Help with audio quality

[lberman]

HI guys,
I am new to this forum but have found lots of useful info, so thanks!
Hoping you can help me....I am a voice actor who uses Audacity to record auditions. I have an Audio Technica USB mic that I use to record. Pretty simple sound chain. I'm recording in a walk in closet. My guess is I can probably soundproof the room a bit better with some more blankets, etc. but there seems to be a very low noise that runs through each of my recordings. It's not the computer b/c I'm using a MacBook Pro (which is pretty quiet anyway) but is also in a different room (my USB cord is long enough to do that) I shut the door from the closet where the mic is to the room where the computer is..someone mentioned that perhaps it was my USB cord that was causing the noise ? Or is it something else? I am attaching a link to a recent audition so you can listen.

http://www.box.net/shared/hzoqca1c4m

Would love to figure this out. Also you'll note there are some "mouth clicks" --the mic is clearly sensitive and I'm not sure what I can do about that but maybe if we can figure out the background noise we can move to that next. Maybe it has something to do with the levels I'm recording at? I have to admit I am kind of clueless when it comes to setting these levels and making sure the db levels are above/below a certain point, so feel free to point me in the right direction with that, too.

Thanks so much guys. Appreciate any advice/insight you can offer. I'm not the most technical girl on the block but I'm working on it

[kozikowski]

AT2020? Which model number?

You don't stop talking long enough for us to hear and analyze the background noise. Yes, there is something back there.

Count to five in normal voice and then hold your breath for two or three seconds.

That's high frequency distortion -- "essing" and it's a little rough to suppress in post production. I couldn't get rid of it with gentle equalization or tricks without turning the rest of the presentation into mud.

The instructions (if that's the correct microphone) don't go into quality of sound at all. It's a typical Audio Technica "Good For Everything that Ails You" ad. It may be just a bad combination. You have a crisp voice and the mic boosts crispness because everybody thinks that sounds terrific.

Not always.

Let's see what the other elves think.

One of the problems with a USB microphone is the construction -- everything is built-in and you can't change it. But the over crispness does bother me. Are you talking into the right face of the mic? It's a side-fire and there is a serious bias to accepting sound only from the front (cardioid).

Which Mac have you got? I got a solid-state drive with my MacBook Pro and it's quiet enough to get a good recording with the built-in microphone. I did a test once -- somewhere..

Koz

[steve]

Two things that bother me:
1) The very low frequency rumble that keeps coming in (look closely at the waveform right at the beginning of the track)
2) The noise level is not constant - it's going up and down all over the place. Notice the sudden rise in noise level just before the first word - what's going on there?

As Koz said, it's probably worth experimenting with microphone positioning.
Are you using a pop-shield (thin fabric screen between voice and microphone? If not it would probably be worth getting one or making one (nylon tights stretched over a wire coat hanger work well). There is little in the way of "popping", but you may be compromising your microphone placement in order to avoid blowing on the microphone. Having the option of a pop-shield will allow more flexibility with microphone placements without having to worry about popping (wind blast from your breath).

[kozikowski]

This is my Macbook cold except for the heavy cloth (Duvetyne) over the screen to avoid sound reflections.

http://www.kozco.com/tech/audacity/clip ... Test2a.wav

I ran a very gentle noise reduction and pulled much of that air conditioning noise out.

http://www.kozco.com/tech/audacity/clip ... emoval.wav


I think the performer's microphone is broken or just not up to the job. Still, it's $150 USD, so it's not particularly cheap. I think I would also try pulling and replugging the USB connection two or three times. If AT went the cheap route and is trying to run everything from 5V, any USB problem at all will cause problems.

Koz

[kozikowski]

Oh, wait. This is running on a USB extension cable, isn't it?

See what happens to the noise if you take the extension out.

Koz

[kozikowski]

Behold, another of the problems of a USB microphone. 2M/six foot cable restriction.
Koz

[steve]

I have an Audio Technica USB mic

Do you have the model number?

[kozikowski]

All the Google hits go straight to the AT2020. This may be like the Logitech Desktop Microphone which doesn't have a model number because there ever was only one.

Koz

[lberman]

Hi,
Thanks to all for their replies so far,
Yes, model number is 2020. Sorry I didn't include that in the original post.
I do have a pop filter. Perhaps I need to work on positioning the mic...
The sound I am most concerned with (as a previous person responded on) is that underlying noise/hum throughout the recording.You can see it at the beginning in the waveform and it runs throughout. I am not using a USB extension cord --my cord is just long enough that it allows me to shut the door of the closet yet keep the computer in the other room. I wonder if I am squeezing the cord when I shut the door and if perhaps that's causing the noise? I am going to experiment a bit today. Can USB cords just break or wear out? Perhaps it's worth trying to pick up a new cord?

I will say that I ran audacity's noise removal and that helped tremendously. I downloaded the new beta version and it made a huge difference. I'll actually post the new recording when I have a moment. But, I'd really like to figure out the source of the problem, vs running the noise removal feature on each audition in the future. There's gotta be an answer.
I don't think it's that cheap of a mic.....I mean, it is certainly not top of the line quality, but it gets great reviews, so I should be able to record a clean audition with it, esp with my MacBook Pro.

Thanks again,
Lori

[steve]

Thanks for the extra information. There are 3 models of Audio Technica USB mic that I can see, and the AT2020 is the top of their range.
Interesting to note that it has a headphone socket built in, which solves the old problem of being unable to monitor the live recording without an echo. This feature is thankfully becoming a lot more common.

Yes the Audacity Noise Removal effect works well with this type (and level) of noise.
I would recommend running the "High-Pass Filter" effect before using the Noise removal effect.
A high pass filter allows high frequencies to pass through unchanged, but blocks frequencies below the "Threshold" setting.
As your voice is not particularly deep I'd recommend setting the high-pass filter to 100 Hz and 6 dB per octave. This will eliminate that very low frequency waveform that I mentioned earlier. However, there is another issue that it will make more apparent.

The very first word in the sample is a lot louder (higher peak amplitude) than the rest, and has almost clipped at the top edge. If you zoom in and look carefully at the waveform you will see that the waveform has been significantly flattened at the top.

peak-limit.png (3.18 KiB) Viewed 2170 times

It has not been cut off flat at the top, but has been severely squashed at the top which indicates that the input sound has exceeded the capability of the microphone (too loud). Fortunately the microphone has handled the overload quite gracefully and the distortion is not too noticeable in the sound, however, when you apply the high pass filter you will notice that these peaks get higher and will be above 0 dB. You will need to use the "Amplify" effect on the entire track to bring the peak level back down to 0 dB (Use "Effect > Amplify" with the default settings).

Before going further, was the recording made as one, unedited take or have you edited/processed it in any way?