Casting is the quiet superpower behind every great audio drama. Before a single line is recorded, someone decides which voice carries the hero, which one needles them, and which one makes the twist land. Get it right and listeners forget they're hearing a performance. Get it wrong and even brilliant writing feels flat.
For years, that decision belonged to producers with a rolodex of voice actors and a budget to match. AI narration changes the math. You can now audition hundreds of voices in an afternoon, cast a full ensemble solo, and re-record a scene at 2 a.m. without booking a studio.
But abundance creates its own problem. With 650+ voices in front of you, "pick a voice" becomes paralyzing. This guide turns casting from a technical guessing game into a repeatable creative process — one you can run for a single sketch or a ten-episode series.
Start with the character, not the voice
The most common casting mistake is browsing voices first. You hear a nice timbre, fall in love, and then bend your character to fit it. Reverse that.
Write a short voice brief for each character before you audition anything. Three or four lines is enough: age range, temperament, social register, and the one adjective that defines how they sound. "Retired detective, gravelly, tired but sharp, speaks slowly" gives you a target. "A cool voice" does not.
Casting directors in traditional media work from exactly these breakdowns. The Casting Society describes a character breakdown as the core document that translates a script into castable roles, capturing personality and vocal qualities before anyone auditions (Casting Society). Your AI casting benefits from the same discipline.
Build a character voice bible
Keep every brief in one document — a character voice bible. For each role, note the target descriptors, the voices you shortlisted, the one you cast, and the exact settings that made it work. This single file is what keeps Episode 7 sounding like Episode 1.
The bible also protects you from drift. When you return after a two-week break, you won't re-audition from scratch or accidentally cast a warmer voice than the character had in the pilot. You'll open the file and pick up mid-scene.
Audition voices against real lines
A voice preview reading generic filler tells you almost nothing. A voice reading your character's most difficult line tells you everything.
Pull two or three lines per character that stretch the role: a moment of anger, a whispered confession, a joke that only works with the right timing. Run each shortlisted voice against those lines. The winner is rarely the one that sounds best in isolation — it's the one that survives your hardest material.
This is where a live playground pays off. You can paste a line, swap voices, and compare instantly. Try the playground to hear candidates back to back before committing anyone to the project. Voice DNA recommendations can also narrow a huge catalog down to a handful that match your brief's tone.
Watch for the contrast test
Casting one character in a vacuum is easy. Casting an ensemble is about contrast. Two voices that each sound great can blur together the moment they share a scene, and listeners lose track of who's speaking.
Audition your leads in pairs. Put the hero's line next to the rival's and ask a simple question: could a listener tell them apart with their eyes closed? Vary pitch, pace, and accent across the cast deliberately. Audio has no faces, so the voice has to do the work of identification that a camera would otherwise handle.
Turn casting into a repeatable project
Once you've cast the ensemble, you need a workspace that remembers your choices. This is where a multi-voice project workflow separates a real production from a pile of one-off clips.
In EchoLive's studio editor, a script lives on a segment-based timeline, and each segment carries its own voice, style, and pacing. You assign the detective's voice to his lines once, then every one of his segments inherits it. Change a character's read across the whole episode with batch operations instead of re-editing line by line.
That structure is what makes casting a decision rather than a chore. You're not re-selecting a voice 200 times; you're casting a role once and directing it everywhere. When a scene needs a different emotional read, you adjust that segment's style without disturbing the character's baseline voice.
Give each character consistent direction
Casting is only half the performance — direction is the other half. Use per-segment controls to shape delivery: slow the pace for a tense confession, add emphasis on the line that turns the scene, insert a beat of silence before the reveal.
For finer control, EchoLive's visual SSML editor lets you build breaks, emphasis, and prosody without hand-writing markup, though you can drop into raw SSML when you want it. Small, consistent choices — a character who always pauses before lying, a narrator who never rushes — build the vocal identity that makes a cast feel like real people.
Let AI write the two-hander when you need it
Not every audio drama starts as a finished script. Sometimes you have source material — an article, an interview, a research paper — and you want to dramatize it as a dialogue between two distinct voices.
EchoLive's Conversational Audio turns an article, URL, YouTube video, or PDF into a natural two-host conversation, then produces it as multi-voice audio. The AI drafts the script; you cast a voice per host. It's a fast way to prototype a two-character dynamic before you commit to a full ensemble, or to spin up a companion "discussion" episode alongside your scripted drama.
Audio drama itself is having a genuine renaissance. Edison Research's long-running work on audio consumption documents steady growth in on-demand and spoken-word listening, and podcasting has pulled scripted fiction back into the mainstream (Edison Research). The appetite is there. The barrier used to be production cost — and that's exactly the barrier AI casting removes.
Ship it, then listen like an audience
Casting choices that look right on paper sometimes fall apart in a full listen. Export a rough cut and play it end to end, the way a listener would — in the car, on a walk, doing dishes. Voices that felt distinct in isolation may crowd each other; a lead you loved may drag across a long scene.
When the cut sounds right, publish it. Any finished piece can become a public listen link that plays with no account required, so you can share a scene with collaborators or drop the full episode to your audience. For heavier post-production, export MP3, WAV, segment bundles, or timeline JSON into your editor of choice.
If you're weighing tools before you commit a whole series, it's worth comparing how multi-voice workflows differ across platforms — see EchoLive vs Descript for one example of how project structure changes the casting experience.
Voice casting with AI isn't about finding one magic voice — it's about running a clear process: brief the character, audition against hard lines, cast for contrast, and lock those choices into a project that remembers them. Do that, and consistency stops being a fight and becomes the default. When you're ready to cast your ensemble and hear them read your lines, open EchoLive and start building your first multi-voice scene.
Originally published on EchoLive.
