Every iGaming studio we work with tracks the same handful of metrics: session length, Day 1 and Day 7 retention, return frequency, average bet size. Audio almost never appears on that dashboard. And yet, when academic researchers have tried to isolate which features of a slot game most directly shape how long a player stays and whether they come back, audio keeps showing up as one of the most measurable, repeatable effects in the entire experience.
This article isn't a pitch for spending more on music. It's a translation: what the research has actually found, and what it means for the decisions a producer makes when planning a new title.
1. Sound measurably changes how players experience the game
The clearest evidence comes from a study published in the Journal of Gambling Studies by a team at the University of Waterloo, led by psychology professor Mike Dixon. Ninety-six gamblers played the same multi-line slot simulator twice — once with the normal sound design, once in silence. The researchers measured skin conductance and heart rate alongside the players' own subjective reports.
The findings were unambiguous. With sound on, players showed significantly higher physiological arousal — the sweaty-palms response that correlates with engagement and excitement. They also self-reported the sessions as more enjoyable. And, critically, they preferred to keep playing the version with sound.
That last point is the one that matters for studios. Preference to keep playing is not a soft, decorative outcome. It's the engine of session length, and session length is one of the strongest behavioural inputs into return-day retention.
2. The win sound is doing more work than you think
A related finding from Dixon's research is that players consistently overestimate how often they won when the sound was on. The audio cues attached to wins — the rising chime, the coin cascade, the fanfare — created a stronger memory imprint than the wins themselves did visually.
This is not a controversial finding; it has been replicated in adjacent studies. Research from the University of Alberta, led by Professor Marcia Spetch, found that players actively prefer slot machines that include casino-related auditory cues like the sound of coins dropping, and that those cues make winning experiences more memorable after the fact.
The producer's takeaway is straightforward: a generic win sound is not a neutral choice. It's an underperforming one. The win-cascade audio is one of the single highest-leverage assets in the entire game, because it's the sound the player's brain is using to decide whether the session "felt good" — which directly drives whether they open the game again tomorrow.
3. Music shapes session length, not just mood
Earlier work by Griffiths and Parke, two of the most cited researchers in gambling psychology, proposed that background music and ambient sound in slot games create a state of emotional arousal that encourages longer play sessions and increases engagement. Later empirical work on single-line slots has confirmed this: when music is well-matched to the game, sessions get measurably longer.
Important nuance here: it's not that more music or louder music extends sessions. It's that well-designed music does. Music that fatigues the player — repetitive loops, harsh frequencies, an emotional register that doesn't match the game state — has the opposite effect, and it does so quietly. Players don't quit a session saying "the music annoyed me." They quit saying "I dunno, I just wasn't feeling it."
This is one of the most expensive misunderstandings in slot production. A studio will spend heavily on art and math optimization, then commission a single base-game music track and reuse it across an entire title. Six months later, the analytics show shorter-than-expected sessions and the team blames the math model. The math model is fine. The audio is exhausting.
4. What the research means for a slot producer
If you collapse the academic literature into the decisions you actually have to make on a new title, four things matter more than anything else:
- The win-cascade audio is your highest-ROI asset. It's the sound that disproportionately shapes whether the player's memory of the session is positive. Treat it as a tier-one deliverable, not a tier-three afterthought.
- Anti-fatigue design beats peak excitement. A track that sounds incredible in a 30-second demo can quietly kill sessions if it wasn't engineered to be heard ten thousand times. The thing your audio team should be optimizing for is the thousandth spin, not the first.
- Coherence between visual reward moments and audio reward moments is non-optional. The research is consistent that audio and visual cues amplify each other when they're aligned, and undermine each other when they're not. A great win animation paired with a flat audio response leaves performance on the table.
- Silence is part of the design. The strongest moments in a slot soundtrack are usually defined by the silence that surrounds them. Continuous wall-to-wall music dilutes every reward. The base mix should breathe so that the win moments land.
“Studios that treat audio as a retention input rather than a finishing decoration consistently outperform on session length. The cost differential is small. The compounding effect over the life of a title is not.”
5. Why this isn't priced into most production budgets
The honest answer is that audio is the only major component of a slot game whose effect on retention is genuinely hard to see in a single sprint. Art quality is visible in screenshots. Math model behaviour is visible in simulation. Audio's contribution to retention shows up over weeks, in aggregate behaviour across thousands of sessions, and it's almost never A/B tested because doing so requires shipping two versions of the audio — which most studios aren't set up to do.
So audio gets budgeted on intuition rather than on data. And the intuition tends to systematically underweight it, because nobody has ever quit a slot game in a way that obviously points at the music. They just stop opening it.
The research literature is, in effect, telling studios to correct for that blind spot.
The throughline
You don't need to read twenty years of gambling-psychology papers to make better audio decisions on your next title. You need to internalize one idea: the audio is doing a load-bearing job in the player's decision to come back tomorrow, and it's doing it whether or not anyone on the team has explicitly designed for it.
The studios whose titles consistently outperform on Day 7 retention are usually not the ones with the biggest audio budgets. They're the ones whose producers understood, before the project started, that audio was a retention lever rather than a cosmetic finish. Everything downstream of that decision — briefing, asset count, mix specifications, integration — gets easier the moment the team is aligned on it.
Selected references
Dixon, M. J., et al. (2014). "The Impact of Sound in Modern Multiline Video Slot Machine Play." Journal of Gambling Studies. · Griffiths, M., & Parke, J. (2005). "The psychology of music in gambling environments: An observational research note." · Spetch, M. L., et al. (University of Alberta). Research on auditory cues and slot machine preference, 2020.