it seems to be related to incorrectly/incompletely initialising the audio device through CoreAudio.
posted by Pinback at 12:45 AM on July 23

Thanks a lot Pinback. The new build seems to work as expected.
posted by theyexpectresults at 12:54 AM on July 25