After the honeymoon was over, and I started using the iPhone 3G S in earnest, I began to hear a high-pitched noise on my iPhone-recorded videos. At first I thought it was the environment, background noise, or just plain interference. However, once aware of the noise, I noticed it anytime the phone was recording audio, such as with voice memos. The whine is actually emitted by the speaker, and then becomes part of the recording. You will usually only hear it in quiet recordings.
Fortunately I know one of the best AV guys in the industry, Matt Kappenman, who analyzed and isolated the sound for me. He told me that, “It’s right around 4400-4500 Hertz, which is a C# for those musically inclined.” I’m not so musically inclined.
Here is a sample video file we recorded in a quiet room (actually put it inside a safe):
And here we take a short video of Tova, our dog:
And here is the file for which Matt was so kind to isolate the noise: MP3 (128KB)
How to Reproduce the Problem
- Ensure that you are in an otherwise silent environment
- Launch Camera.app
- Switch to video recording mode
- Insure that the speaker volume is turned up to maximum
- Record a short movie
- Stop the movie recording
- Play the movie recording back
Note the high-pitched whine that is clearly audible during the course of the movie (you may have to turn your volume up a little). You can hear this while recording if you stick your ear by the speaker at the bottom of the iPhone. The volume of the whine is directly correlated to the volume of the iPhone 3G S speakers during the movie recording — higher volume results in louder whine.
The whine seems to only come from the built-in iPhone speakers (located on the bottom of the phone). If you plug in ordinary stereo headphones to the iPhone, the whine is not audible in the headphones during recording, even with volume turned to maximum.
So far we’ve been able to reproduce the problem 100 percent of the time, with all known iPhone 3G S phones we can get our hands on. However, due to hearing ranges, some people simply can’t hear the noise while others in the room can.
Incidentally, others are reporting this same high-pitched noise when SMS messages come in or when the phone locks. While those problems are annoying, the video recording whine actually interferes with the quality of the video.
The Cause and Solution
The exact cause is unclear. It could be software or it could be hardware. The problem does not appear to occur on the iPhone 3G during Voice Memos, so it appears isolated to the iPhone 3G S. We also verified that it occurs in Airplane Mode, thus ruling out network-related problems. Even if it is hardware, Apple may try to patch the problem in the audio recording routines.
The short-term workaround is easy enough; people might just learn to live with it. Either use headphones while recording or manually place the iPhone into “silent” mode prior to starting the video recording, by moving the ring selector to vibrate.
Here is Tova without the whine using the solution:
Matt tells me that with Audacity, or another audio program, you should be able to isolate and remove the sound if it’s present in your recordings.
Is it just some 3G S iPhones or all of them? Try to reproduce the problem and let us know your experience in the comments.