Eliminate Noise in Your Voice Over Recordings

Noisy recording

Eliminate Noise from your Voice Over Recordings

What is Noise in a Voice Over Recording?

Trying to define noise is like trying to define a “weed”.  A rose can be a weed in a vegetable garden.  Many a lawn-care expert spends much energy defeating the dreaded dandelion and yet it is one of children’s favorite flowers.

And so it is with “noise”.  Pop music may offend the ears of classical music listener and a loud television may be noisy to someone taking an afternoon nap.

But the definition of noise in a voice over recording is simple to define.  It is any sound in the recording that is not your voice. Let’s look at various sources for these spurious sounds and some hints at how to reduce them.

Electrical Noise – Hiss

When you talk to an audio engineer, this is the noise they are discussing.  These are the hisses and hums that are generated by the actual gear that you are using to record.  And in a well constructed recording system these just should not be there.

The most primitive type of electrical noise is hiss.  This can be caused by the random bouncing and bumping of electrons.  What does it sound like?  Well, if you’re old enough to remember the last century, you may recall the sound of a radio tuned between stations or a TV station that had signed off for the night.  But for you Milleniums here is an example:

 

The predominate cause of electrical hiss in your system is…  cheap gear.  Sorry.  I’ve found that with USB Mics if you spend less than $150 you’re going to get hiss.  This is also true about analog-to-usb interface boxes and in-line analog-to-usb converters.  You don’t have to break the bank, but the gear that’s over $150 seems to be designed with a bit more care to audio quality. If you have a chance test the gear before you buy it, do it.  If you hear the dreaded “frying bacon” sound in your recording, even faintly, step up a notch.

Very faint hiss may be tolerable since many pros are used to hearing it (like tape hiss in the good old days).

Electrical Noise – Hum

If you thought “hiss” was a bully, you don’t want to meet “hum” .  Also referred to as “60 cycle hum”.  This is the sound you get when you unplug the (analog) audio cable from your TV or DVD player to your receiver or stereo amplifer.  (or for you rockers out there, when you unplug the cord from your guitar and not your amp:  BZZZZZZZZZZZZZZZ ! )  It is a symptom of poorly wired equipment causing a “ground loop”.

Hum is an instant indication that your audio is not broadcast quality!

Here’s an example… you will instantly recognize the sound:

 

The two big causes for this are:

1) a broken audio cable (once again an analog cable, like an RCA connector or a phone plug).  Try swapping with a known-good cable until you find the culprit.

2) an actual ground loop, when your gear is plugged into different outlets.  You should use ONE power strip and have all your gear plugged into that strip.

Electrical Noise – Other Electrical Equipment

You can also pick up electrical signals from other electrical equipment.  Electric motors, air conditioners, fluorescent lights, etc. can all put electrical garbage in your power lines. Keep all your analog cables routed far away from any of these sources.  Use “balanced” cables when you can (the mic cables have “xlr” connectors).

Also don’t use a “dynamic” mic  use a “condenser” mic.  Dynamic mics have a coil of copper wire inside that just cries out to electrical garbage in the air to “feed me Seymour!!”

 How to Test Your System

Here’s how to test your system for these culprits.  Set your mic at a normal recording level (we call this a “nominal” level).  Make sure the room is very quiet (including your breathing…) and then record 20 seconds of silence.  THEN read about 20 seconds of copy.

Then listen back (with headphones if possible!) for these three bears of noise.  Pause and play the recording several times to be sure the noise is coming from the recording and not your system.  It should stop and start again.

Hiss should be a  shhhhhhhh sound.

Hum will be the annoying  bzzzzzzzzz sound.

Other electrical noise may come and go.  When the fridge kicks on or someone vacuums.  Sometimes this can be reduced by using an outlet on a different circuit.

I turned off the timeshare refrigerator on vacation once and forgot to turn it back on.

Don’t do that.

And Then There is Actual Audio Noise

A barking dog may not be fancy electrical noise but it still has no place in your voice over recording. Will define and describe audio noise in another article.

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7 Responses to Eliminate Noise in Your Voice Over Recordings

  1. Lori Moran says:

    Hi William-good article. I don’t get buzz in my recording, but I can hear it coming out of my studio monitors when I am outside the booth. My husband, who is an electrical engineer calls it spurious noise. We played hell figuring how to get rid of it as it was driving me nuts. It was a ground loop. I do have everything on one strip. We ended up plugging the speakers into a non grounded input. I am not sure I am saying that correctly. Meaning plugging the 3 pronged speaker plug into an adapter that only had two prongs into the strip. Does that make sense? Anyway, it did get rid of it. But sometimes, for whatever reason, I will still hear it slightly. I have good equipment and good cables….who knows.

    • Yes, chasing down a buzz can be frustrating. Your speakers can also pick up buzz from electrical noise in the mains. I have an office neighbor who switches on something every once and a while that causes a buzz. Hmmm… I wonder if I use a two prong adapter… As long as it’s not in the recording I can live with it. You can check this with headphones which isolate what you’re listening to so you only hear the recording. Thanks for reading! William

  2. Here my issue was solar panels! Our inverter generates a powerful 20kHz ‘whistle’ that gets into every part of an audio system. Only very young people (and cats) can hear it. but on a voice track it would be visible to any client whose engineer happened to glance at their spectrum analyser. You can download an excellent free plugin, SPAN, from Voxengo, if you want to check. An analyser also pinpoints hums from fridges, computer fans etc. Could help you pick a better outlet socket, too, on Williams’s point. Ears are great, but visible measurement speeds up fixing the issue.

    I did this: lifted all mains grounds except the one to the computer. Put a four-foot spike into the garden to provide an alternative clean system ground. now there’s much less whistle and general supply line noise. Important safety point (picking up on Lori’s post) : if mains (plug) grounds are lifted, they can be kept in reserve by reconnecting through high-current bridge rectifiers. These will act as insulators unless a fault voltage develops. So you get a ’two-prong’ connection, but if something shorts, they will trip your supply/blow the fuse rather than see you injured. This method of grounding also removes the type of hummy ground loop that can arise from coupling up equipment that’s fed from the wall. There’s info on Google, but take care!

    My last vestige of that solar whistle is taken out with low-pass filter before sending off tracks. Rolling them off at 15kHz does no harm at all – that’s quality FM specification.

    • I would probably get a qualified electrician involved so you don’t inadvertently defeat the purpose of grounding the electrical supply in the house and defeat your ground fault circuit interrupters or something scary like that. I rather have a high frequency hum than electrocute myself. All this is probably way above the “pay grade” of the typical home brew voice talent. But an interesting problem and solution.

  3. Jim Buchanan says:

    As they say, only 10% of being a successful VO talent has to do with your voice. The rest is audio quality, executing the read as per what is in the head of the producer and effective marketing and networking. The rule is anything under -60db is OK for room or floor noise. And normalization should be -3db. Keep in mind, minus any “electrical issue” causing buss or hiss, other factors like floor noise (a totally quiet room, booth or surrounding) and room reflectivity are also major factors to having a clean sound. You may have the best mic and have “nailed” the read…but…a producer will pass to the next audition if the audio is “dirty”. If you have floor noise above -60 db, I recommend applying a noise reduction filter normally found on any audio software. Then, normalize to -3db. Doesn’t hurt to add a “little” dash of compression to make the VO audition sound louder without exceeding -3db.

    • Jim, you’re correct. The quality of your recording is probably the FIRST thing a client listens to, before your performance or your voice. They assume the job will sound like the audition if you’re recording at home. Nowadays your auditions have to be broadcast quality. Noise reduction only works on steady-state sound like hiss or hum. If you have that, you should identify the problem and eliminate it rather than depending on noise reduction. Too much noise reduction can add a “phasing” or “comb filter” sound to your voice. Also I agree that the first challenge you should attack is to make your recording space as “dead” as possible and eliminate extraneous sounds such as room echo, computer fans, air conditioner hum, leaf blowers and trash trucks, the kids playing Guitar Hero or Call of Duty…

  4. Jim Buchanan says:

    William. Yes. I agree on going overboard with applying noise reduction. One does risk the phasing or comb filter sound you refer to if there is a lot of bad sound to take out. Fortunately for me I’m usually around -55 or lower for “floor noise” “room sound” “ambient sound”…whatever you want to call it (unless of course it’s a Sunday afternoon in Pleasant Valley and the Weekend Squire is out to mow his lawn) Even so…I still take a sample of the ambient sound and apply the noise reduction. I use Audacity with noise reduction set at 6dB, sensitivity at 6.0 and frequency smoothing at 3. It takes enough “out” to make a difference without affecting the voice. What I should do is move my recording area into the closet of the room where my studio is set up. THAT would eliminate any room reflection or bounce and there would be no need to do any noise reduction.

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