I’m seeing random glitches popping up at intervals on the LEFT channel only during my recording sessions. These glitches can be seen in the waveform and also heard on playback. They intermittently come and go. I have attached a sample waveform to illustrate. Do these glitches look familiar to anyone?
My system setup is as follows
Audacity: Version 2.4.2
Dell latitude laptop
OS: Windows7 Home Premium
Type : 32-bit
Processor: Intel 2.5GHz
Audio Interface: Steinburg UR22 USB Audio Interface, 24bit/192KHz
Microphone : Audio Technica AT875R w/pop filter - Connected via XLR cable to left channel
That doesn’t look like anything I’ve ever seen before.
I’m a little lost about the display. That’s a recording and one copy, right? They appear to be the same thing.
Drag-select and File > Export one of those as WAV (Microsoft) 16-bit and post it here on the forum. Scroll down from a forum text window > Attachments > Add Files.
We need to be able to analyze it in detail. Since you have two of them, you’ll have to work with only one and File > Export > Export Selected Audio. If you don’t do that, the Export will try to add the two of them up and distort the waves.
If, after swapping the left and right mics (including leads), the noise still occurs in the left channel, then it’s not likely to be due to the mic or lead.
Also, if you look closely to the waveform of the interference, you can see that it is some kind of “digital” noise, so very unlikely to be due to the mics or mic leads.
The timings are approximate, but certainly show that it is almost 100% data interference.
The question now remains, what is causing it?
Thinking about it further, here are some possible causes:
The USB cable is dodgy.
By this, I don’t mean the connectors, I’m referring to the conductors and/or shielding that are sub-standard.
I have come across some really horrible low cost ones and that can lead to data corruption (BTW same applies to HDMI).
The driver is playing up or needs updating.
The USB audio interface needs more current.
USB low speed peripherals have 100mA @5V available as soon as they are connected.
If they require more, they have to request it.
There is a prescribed protocol/sequence for this occurrence.
Perhaps, this is what it is, the interface for some reason or another, needs more than 100mA and is requesting it.
The data back and forth from this request may somehow be landing up as part of your audio data.
Are you going through a USB hub or other splitter? Can you try another USB connection?
Can you hear that in the Steinberg headphone connection? Turn MIX all the way to INPUT and turn the headphone control all the way up. If you hear it there, then the Steinberg is in trouble.
How many microphones do you really have? Are you wearing a headset instead of headphones? Do you have a Web Cam connected? Any wireless stuff? Counting the laptop, that can be up to six microphones right there. My laptop has dual built-ins.
Scratch everything. Start a recording and gently scratch the microphones.
You’ve got to approach this systematically. Rather like finding a fault in a car. In this case is it hardware or software. A visual check of all inputs and outputs and cables, and as a matter of good maintenance give them a clean, would establish this one way or the other.
Could it be the sound card acting up. I personally shut everything down as much as possible via task manager to free up resources before loading a file into audacity.
Another thing I turn off / down is System Sounds while working with Audacity.