Trying to Check Your Voiceover Quality? Balance That Audio! Tuesday Tech Tip

Level Matching is Important

Whenever we compare audio files, it’s important to understand that volume can be misleading. A simple difference in playback levels can cause us to prefer one over the other. This is important to isolate before deciding on specific equipment or audio processing in your home voiceover studio.

If we don’t control for volume differences between audio we are listening to, it’s highly possible to make the wrong decision for effect settings or even microphone choice.

The “Loudness Effect” in recordings

It’s important to understand the “Loudness Effect.”  In simple terms, humans are biologically wired to react positively to louder sounds. I’m not saying we are all drawn to stand directly in front of the speakers at concerts (there’s probably a name for that compulsion…“Marshall Amp Syndrome”?), but when we listen to any audio – music or voice – we are more likely to prefer the one which has slightly more volume. This can mislead us.

Volume differences matter

When you start comparing microphones, this can show itself clearly. I’ve hosted “Mic Nights” where voice actors set up on 6 – 8 different microphones, and have taught separate voiceover workshops in which several microphone models are compared while performing different types of copy – balancing technical options against performance choices. You may have seen this multi-mic setup in my instagram feed. This let me capture one take through three different microphones onto three separate audio tracks – eliminating the variable of performance. 

Simply listening to those raw tracks would not be a fair comparison. Each track had a slightly different recorded level. Mic sensitivity and input gain settings varied, which caused a difference in the Loudness values on the tracks. Without Level Matching, most would have preferred the mic model which had the volume a few dB higher. 

To prevent this, I went through and RMS Normalized the audio, then confirmed that the values were correct. Students received multiple audio files recorded with these different microphones, but all were set so that the Loudness was consistent.

When comparing audio files, make sure to balance the volume level between any audio tracks 

In your DAW: Tools to balance audio

To prevent volume differences from being misleading, we have to trust the numbers.

In Twisted Wave, there’s a handy “Analyze” function under the FILE menu, Izotope RX has a “Waveform Stats” tool, Adobe Audition provides an “Amplitude Statistics” tool, and Ocenaudio provides “Statistics” under the ANALYZE menu. Other recording software should have similar tools or allow 3rd Party Plug-ins which can give this information. 

RMS (which measures the overall audio energy in a file) was the value to match. There is also LUFS – “Loudness Units Full Scale” which is becoming more of the dominant loudness scale, but most voiceover deliverables are still stated in RMS.

RMS was the key indicator. Loudness is more important than minor differences in the Peak value (the highest single wave cycle in a recording). Recording applications will allow you to adjust this by using a simple Gain tool such as “Amplify” or “Normalize” allowed matching those values in different files. Once the RMS is matched, you are ready to compare.

(Note – you should be listening through Studio Monitor quality headphones. If you don’t have any, here’s a quick overview – “How do you listen? A quick roundup of studio monitor headphones”)

Changing the EQ can cause mismatched levels

Equalizing the audio (filtering with EQ) can cause the same issue – it will effectively change the loudness and mislead your ears. Boosting frequencies will certainly increase RMS.

When we compare that EQ-boosted audio against the original, things may sound “better” because they are louder. We react to the relative difference rather than how the filtered audio actually sounds. 

It’s why an EQ (or any filtering) can sound bad when we come back to it the next day – we’ve been seduced by it being slightly louder than the original.

Applying this to your VO recordings

Working with level matched audio gives a more accurate comparison. Taking a moment to match RMS gives a better basis for comparing audition takes, EQ changes, microphone placements or even the microphones themselves. 

It’s possible to compare the audioin the same file. If I’m comparing takes for an audition, that’s usually sufficient. Reviewing Level Matched takes lets me focus on the performances. 

One way to test your audio – create a “double-blind” scenario

If I really want to do a “blind” test – say comparing microphones or EQ options – I’ll move the audio clips into separate files and balance the RMS in each. Then I’ll position the playback cursor in the different files so that pressing the SPACE bar will cause each to play from the same start point.

I want to randomize the recording I start with (again to prevent bias). In Twisted Wave, I can cycle between multiple files using COMMAND ~ (tilde) on the keyboard. Looking away from the monitor and tapping various “COMMAND `~” sets – threes, fives, twos – I’ll quickly lose track of which is which (as long as I don’t cheat and look at the screen again.)

Without sneaking a look, I listen, toggle to the next file and repeat. You’ll be surprised how quickly you notice changes (or even the lack of differences). This method lets me make as unbiased a choice as I am able to do, and usually prevents volume from being a misleading variable.

Additional Loudness Resources on JustAskJimVO.studio

UPDATE – The whole issue of Loudness in our voiceover recordings is a deep subject. In 2022, I set up a commercial audition loudness survey to explore how other voice actors approach this. If you are interested in more posts about Loudness, here are some further resources on the site:

Measuring VO Volume: How Loud Is Loud?

“Competitively Loud” Audition Recordings

Commercial Audition Loudness Survey Results

How Loud Do They Want It?

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