Small Speakers, Big Impact: Maximizing Mobile Game Audio for Small Speakers.

A Guide for Sound Designers & Composers to Optimise their Audio for Mobile Speakers

As a freelance sound designer, I’ve worked on a number of mobile games and it hasn’t always been possible to review the audio on a native build before release. Because of this, and due to the nature of the playback system of the mobile platform - small phone speakers, it can represent a unique challenge in making sure the audio translates well to mobile devices.

According to this article by Touch Arcade, in 2013 only 3% of players worldwide were playing mobile games while using headphones. While not a reliable statistic now, the vast majority of people playing mobile games are still experiencing their game’s audio through phone speakers.

So it's vital we spend the time making sure our mobile game’s audio sounds great on mobile speakers. Especially if we are unable to test our audio on a mobile device before launch. But how can we do this?

The following tips have worked well for me and will help your mobile game’s sound translate better on mobile speakers than if you didn’t take into account the limitations of mobile speakers.

Does Sound Matter in Mobile Games?

It’s vitally important.

Sound can impart brand recognition with your game just as much as a logo, characters or artwork can.

Additionally, 73% of the people playing mobile games are playing with the sound on.

Making sure your mobile game’s audio sounds great will make your game more recognisable, fun and people will spend more time playing it.

As you can see, it’s important to get your mobile game’s audio to a high standard.

The Frequency Limitations of Small Speaker Systems. 

Smaller speakers inherently have less of a frequency response than large speakers.

Here is an excellent blog post on the Audiokinetic website that goes into depth reporting the loudness and frequency response of popular smartphones. I’ll summarise some of the key takeaways here.

Mobile speakers tend to drop off at around 800Hz. This will vary from handset to handset, but as a general rule of thumb it’s a safe starting point to work with. 

4-5kHz can be particularly pronounced on mobile handsets, so be extra careful with elements in this range. A build up in this frequency band will get fatiguing to listen to quickly - which could potentially result in people spending less time playing your game.

There is also high frequency falloff, but the amount varies depending on the handset. Some of the earliest fall off is at 10kHz.

Put together, this frequency profile is unique and limiting and we must keep it in mind if we are to effectively create audio for mobile games.

Preparation

Before even beginning to work on the sound effects or music for a mobile game, it would be worth reviewing the limitations of the playback system and planning your work accordingly.  

For composers, it might be helpful to choose instrumentation that works well within the frequency profile of a mobile’s speaker system.  

For sound designers, it could be useful to be thinking about working with more mono assets than you might normally.

Being mindful of the mobile platform from the start will make your audio translate better.

Simulating a Mobile Playback System inside your DAW

In order to replicate the frequency response of mobile playback systems, I like to set up an EQ on my master with a high pass filter at around 800Hz, 400Hz and 200Hz (switching between them while reviwing work) to replicate the loss of those frequencies you’ll experience on mobile speakers.

I will also boost between 4 and 5kHz by a few Db to simulate the sensitivity of that frequency band on mobile.

It might look something like this:

An EQ setup to replicate the frequency response of mobile speakers

Then, while I’m working on the sound effects for a mobile game, I’ll ocasionaly turn this EQ on to check my audio. I’ll be listening for things like: how much infomation gets lost - do some of my sounds need extra layers to sit within a certain frequency range to help them cut through? Also, how is my work affected by the loss of the low end - which will be substantial and will need addressing.

To account for the loss of low end when you try this approach, try subtle Distortion or Saturation to add upper harmonics to your bass and low end elements to help them become more audible in our limited frequency range.

If your audio still sounds good with this EQ on, you can be confident it will translate well on mobile.

Don’t forget to bypass it when rendering your work though.

Monitor at Lower Volume Levels 

Low level listening will expose the sounds and elements of the mix that are either too loud or too quiet.    

If your audio still has impact, definition and clarity at low levels, you can be confident that it will sound great on mobile speakers.

Check your Mix in Mono

This is good advice no matter what our intended playback system might be, but it’s doubly important for a mobile game’s audio. 

Many mobile phone speakers are either mono or the speakers are so close together that they can appear to be mono from our perception. 

If your work sounds good in mono, it will translate nicely to mobile speakers. 

Takeaway

By now I’ve shown:

1. Audio for mobile games presents a unique set of challenges due to the limitations of small speakers and not always having access to a playable build on mobile to test on.

2. We can simulate the limitations of small speakers within our DAW to ensure our audio translates as well as possible.

3. By taking special care and being thoughtful in our approach, the mobile games we’re working on will sound great as a result.

I hope you’ve found this article useful.

Get in touch if you need professional sound design for your mobile game and want to take it’s audio to the next level. I’d love to hear about your project!

The Author

This article was written by Oliver Smith. A long-time remote working freelance sound designer dedicated to making gameplay enhancing sound for games.