How to Evaluate Voice Over Demos: 5 Red Flags in Studio Audio

You’ve found a voice actor whose demo sounds promising. The tone is right, the delivery feels natural, and something about it just clicks. But before you hit “book,” there’s one more thing you need to do.

Listen closer.

Not to the performance, to the audio itself. Because here’s the truth: the audio quality on a voice actor’s demo is exactly the audio quality you can expect for your project . And if there are problems hiding in that demo, they’re going to become your problems in post-production.

Here are five red flags to listen for and why they matter more than you might think.

1. Room Echo and “Boxy” Reverb

Close your eyes and listen to the space around the words, not just the words themselves. Does the voice sound like it’s standing in an open room, bouncing off bare walls, glass, or a hardwood floor? That’s reverb and it’s one of the fastest ways to spot an untreated space.

A properly treated booth doesn’t sound “dead” exactly, but it sounds close. The voice feels like it’s right there, with almost no sense of the room around it. If you can hear the size and shape of the space the person is sitting in – a flutter, a slight metallic ring on hard consonants, a boominess on lower tones, you’re listening to sound reflecting off surfaces that should have been absorbed with acoustic foam, blankets, or a proper vocal booth.

This one matters more than people expect, because reverb is genuinely difficult to remove in post-production. Once it’s baked into a recording, an engineer can EQ around it, but they can’t fully undo it. If it’s audible on the demo, assume it’ll be there or worse on the delivered files.

2. A Noise Floor You Can Hear

Pause the track during a silence between phrases. What do you hear? Ideally: nothing, or something so close to nothing you have to strain for it.

In the audiobook and commercial world, there’s an actual technical benchmark for this: platforms like ACX require a noise floor no higher than -60dB RMS, alongside average loudness sitting between -18dB and -23dB RMS and peaks capped at -3dB. Professional studios routinely deliver noise floors well below that, often in the -63dB to -70dB range. That’s the difference between “clean” and “broadcast-clean.”

What you’re listening for as a buyer is a faint hiss, a low hum, a computer fan, an HVAC rumble, or a fridge kicking on in another room. Any of these tells you the talent is recording in an untreated space with an inconsistent noise floor and inconsistent noise is far harder to fix than loud noise, because noise reduction software has to guess at what to remove without damaging the voice itself.

3. Plosives, Sibilance, and Inconsistent Mic Technique

Listen specifically to words starting with P, B, and T. Do you hear a soft “pop” of air hitting the microphone? That’s a plosive, and it means either the talent isn’t using a pop filter correctly or they’re positioned too close to (or off-axis from) the mic.

Now listen to S and SH sounds. Do they hiss or sizzle unpleasantly? That’s excess sibilance, usually caused by mic choice, mic angle, or proximity.

A single plosive on an otherwise excellent demo isn’t necessarily a dealbreaker, everyone has an off moment. But if you hear it repeatedly, or if the voice’s tone changes noticeably as the talent moves closer to or further from the mic within the same recording, that’s a technique and monitoring problem. It tells you the artist either doesn’t have consistent mic discipline or isn’t listening critically to their own takes before submitting them, both of which will show up again on your project.

4. Background Noise and Unedited Artifacts

Mouse clicks. A chair creak. A dog barking two rooms away. A breath that wasn’t cleaned up. These are the small, easily-fixed things that should never make it into a demo or a final delivery, because they signal one thing clearly: the file wasn’t properly edited before it was sent to you.

This matters for a subtle reason beyond the noise itself. A voice artist’s demo reel is their storefront, it’s the one piece of audio they’ve had unlimited time to polish. If there are stray artifacts in the demo, ask yourself what a same-day turnaround on your actual project is going to sound like under time pressure.

5. A Dull, Flat, or Over-Processed Tone

This last one is subtler and takes more trained ears, but it’s worth learning to recognise. Some inexpensive setups run raw, unprocessed audio, resulting in vocals that sound thin, boxy, or muffled with no presence or “air” at the top end. Others swing the opposite direction: heavily compressed, over-EQ’d audio that sounds artificially loud and lacks any natural dynamics, every syllable slammed to the same volume, with pumping or breathing artifacts around louder words.

Neither extreme is what you want. A well-recorded, well-mastered voice track should sound present, warm, and dynamic like a real person talking to you at a comfortable distance, not a voice squeezed through a phone speaker or blasted through a wall of compression.

Why This Actually Matters for Your Budget

Here’s the part that connects all five red flags together: every one of them is expensive to fix after the fact, and some can’t be fixed at all. Room tone and reverb are essentially permanent once recorded. Heavy noise reduction to fix a bad noise floor introduces its own artifacts, a warbly, underwater quality that trained ears pick up on instantly. A rushed re-record because the first delivery wasn’t broadcast-ready costs you the fee twice, plus the time you didn’t have.

Evaluating a demo for these five things takes less than two minutes per file, but it’s the difference between hiring a voice and hiring a voice and a studio, which is really what you’re paying for.

Once you know what technical flaws to avoid, check out our step-by-step guide on how to find a professional voice-over artist to match your project’s tone and style.

Listen Before You Commit

The good news is you don’t have to become an audio engineer to catch most of this, you just have to know what to listen for, and now you do.

A polished demo is a good starting point, but it doesn’t always tell you the full story about where or how the talent records. A professionally produced demo can sound excellent even when the talent’s actual recording environment isn’t at the same standard.

At The Voice Finder, we only accept talent with professionally produced demos, and we also carry out quality checks on the studios and recording spaces they use. This helps ensure that the recording quality you hear isn’t just the result of a carefully polished demo, but reflects a recording setup capable of delivering consistently professional audio.

Because here’s the truth: a great-sounding demo alone doesn’t guarantee great-sounding project files. And if there are problems hiding in the actual recording environment, they’re going to become your problems in post-production.