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Audio Noise and Distortion

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andrew spano
Audio Noise and Distortion
on May 31, 2014 at 11:26:15 am

I'm a stand up comedian and recorded a set last night using a clip-on microphone. The audio came out distorted at certain parts because either the microphone was rubbing against my shirt or I was speaking to loud. In any event, I was wondering if there was ANY chance of salvaging it. The link below is a 7 second sample of what I'm talking about. Any information, as always, is greatly appreciated. I've used this forum for years and you guys have always been helpful. Thanks much.

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Mark Suszko
Re: Audio Noise and Distortion
on Jun 2, 2014 at 3:03:47 pm
Last Edited By Mark Suszko on Jun 2, 2014 at 3:09:22 pm

IMO, that's not rubbing the mic, that's over-driven (too loud) audio, and once you distort like that, there's not much you can do to fix it. You *could* try to use a parametric equalizer to reduce the deeper parts of the distorted segments. Or a notch filter, which will pass everything above a set (low) frequency. This doesn't repair the distorted section, but might help with the *apparent* clarity of those parts, making them seem less harsh.

Moving forward, the audio recording system you use needs a better automatic gain control, one that reacts faster to dynamic level changes. Or, the mic you use is wrong for your style.

Here's the thing: the conventional "stick" mic that is hand-held or mounted on a floor stand, the more or less standard stage mic used for vocals in bands and for stand up public address, is most often what's called a dynamic cardioid type mic. The workhorse mic in this area is the Shure SM-58. It's as common as fake brick walls in 80's comedy clubs.

The dynamic mic mechanically converts sound pressure into varying voltage that becomes amplified and then projected on speakers or recorded, and besides being rugged enough to drive nails with, they are hard to "blow out" by the subject being too loud.

The "cardioid" part refers to the mic's pickup pattern, and means it grabs sound best inside a pattern resembling a drawing of a valentine heart: strong response directly ahead, somewhat tapering response on the side lobes, nothing behind, where the cord comes out. A directional mic picks up only what's directly in front, rejecting a lot of what's on the sides. That would be hard for you to use unless you stood really still like, I dunno, Steven Wright, maybe. An Omni mic picks up equally in every direction except the rear where the cable comes out. You can move around the mic, vary position and distance, or have two people share it, and it's all good. The downside of the omni is it can bring in extra noises you didn't want: hecklers, the kitchen, glasses clinking offstage, things like that.

How this relates to you on stage is, you gotta know your tools, because you vary your mic handling technique, depending on the mic's pickup pattern. Different types have wildly varying performance characteristics. And you vary your technique, depending on if the mic is dynamic, or if it is powered, what's sometimes known as a "condenser" mic. A great example of mic-handling is the old Cosby "Noah" routine, where he "eats the mic", over-driving it and distorting on purpose, to simulate the "Voice of God". Eating the mic also deepens your voice from something they call "proximity effect", where deeper sounds get more emphasis in the mic when you're working it super-close to the mouth.

Condenser mics are way more sensitive because there's a very sensitive transducing element and an amplifying circuit built right inside the mic itself, and they are easily over-driven by too much SPL (sound pressure level). The sample clip you put up sounds to me like either you used the wrong technique with a powered, condenser type mic, and over-drove it on the loudest parts, or your mic was right, but too close, and/or the recording system didn't have the headroom or dynamic range to deal with the very high sound level in the short, loud parts. Recorders and PA's often have automatic level control circuits that try to 'ride the gain", automatically making soft sounds louder and loud sounds softer, aiming for a mushy middle-ground. But their reaction times can sometimes be too slow for explosive sounds.

Using the condenser, you have to limit your vocal dynamics, because while it grabs a stage whisper really well, when you wanna yell like Sam Kinnison, you either have to back 'way off from the mic, or tip it away from your mouth to present the less-sensitive edge of the pickup pattern, or "stage yell", without actually projecting too much.

Clip-on or Lavaliere type mics, like what you say you wore, are often condenser-type mics, and almost always omni-directional; you have to go out of your way to find directional ones. You can identify if it's a condenser mic if it contains a small battery compartment in it somewhere, or uses what's called "phantom power" coming in thru the mic cable from the mixer. A power on-off switch is another sometimes but not always reliable clue it's a condenser mic.

What I see done more and more often, (and the BBC guys seemed to do this first) is to put the lav mic on with the mic's head facing down at your shoes, not up towards your face. Yes, that sounds counter-intuitive, and yes, it does reduce the mic's overall level a *little* bit.

But what you get by pointing it away from the face and towards your shoes, is that it can't pick up distortions from your breathing, or from the plosive B and p sounds that can "pop" loudly and be distracting and hard to get out. It may pick up a little more sound from the first row, if you work at the extreme front edge of a stage, but overall, it's a cleaner technique that lets you really yell more loudly, and suddenly, without blowing-out your levels as much.

Closely check your mic before a show and learn to recognize their characteristics, and your audio will immediately improve.

And if you're wearing one of those flesh-colored boom mics, I don't wanna know you; I hate looking at those things on a stage or an event. They belong on phone operators, airline pilots and exercise instructors, in my opinion. Not on a stage.

I hope that helped. Doing a good ten minute stand-up set, just once in my life, is one of my "bucket list" items, but I have a little stage fright in live scenarios, so I greatly respect anybody that can do standup on a regular basis. Good luck!

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andrew spano
Re: Audio Noise and Distortion
on Jun 5, 2014 at 1:28:57 am

Wow. Thank you so very much. I will take your advice and apply it.

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