Episode Overview

Podcast: Twenty Thousand Hertz
Host: Dallas Taylor
Episode: Defying Gravity: The Audio Wizardry of Wicked's Live Vocals
Date: November 19, 2025

This episode dives deep into the revolutionary approach to recording live vocals on the set of the movie adaptation of Wicked. Host Dallas Taylor and guest Simon Hayes (Production Sound Mixer) explore the technical and artistic challenges of capturing live singing amidst the chaos of filmmaking, how their team defied industry norms, and the magical results their innovations unlocked.

Key Discussion Points & Insights

The Challenge of Movie Musical Vocals

• Industry Norms: Most movie musicals pre-record actors’ singing in studios, then have them lip sync on set due to noise and logistical issues. This disconnect can often be heard in changes in vocal tone and performance energy.

  • “On Old School Musicals, they weren’t singing live, they were miming to a playback track.” — Simon Hayes [03:24]

• Wicked’s Bold Choice: Wicked’s filmmakers insisted on live, on-set vocal performances for authenticity, demanding unprecedented audio technique.

  • “What I wanted to do in Wicked was… we don’t want to hear this transition between singing and dialogue because there isn’t a transition because it’s all live on the set.” — Simon Hayes [04:40]

Capturing Pristine Audio in a Chaotic Environment

• The Role of the Production Sound Mixer: Simon Hayes describes his central responsibility: to ensure the “cleanest vocals possible” survive to the final cut.

  • “If I have a bad day at work… the actors will have to come in, they’ll have to re-record their vocals.” — Simon Hayes [06:10]

• AVOIDING ADR: Automated Dialogue Replacement (ADR) is common but rarely matches live performance authenticity. The episode details its pitfalls, including tonal disconnect and lack of natural reverberation.

  • “We never get the actors back in together to ADR their piece… there will almost be a disconnect for the actor.” — Simon Hayes [07:02]
  • “Someone that doesn’t understand filmmaking… may just be living, looking at the actors, facial expressions, listening to the tonality of their voice and thinking, I don’t trust this.” — Simon Hayes [07:38]

Technical Innovations: Mics and Mixing

• Consistent Close Miking: To avoid tonal shifts, dialogue was recorded as intimately as the singing, often using lavalier microphones, even when this required visible placement and later digital removal (VFX).

  • “I wanted that close up dialogue so there was no transition into the singing voice.” — Simon Hayes [09:05]
  • “If it’s a bit of velvet, a bit of chiffon, a bit of silk, it’s either going to be rustling or it’s going to sound muffled… so we just put the microphone straight on the outside and it was removed in post.” — Simon Hayes [11:06, 11:17]

• Boom Mics as Backup: Multiple boom mics were still used for flexibility, sometimes “jostling for position” just out of frame and occasionally painted out in post-production.

  • “Even if Ari and Cynthia are singing absolutely nose to nose… we always had two boom mics.” — Simon Hayes [12:24]

• Presenting the Director with Choices: Hayes recorded multiple isolated tracks (from both lavs and booms), providing editors with editorial flexibility in post.

  • “I’m presenting him with choices… how he wants the final film to sound.” — Simon Hayes [12:59]

Preserving Performance Energy in Duets

• Instead of asking actors to “mime” during the other’s close-ups (for clean solo tracks), both leads always sang live, capturing the genuine emotional dynamic between them.

  • “Every single time, it was like their vocals meshed. Something very, very magical happens when those two start dueting together.” — Simon Hayes [14:32]

• The audio team prioritized capturing that immediacy, even if it meant more work in post.

  • “You can sing over each other as much as you want to. We will work it out as best we can in post production.” — Simon Hayes [14:32]

The Wicked Ensemble & Thumper Tracks

• Chorus Vocals: Large ensemble numbers blended live recordings (for realness and raw energy) with perfectly sung studio overdubs (using singers from the Broadway show).

  • “There was this very, very raw and real part of the way that they were performing that sounded like they were angry villagers.” — Simon Hayes [21:33]

• Foley Realism: A “thumper track” (a deep, sub-bass rhythm routed only to dancers’ in-ear monitors) enabled them to record synchronous movement and stomping—without any musical leakage.

  • “We would take the sub bass… the sweet spot was 38 hertz... get them all doing their stamping… in tempo to the track.” — Simon Hayes [22:52, 23:16]

In-Ear Monitors and VFX Camouflage

• Discreet Monitoring: Cast wore color-matched in-ear monitors to hear the accompaniment. For close shots, IEMs were painted out with VFX.
  • “We basically got that exact color match for her [Cynthia’s] IEMs.” — Simon Hayes [25:10]

Flexible Tempo: Bridging Live Emotion with Backing Tracks

• Allowing Expressive Timing: To facilitate emotional delivery, soloists sometimes sang along to live keyboard accompaniment (in IEMs), with pre-recorded tracks crossfaded in at certain musical cues.
  • “We allowed the actors to go off tempo with a keyboard, but still knowing that at a certain point the drums and the bass was going to come in.” — Simon Hayes [26:37]
  • “Her first verse and a half was completely freeform… you can just feel her emotions.” — Simon Hayes [27:47, referring to Cynthia Erivo’s ‘I’m Not That Girl’]

The Ultimate Test: “Defying Gravity” Goes Live

• Flying & Singing: The episode’s climax details the most daunting scene: Cynthia Erivo singing “Defying Gravity” while performing aerial stunts, amid wind and wire rigs.

  • “What are you going to do about defying gravity? Cynthia’s flying through the air. Surely she’s going to lip sync to that.” — Simon Hayes [16:02, revisited 29:33]

• Silent Wind Innovation: Wind effects were created with ducted, offstage fans and piped air, minimizing mic noise that would traditionally force ADR.

  • “All I could hear was a kind of broadband shhh, which… can be removed from the vocal pretty easily these days.” — Simon Hayes [30:48]

• Set-Wide Quiet: Even hydraulics for stunt wires and camera tracks were silenced for clean vocals.

  • “We just all pulled out every single stop to make what would normally be an actual sequence in a superhero movie… quiet.” — Simon Hayes [31:47]

• Cynthia’s Confidence: When asked if she wanted to sing live while flying, Cynthia Erivo simply replied, “Of course I’m singing live.” [32:40]

• Result: “It was an Olympic level of gymnastics that she was doing and singing completely perfectly… only Cynthia could pull that off. It was something just unprecedented.” — Simon Hayes [33:08]

Notable Quotes & Memorable Moments

• “I think that we made the right decision because when Ari and Cynthia started singing together… it was like their vocals meshed. Something very, very magical happens.” — Simon Hayes [14:32]

• “What I realized when I started in the film business is that sound is performance, and I love performance.” — Simon Hayes [33:27]

• “I thrive on being able to say to my directors and my actors, I got it. It sounds great. That’s the best feeling in the world for me.” — Simon Hayes [34:32]

Important Timestamps

• 03:24: Simon Hayes explains traditional playback/lip syncing in movie musicals.
• 04:40: Hayes emphasizes goal of “no transition” between speech and singing in Wicked.
• 06:10: The consequences of poor on-set sound and reliance on ADR.
• 09:05: Decision to record dialogue as intimately as vocals for seamless transitions.
• 11:17: Discussing the use of visible lavs and their digital removal for best audio quality.
• 12:24: Use of multiple boom mics for lead actors, even during close duets.
• 14:32: Impact of preserving live duet energy between leads.
• 21:33: Blending raw live ensemble with Broadway-quality overdubs.
• 22:52: Introduction and explanation of “thumper track” for choreography.
• 25:10: Custom color-matched in-ear monitors for on-set musicianship and VFX.
• 26:37: Technique for live tempo flexibility using keyboard in IEMs.
• 29:33: The “Defying Gravity” challenge: singing while airborne.
• 30:48: Silent wind technique explained.
• 32:40: Cynthia Erivo’s insistence on singing live during flight sequences.
• 33:08: Simon effuses about the magic of Cynthia’s performance.

Episode Tone and Flow

• The tone is technical but deeply passionate, celebrating both audio craft and musical performance. Simon Hayes clearly reveres the artistry and emotional truth of the actors, while Dallas Taylor’s narration is engaging, curious, and explanatory—perfect for both newcomers to sound production and musical aficionados.

For Listeners New to the Episode

This episode reveals the hidden artistry and technical wizardry behind Wicked’s celebrated “live singing” soundtrack. With behind-the-scenes anecdotes and fascinating breakdowns of both tech and teamwork, it challenges assumptions about what’s possible in Hollywood musicals—and leaves you listening for the real sound, every time.