Slot Game Audio


As a music composer, I get to work on a wide gamut of very interesting projects, from meditation music incorporating binaural beats to notification sounds and ringtones for a mobile device.

And yet, I was still surprised to find myself landing a job with a slot machine developer as the resident composer for their games. Till today, people I meet are always intrigued by my work. It hadn’t occurred to them that there could be an actual human being behind the sounds blasting out of the machines across the casino floor.

That said, the job has been plenty fun! I get to compose in a wide range of styles, from epic Asian orchestral scores (Chinese game themes) to EDM and big band jazz. Just so our game products remain competitive, I also get to work with the best instrument sample libraries on the market and the latest audio softwares.

The makeup of game audio

The first slot protoype invented in the late 1800's by a car mechanic Charles Fey was built from a cash register-sized box with actual playing cards for its pictures and a bell that rang when you hit a winning combination.

Today, the machines are much more sophisticated with slot games that resemble AAA video games in spectacular visual displays and sounds. This means the slot games composer/sound designer would do well to learn from the audio work heard in successful video games.

As we produce many games each year, we have to constantly come up with innovative themes or popular legendary stories that will in turn inform the audio concept for the games. In each game, I am tasked to create a completely new batch of audio assets that reflect the game's theme:

  • background music echoing the mood of the theme

  • snappy ditties to accentuate flashing animations

  • music jingles to celebrate wins

  • attention-grabbing sound effects that draw players

Thanks to the ever-changing nature of the game themes, I need to be flexible as a composer and well-informed on the music theory and arrangement distinct to various music genres. Having to work on Egyptian, Asian, jungle safari, big band jazz, and EDM themes, I would be much remiss to not know what a double harmonic major is or a production technique like sidechaining a sound to a “ghost”. The "reel spin" and "reel landing" sound might differ accordingly too - laser zap for disco theme or bell clink for Chinese theme.

Importantly, the "bonus spin" icon needs to attract the player's attention and will pop out of the screen with a highly animated sequence accompanied by a striking sound like the a tiger's roar or the crash of a China gong. Similarly, any important event in the game has to be highlighted with an animation or sound/ditty.

Due to hardware limitations, I have to ensure the background music loops seamlessly. This affects the creative process, but it does push me to be more innovative in working within such limitations as a composer.

Sky is the limit, and it all boils down to composer's approach to problem-solving.

Psychology behind slot games

There is one constant to note in slot game audio - the sounds have to exude Unikitty-like POSITIVITY.

Quite obviously, players like rewards and will stop playing a game if the rewards dry up. Revolving the sound design around a reinforcement schedule, how often players are rewarded for certain actions, helps create positive reinforcement and boost player satisfaction, hence bolstering the attraction of the game.

For each win, I create jubilant jingles that vary in duration and musical elaboration according to the size of the wins. Mini wins trigger a 1-2 second jingle played by a synthesizer. Huge wins trigger a 30-45 second jingle recorded in a full orchestral arrangement. Most importantly, the win jingles are created not just for the players but to also attract passers-by to the winnings and the game.

Even the right musical key can help generate positivity.

Legacy slot games used to centre their sounds in the key of C, a particularly pleasant chord which a study in Finland even claims instilled a feeling of happiness and nostalgia in listeners.

Today, as the slot industry gets increasingly competitive in new technology and game designs, the field has opened up and games pretty much feature all the key centres of Western music. Shifts in music tonal keys help games stand out even more with sonic signatures, and punctuate significant events during game play. Celebratory sounds are tied to wins or even partial losses, acting as positive reinforcement. Conversely, no unpleasant sound corresponds to a loss. Remember, only positivity folks!

One important thing to remember though, there can also be too much of a good thing. Rewarding every inconsequential event with an exultant jingle can end up misleading and numbing players to the sounds, thereby inversely reduce player motivation.

People respond differently to different types of rewards, so it is important to do extensive game testing to find the right balance of reinforcement schedule.

Attention grabbing audio tricks

Assuming the perfect timetable of win jingles has been decided on, I still need to tread carefully between creating an unforgettable earworm or a sound so annoying it chases the player away - sacrilegious in the world of slot games, no big surprise there.

Since the early 1900s, slot machine manufactures have been crafting high-pitched winning sounds that are audible above the loud ambient noise of the casino environment. This helps draw attention to the machines and player, thereby also enhancing the player's self-esteem.

Winning combinations trigger a loud ringing bell; a legacy carried over from the first slot machine ever built. Credits are counted up with a satisfactory rolling sound. Exciting near-misses, where the last reel stops just below or above a high-paying symbol in a close reel match, are highlighted by thrilling ascending tones. Andbonus rounds - the highlight of slot games - are accompanied by action-packed soundtracks and explosive sounds.

Each and every sound coming out of the machine serves only one mandate alone - to capture and sustain the attention of players.

However to compete with the barrage of audio artillery from other games, sounds are pushed to the extent that they get sometimes discordant, repetitive, and jarring. A sound designer needs to come up withsmart aural tricks to hack the player's listening without annoying them. I always leave volume boost as the very last resort, and instead try working on EQ, sidechain compression, and instrumental re-arrangement to create clarity.

The future of slots

The casino industry has always kept abreast of the latest in technological advancements like cloud computing, 4K Ultra HD displays, surround sound speakers and hydraulic motion-chairs that move players in sync with the video on-screen. The race for constant improvements are part of an overarching goal to create a “sensory-immersion gaming” experience for players whose expectations are constantly on the rise.

This just means that we as composers also need to keep a tap on the trends in not just the music industry but also in our clients' industries. Takes an effort to do all that, but it is a small price to pay in the highly competitive world of production music.

4D AR slot game anyone?