Constant high-pitched humming, buzzing, whining

[kaynemcgladrey]

Hi,

There is a high-pitched continuous humming/buzzing/whining/noise in all recordings produced with Audacity or other software on my MacBook Pro. I am attempting to produce online training materials and would like to use Audacity 1.3.8 to record the audio portions of the content. After much research online I am posting a sample with the specific problem that I have. Hopefully, a semi/professional audio engineer can help me.

The problem is that when I use 'noise removal' it does not remove the noise from parts where I am speaking. I suspect there's some Nyquist script / ground loop / sound engineer voodoo required to remove this sound. It makes the recordings unusable.

http://audacity-noise.s3.amazonaws.com/noise.zip

The attached recording was produced using a MacBook Pro, a Griffin iMic, and a Rode VideoMic.

Hardware I've tried:
Griffin iMic with cheap wired headset
Line-in port on MacBook Pro with Rode VideoMic
Line-in port on MacBook Pro with cheap wired headset
Built-in microphone on MacBook Pro
Microphone on Canon Elura (videocamera) attached via Firewire to MacBook Pro

Techniques I've tried
Unplugging MacBook Pro from power while recording
Keeping MacBook Pro on power while recording
Shutting off cell phone while recording
Touching MacBook Pro while recording
Moving microphone three feet away from MacBook Pro while recording (note: does not apply to built-in microphone scenario)

In all cases, the sound heard for five seconds at the beginning of the recording is present in all recordings. I have settled on the Rode VideoMic with Griffin iMic as they produce the richest, highest quality sample. However, they still have the noise.

I strongly suspect the MacBook at this point. However, I do not have a second computer to test this with, nor is that a valid workaround as I cannot produce days of technical training on a friend's or colleague's borrowed laptop.

I do not believe at this time that I can purchase a pre-amp or other external device.

I cannot absolutely remove this sound using the built-in noise reduction effect in Audacity.

Moving the sliders all the way to the left does not remove the noise.

Moving the sliders all the way to the right removes the noise in the quiet parts. However, the noise is still present when I am speaking.

Please help.

[kozikowski]

The first thing we need to deal with is the Version. You mention Audacity 1.3 and yet you posted in the Audacity 1.2 forum which is it?

If you're using Audacity 1.2, you probably shouldn't be. If you have an Intel Mac with Leopard (OS-X 10.5) there is no stable Audacity 1.2. The only production version for us is Audacity 1.3.

Which in itself is not a simple answer. I personally am still using 1.3.7 available here...

http://audacity.googlecode.com/files/au ... -1.3.7.zip

But the latest version is 1.3.8 available from here...

http://audacityteam.org/download/beta_mac

But because of birthing pains on the Mac, we are urged to send the users to the latest 1.3.8 Nightly Build from here...

http://forum.audacityteam.org/viewtopic ... 37&t=11534

Are you following all this? Use the 1.3.7 version until the final 1.3.8 is working.

You will find that the noise reducer in 1.3 is light years better than the one in 1.2. When I get a second, I'll pull your sound file down and listen to it.

Koz

[kozikowski]

Sorry. One more. This isn't complicated enough yet.

http://forum.audacityteam.org/viewtopic ... =10#p34670

Koz

[kaynemcgladrey]

If this post needs to be moved I don't know how.

Here's the build information (About Audacity - Build Information)

Build Information

File Format Support
libmad
(MP3 Importing)
Enabled
libvorbis
(Ogg Vorbis Import and Export)
Enabled
libid3tag
(ID3 tag support)
Enabled
libflac
(FLAC import and export)
Enabled
libtwolame
(MP2 export)
Enabled
QuickTime
(Import via QuickTime)
Enabled
Core Libraries
libresample
(Sample rate conversion)
Enabled
PortAudio
(Audio playback and recording)
v19
wxWidgets 2.8.10
(Unicode)
Features
Nyquist
(Plug-in support)
Enabled
LADSPA
(Plug-in support)
Enabled
Vamp
(Plug-in support)
Enabled
Audio Units
(Plug-in support)
Enabled
PortMixer
(Sound card mixer support)
Enabled
SoundTouch
(Pitch and Tempo Change support)
Enabled
Build Information
Program build date:
Jul 15 2009
Build type:
Release build
Installation Prefix:
/usr/local/
Settings folder:
/Users/kaynemcgladrey/Library/Application Support/audacity


--
And here's the Audio Device Info (Help - Audio Device Info)

==============================
Default capture device number: 3
Default playback device number: 2
==============================
Device ID: 0
Device name: Core Audio: Built-in Microphone
Input channels: 2
Output channels: 0
Low Input Latency: 0.001088
Low Output Latency: 0.010000
High Input Latency: 0.010884
High Output Latency: 0.100000
Supported Rates:
==============================
Device ID: 1
Device name: Core Audio: Built-in Input
Input channels: 2
Output channels: 0
Low Input Latency: 0.001088
Low Output Latency: 0.010000
High Input Latency: 0.010884
High Output Latency: 0.100000
Supported Rates:
==============================
Device ID: 2
Device name: Core Audio: Built-in Output
Input channels: 0
Output channels: 2
Low Input Latency: 0.010000
Low Output Latency: 0.001088
High Input Latency: 0.100000
High Output Latency: 0.010884
Supported Rates:
8000
9600
11025
12000
15000
16000
22050
24000
32000
44100
48000
88200
96000
192000
==============================
Device ID: 3
Device name: Core Audio: iMic USB audio system
Input channels: 2
Output channels: 2
Low Input Latency: 0.010000
Low Output Latency: 0.003061
High Input Latency: 0.100000
High Output Latency: 0.030612
Supported Rates:
8000
9600
11025
12000
15000
16000
22050
24000
32000
44100
48000
88200
96000
192000
==============================
Selected capture device: 3 - Core Audio: iMic USB audio system
Selected playback device: 2 - Core Audio: Built-in Output
Supported Rates:
8000
9600
11025
12000
15000
16000
22050
24000
32000
44100
48000
88200
96000
192000
Unable to open Portmixer

[kozikowski]

That's OK. Leave it here. And please don't post pages and pages of diagnostics unless we ask for it. The forum isn't that big. The hamsters in the back room have a hard time keeping up.

The sample sound that I got was roughly 50 times lower in volume than it should be. That's about -30dB on good, energetic peaks. Yes, you should not be peak clipping at zero during live capture, but you shouldn't be too low, either. As good as it is, the Mac Analog Line-In does have quiet noise and it's good to stay away from it.

So all you need to do is capture the work about 20dB hotter and that should do it. The background noise will go down by over half (to your ears), and since it's already very low, should kill it completely. If you insist on monitoring with the volume up to scaring the cat, then the Audacity 1.3.7 noise reduction should take care of what's left. In my opinion, easily.

The Griffin iMic does not have a good reputation. Mine is in a dusty box in the garage. In my system, I could hear the hard drive spinning up and searching. eeeeeEEEEEE Click Click Click behind every capture.

Koz

[kozikowski]

What are your Audacity Preferences set to? Numbers like 44100, 16-bit, Stereo?
Koz

[kaynemcgladrey]

Audacity preferences set to 48000 stereo.

If I use the line-in with any microphone I own I get an endless stream of complaints from my colleagues. I have in fact tried yelling entire training sessions into a microphone attached to the line-in and heard, "yes, content's fine, but you're too quiet".

The sample was recorded in a normal speaking voice using the iMic and Rode VideoMic.

I have had this issue in every recording application I've tried.

My plan of record was to remove the noise from the recordings and then to increase the volume.

Please explain how I get "about 20db hotter".

[kozikowski]

This test clip was recorded on my bed to get the echo reduction and with a very old ribbon microphone into a small pro field sound mixer and directly into my PowerBook Line-In.

http://www.kozco.com/tech/LRMonoPhaset4.wav

The only production that was done to it is the muting left and right and the oddball phase reversal in segment four. No noise reduction. It was recorded much hotter than your test clip, but still safe from overload. I do this all the time in movie production (not with my voice, obviously).

Forget Audacity for a minute.

Apple > System Preferences > Hardware > Sound > Input.

Is that volume control slider all the way up? You do get the bouncing blue patches when you speak, but can you do anything to make the far right-hand one light up? That's the damage light from too much. I'm betting no. I can easily fill up that whole sound meter by making the field mixer too hot.

It may be time to put the iMic in the garage next to mine. We did a review of sound cards. You should look that over.

http://forum.audacityteam.org/viewtopic.php?f=27&t=9477

I'm going to go down the model numbers you gave us, but for the moment I need to leave.

Koz

[kaynemcgladrey]

http://audacity-noise.s3.amazonaws.com/noise2.zip

Moved the slider all the way to the right (Apple > System Preferences > Hardware > Sound > Input).

Makes me louder, but also drastically increases the volume of the buzzing. I'd previously turned that down as it made the buzzing less prevalent.

I'm reading your statement "small pro field sound mixer" as "you need another piece of equipment that will cost money". Similarly, "We did a review of sound cards" makes me think that you're recommending I not use the onboard processing on the MacBook Pro but move that to an external. As this is not a personal project but a work project I just can't go out and buy something without justification.

[kaynemcgladrey]

Spoke with one of my colleagues. He used a Plantronics 750 headset and his MacBook Pro and had no such difficulties with the high-pitched buzzing.

As he is currently unable to send me his headset I returned the iMic and purchased a Plantronics 777 gaming headset.

The high-pitched buzz is now a low-pitched hum. This is now my fourth input method.

http://audacity-noise.s3.amazonaws.com/ ... amples.zip

Enclosed are samples from both 50% and 100% in System Preferences - Sound - Input - "Unknown USB device". This headset supposedly has a noise canceling feature.

In both samples, if I take a noise profile of the first five second and then try either minimum, maximum, or halfway noise reduction I hear noise on some letters and sounds. "ed", as in "recorded" is one place where the buzzing shows up.

A local Apple retail expert - at the shop where I returned the iMic - said he hadn't heard of anything this weird before.