Rocky and the Art of Creature Voices: Inside Project Hail Mary’s Sound Design

In this Science Friday episode, Flora Lichtman chats with film sound designer Eric Adahl about Rocky, the alien from Project Hail Mary. They explore how Rocky’s voice was built, from a bass didgeridoo to layered gurgles drawn from humpback whales and birds, slowed to a musical range, with an ocarina for calmer moments and a raspier contralto clarinet for impatience. The discussion also delves into Rocky’s Eridian language, its internal consistency, and the idea that about 250 scripted words give Rocky a distinct voice. The show also touches on Adahl’s work on Godzilla’s roar and a Tree of Life sound moment, illustrating how sound design can drive cinematic emotion as much as visuals.

Overview

In this episode of Science Friday, host Flora Lichtman interviews sound designer Eric Adahl (credited on Project Hail Mary and other films) about the artistry and science behind creating Rocky, the alien in Project Hail Mary. The conversation centers on whether Rocky’s language is a fully developed, internally consistent system and how the sound team approached Rocky’s voice and vocalizations. Adahl shares his philosophy of sound as a core emotional driver and walks through the process of designing a creature language that feels authentic while remaining accessible to human listeners.

"the voice conveys the soul and the spirit"

"the voice brings Rocky to life, and it’s a huge part of the movie"

Rocky’s Voice and the Vocal Palette

Adahl explains how Rocky’s voice is built from a blend of real-world sounds with careful frequency selection to avoid muddiness and to maintain a bold, simple sonic identity. The bass line is anchored by a didgeridoo, establishing a grounded, earthy pulse. For the layered, gurgling textures, he incorporates humpback whale sounds and references to thrushes, a family of birds known for their beautiful songs. A slowed-down solitaire bird recording provides the melodic center that human ears can interpret as musical and expressive. This layered approach gives Rocky a voice that feels simultaneously alien and emotionally legible to the audience.

"there’s about 250 scripted words for Rocky"

"the sleuths out there who want to go do some forensic sound examinations can probably spend a year trying to parse all that out"

Consistency, Context, and Language

The discussion moves to how the eridian language is crafted with consistency. Once Rocky’s voice was established, the team worked to ensure that a word for sleep or other concepts would stay consistent across contexts, even as context shifts the emotional weight of a word. Lichtman notes the importance of consistent vocal direction and world-building through sound, which helps the audience infer Rocky’s culture and identity without explicit exposition.

"the language is actually consistent"

"there might be a different context, and so it might be performed a little bit more intensely or a little bit more calmly"

Sound Ingredients, Instrumentation, and Recording

Adahl details the palette of instruments used to realize Rocky’s vocalizations, including the ocarina for calmer moments and a contralto clarinet for more edge and rasp when Rocky is agitated. He also discusses technique such as recording at ultra-high resolutions (192 kHz) and slowing down audio without fidelity loss to extend ranges and craft a more musical register that aligns with human hearing. The playful, exploratory nature of the process is highlighted as a core strength of foley and design work.

"we used an ocarina"

"you can close your eyes and you can put a label to it, like, oh, that sounds annoyed"

Other Iconic Creature Voices: Godzilla and Tree of Life

The episode shifts to Eric Adahl’s broader experience shaping monster roars. He recounts the challenge of updating Godzilla’s roar for the 2014 film to respect cinema history while leveraging modern technology. He describes a four-month period of experimentation, the role of dry ice in vibrating metal to generate a whale-like foundation, and the elephant trumpeting that opens the inhale before Godzilla roars. Lichtman uses this as a bridge to discuss how sound design operates in tandem with visuals to drive emotional impact. The Tree of Life segment illustrates a Terence Malick project where Adahl created a sound for the universe expansion, calling it the ‘Sound of Eternal Silence’ after a direct conversation with the director about abstract sonic storytelling.

"there are happy accidents that weren’t intentional"

"don’t tell me what the sound is until we’re done, but I told him and he named it the Sound of Eternal Silence"

Closing Thoughts and How Sound Shapes Emotion

In closing, the host and guest reflect on how sound design informs perception and emotion, potentially shaping audience response as powerfully as imagery. They invite listeners to consider how sonic choices contribute to the film experience and encourage interest in the craft of sound editing and design.

"sound kind of comes in through the back door and images come in through the front door"

"the art of sound is a malleable expressive tool"