Behind the scenes: How Slots Sound Design is Heading for The Next Level

Sound design within online slots is becoming ever-more sophisticated and immersive, as the battle reigns to keep players engaged. But how is modern-day game music developed, how is it meeting regulatory challenges and what will come next in this fascinating sphere of development?

We speak to Lightning Box CPO David Little, Michael Salih, Lead Game Producer at Wizard Games, Stellita Loukas of Stellita Lukas Creative – Sound Design for Kalamba Games, Relax Gaming Sound Designers Joseph Cherry and Per Klintberg, and Wazdan’s CCO Andrzej Hyla to find out.

Q: How important is sound in creating an entertaining, atmospheric online experience?

David Little: Whilst some disagree and some players even play with it off, the sound is of equal importance as the graphics and animation in any game for me. If the maths stimulates your imagination and the graphics provide a visual feast, then the soundtrack and the aural triggers within a slot bring a whole other one of our senses – hearing – into play. It is a central ingredient in the mix; without it, you don’t have the full package.

Andrzej Hyla: Game’s music and sound play a pivotal role in elevating any slot experience to the realm of the extraordinary. A perfect example of this is our game Sizzling Moon™, with the galactic adventure paired with a fittingly intense soundtrack that reflects the magnificent theme on display.

Upon entering the game, players are met with epic music and sound effects that project the grand nature of the slot, with a deep, punchy, trumpet-inspired soundtrack that aims to ramp up the intensity of the experience. The epic background music intensifies and becomes

more dramatic in the Bonus game, increasing the excitement and engaging players more deeply. It gives the game a sense of epic scale that would be difficult to achieve otherwise.

Stellita Loukas: Very. Our auditory system is one of the core ways in which we make sense of the world around us. Sound is therefore a key part of creating a convincing environment that will draw players in and keep them engaged for long periods of time. If audio is important in console games, it is ten times more important in slot games. 

While often not given the attention it deserves, audio can make or break a game since it lends credibility (or lack thereof) to the game environment. Try watching a thriller without the sound on – about 80% of the experience is gone!

Michael Salih: Very important. Players see the visuals first and hear the sound second. You want to keep your players engaged and entertained at all times and sound design plays a leading role. Slot music is usually short one-minute tracks that are looped and you need to make sure it is balanced nicely with the in-game sound effects and is still enjoyable to listen to after the 100^th time of experiencing it.

Joseph Cherry: Sound makes a huge difference. It can get at our emotions in a way that pure visuals simply can’t. It can be a delicate balancing act though – we’ve all experienced that one repeating sound effect in a game that just drives us crazy, and it can ruin the experience. But when it’s done right, it can elevate the experience to a whole new level.

I have found that adding subtle personal touches helps a lot with this. Whenever possible, I try to use real instruments, bespoke recordings, and even sing myself if the game demands it. For instance, if players load up The Great Pigsby Megapays they’ll be treated to my very best Sinatra impression!

Q: Have player expectations of sound design for slots changed in recent years and how will this evolve moving forward?

Stellita Loukas: Definitely. Since more and more developers are realizing the importance of audio, players have come to expect increasingly higher quality sound – not only in terms of the content itself but also in terms of production and implementation quality. Sound is finally catching up with slot graphics and animations that are getting closer and closer to resembling AAA console games. 

Michael Salih: There are certainly still players who still prefer the classic slot visuals and sounds. However, over the years, many providers have upped their games by producing higher quality art and animation and with that comes higher audio expectations from the player.

In the case of Wizard Games, we plan to take our audio quality one step further. Music within our upcoming games will have improved orchestrations, tailor-made unique melodies, live recordings of various instruments, brilliant vocals recorded live, and custom voiceovers from professional actors and actresses. We’ve been improving many different elements in our game production to elevate the brand, and evolving our sound design is an important part of that. Mixing and mastering are being worked on by a professional audio engineer using analog equipment, sound effects tailored using state-of-the-art audio equipment and audio libraries specifically created for our projects. Audio for animations are being better synced, the effects are custom-made, and our audio department is part of the quality assurance (QA) and creation process.

Per Klintberg: From the perspective of a creative professional, I would like to think it’s the more ambitious and innovative takes on what a casino game can be that drive development and raises expectations.

While I find it difficult to imagine that traditional reels or cascade games will ever go out of fashion, coming up with new experiences is important to attract players, as well as ensuring the industry remains an interesting and challenging field for creatives.

In Relax’s game Marching Legions, the soldiers perform haka-style moves to celebrate wins. Even a couple of years ago, the audio during these animations would have been a lot simpler but we pushed the boat out and delivered something that’s of the same standard as a movie or a console game. The player can clearly hear everything from the rustling gear to the swooshing of the swords as well as the grunting and shouting of the soldiers. I did this at home during the pandemic. Recording the vocals was fun – you have to reach a certain level of outrageousness to match the animations, and after a while, the neighbors’ dog started barking. I took that as approval.

David Little: They have changed beyond recognition and there is huge potential for even further development. When I started in the industry, we had pretty ordinary 8-bit technology at our disposal.  We then got stereo, which was a game-changer. Some-land-based games now utilize sub-woofers, with casinos even incorporating shaking chairs to add to the fully immersive effect.

In the online arena, and on mobile devices, in particular, file size presents a challenge, as audio can take up a fair chunk of the total. As we move to 6G and phones that hold a terabyte of data this will improve. But until then – and maybe even then – there will always be a balance between delivering a brilliant aural experience and not draining the life out of the player’s phone or tablet.

Andrzej Hyla: Expectations for sound quality have grown at the same rate that the online casino industry has. In a land-based setting, there is a great deal of noise from all directions so the sound from a given machine doesn’t need to be particularly innovative. An online slot game is a far more personalized experience, so players have grown to expect similar sound quality that they might get from other forms of home entertainment like console gaming or films. This has tasked us with upping our sound design abilities massively in recent years, and I’m delighted to say we have found ourselves equal to the challenge.

Q: Has the progress of technology, particularly on mobile devices, assisted in putting more sophisticated soundtracks and effects in front of players? What restrictions are still in play when creating sounds suitable for on-the-go play?

Joseph Cherry: To be honest, it’s made it a lot more challenging. You have to be much more conscious of things like game size, which means finding creative ways to make fewer sounds do more in-game. This is particularly tricky with music. We aim to create tracks that don’t get dull over time, but they also can’t be overly long. Of course, limitations can breed creativity and I really enjoy finding smart and dynamic solutions to keep games sounding fresh.

You also have to consider what the sounds will be played on. Laptop speakers, headphones, or even just straight out the phone all sound very different and so we have to test mixes on all devices to be sure it sounds great across the board. 

Andrzej Hyla: When creating mobile-first games, developers have to bear in mind that each game should be optimized to increase the loading speed. What is more, on-the-go players launch games in various places, while on public transport, for example, where loud sound effects may irritate people nearby.

As a result, when launching our games on mobile, game sounds are muted by default. However, we adjusted our mobile control panel to ensure they can be easily switched on by clicking a dedicated button.

David Little: When HTML was first used for mobile devices, you couldn’t play more than one sound at a time.  You could load one long track and the program would then choose which part of the track to play.  In short, it was very clunky.  We can now layer sound over sound for a much richer feel and line up certain visual actions along with the correct sound.  Play on the go is fine if players are willing to put their earbuds in.  But some people don’t like that and will instead play with the sound off.  In my view, they’re missing out on half the fun!

Michael Salih: It isn’t about the devices as such, but more about moving away from old technology such as MP3s and adopting smaller, better-quality formats such as OGG and M4A. That said, the true magic will always remain in the hands of the audio engineer. We remain restricted in terms of overall package sizes as we all want our games to load as quickly as possible, wherever a player happens to be across the world. It’s a balancing act between sophistication and all the required assets downloading quickly, including images and animations.

Stellita Loukas: Yes and no. Technological advances are of course driving the audio quality upwards but the need for extensive compatibility with older devices still keeps mobile slot audio from reaching its full potential. The mp3 file format, for example, which is quite old and low-quality by today’s standards, is still being used because it is compatible with a lot of older devices. 

What is more, the on-the-go play does not, unfortunately, lend itself to the same luxuries as desktop computers or even tablets that one can use in the comfort and privacy of their homes. Unless a player is equipped with high-quality noise-canceling headphones, there really is no way to compete with the noise and distractions of on-the-go play. 

Q: To what extent does regulation shape sound design – for example, where a sound effect might imply a win that is less than the stake?

Michael Salih: Regulatory requirements have been fairly easy to comply with. For example, with wins that are less than the stake, we simply show a splash text of the amount and a short ‘ding’ sound. For higher wins, we will visually count up the win along with ‘count-up’ sounds or big win presentations, so that it is easily distinguishable to the user that the sound effect is a correct representation of the amount received.

Per Klintberg: We’ve taken a straightforward approach and chose to not have any big highlights or animations playing on wins below bet. This means that the only audio cues played are those tied to the counter. Often those cues also follow the winning factor, so the player will notice a clear difference between lower and higher wins.

Andrzej Hyla: Regulation affects everything we do, from broad company strategy to elements of game design, such as sound. It is vital we conform to each jurisdiction’s demands, for example, when it comes to avoiding small wins celebrations. However, it then becomes part of the challenge to make sound stand out in other ways, be it adding to the atmosphere of the game, rather than highlighting spin results. Regulation is important and shapes everything we do.

David Little: For my money, this is less about regulation and more about doing right by the player. It’s just wrong to play an over-the-top celebratory win tune when you have in fact won less than your stake. That said, some recognition that you retained some of your money is not just appropriate but necessary. How far you push that envelope is up for debate, obviously. Most studios choose not to celebrate, rather just indicate that you did indeed get some of your bet back. The same applies to visual cues too, obviously. Throwing up coins and associated sounds when you don’t win is going to annoy players pretty quickly, so why do it?

Q: Will there ever be a time when an online game – perhaps in the metaverse – has audio as impactful and immersive as can be found on dedicated cabinets?

Andrzej Hyla: Absolutely, we are getting to a point where the headphones that people have to hand can create all the sound fidelity that the speakers in the best cabinets can replicate. Players that want to enjoy a truly immersive experience will be happy to purchase such technology. When smartphones became the norm we started creating games that take full advantage of the opportunities these devices offer and our approach has been no different with regard to sound.

David Little: The main issue studios face is they can’t ever predict what device a player will be enjoying the game on.  Different players in different countries around the world have access to different technologies, not to mention personal preferences.  If they’re listening through their Dolby headset it will be a completely different experience to someone on an iPhone 6.  The advantage a cabinet has from a design point of view is that know what you’re dealing with technology-wise each-and-every time.  We are also restricted with file size, especially now that iOS bundles are restricted to a maximum size.  For operators it becomes a trade-off: do you go with more games of lesser size, or fewer games with more size? There’s no correct answer to that conundrum.

Stellita Loukas: The extent to which the audio of an online game is impactful and immersive depends, to a large extent, on the equipment of the player. If the audio itself is high-quality, then a very good pair of headphones can go a really long way! 

Michael Salih: As a VR player myself, we are a long way off a Ready Player One experience with video games. VR is still pretty niche and has not yet been adopted by the masses. That being said, the video gaming industry is constantly pushing forward year after year, so who is to say that more iGaming companies won’t venture into the metaverse eventually, as more people start using improved VR technology.

Per Klintberg: High-end cabinets are sometimes kitted out with high-end speakers, multiple screens, tilt capacity, mechanical transducers, and so on. It can be difficult to compete with those. The cabinet’s environment is often noisy though, whereas coupling a good set of headphones with your phone can provide extremely crisp audio fidelity, providing the immersion that we aim to deliver.

Regarding moving beyond stereo audio for games on the web, I think it hinges on hardware and standards. Providing convincing 3D audio that translates reasonably between playback systems requires more than two physical channels.

For stereo, the alternative is to process the audio. We’ve seen quite a few solutions from both pro-audio and consumer manufacturers without any of them reaching wide acceptance. However, the web audio API has spatial positioning, so when a playback solution gets traction, we can start working with it. In the meantime, we have many ways of making audio elements swirl around your head and seemingly beyond the speakers.