There's a Mac audio bug that may have existed for more than 20 years

The bug concerns how the left/right stereo balance can wander on Macs when listening under headphones. AppleInsider readers first reported the same issue — back in 2002.

Now it's been brought back into the spotlight by a developer known on X/Twitter as Fabian.

The app referred to as solving the issue is Balance Lock by Tunabelly Software. Released in August 2015, it has had only five updates since, with the most recent in May 2021.

It does appear to be the same bug that was reported on AppleInsider in late December 22 years ago. "I am experiencing problems with sound balance," a reader in the forums, who said they were using an iBook.

"Whenever I plug in earphones or headphones, the sound balance either tips to the left or the right and how much also differs," continued the report. "I have to always adjust the balance manually in the sound prefpane."

Another AppleInsider reader said they had first noticed it after updating OS X to version 10.2.3. That's Mac OS X Jaguar, which was released on December 19, 2002.

Developer Fabian's tweet has now also been followed on Hacker News by a thread discussing multiple audio problems with Macs. Many of those concern crackling sounds, with one reader noting that "I have 4 external all different sound cards and amps (USB), it's the same on all of them."

"I also didn't realize that this problem was common," wrote another, "but I switched to using an optical toslink cable to an external DAC which seems to have fixed it for me."

"I have found a strong correlation between memory pressure and audio glitches with my external DAC," responded a further reader. "I filed a bug on this over two years ago and it has gotten no traction."

Several Hacker News readers note that issues including the the left/right balance bug can be fixed by using Rogue Amoeba's SoundSource app.

Apple is aware of the issue

Apple hasn't commented on the new report, but as spotted by MacRumors, in 2012 it did release — and later remove — a support document addressing the issue.

"In some cases the audio balance may unexpectedly drift towards the left or right channel," it said. "This can happen if you rapidly press the volume up or down keys while the computer's microprocessor is under heavy load."

Its solution was particularly unhelpful. Apple told users to go to the system audio settings and manually "drag the audio balance slider to the desired position."

Unfortunately, that option no longer exists in macOS Sonoma. That's probably because rather than allowing listeners to fiddle with stereo, Apple Music has been moving to spatial audio as quickly as it can.

Today while listening to music over headphones, the balance can shift intentionally so that a singer, for instance, appears to be in a fixed position as a listener turns their head.