Code and Stuff

Using sound in React Native

by Don on August 31, 2020 underprogrammingreactjavascript

As indicated in previous entries, I’ve been working on a Round Timer application in React Native, both as a project to try out React Native and as something I could actually use while working out. This has been a little slow going, as I do it in my free time and between other projects, but the basic version of the timer is progressing nicely and reaching a finishing point.

That brings us to today’s topic - using audio in the application. As of 2020, it seems that audio is still not super well supported (or, rather, not at all supported) by React Native itself. So we have to use some community solutions. At the moment, I’m using the react-native-sound library from zmxv. This library doesn’t seem particularly well maintained anymore, but it seems to have a lot of use. I’ll probably try out the react-native-audio-toolkit to see if it works out a little better.

So, first, you have to install the library.

npm install react-native-sound --save

The official instructions have a step on linking, but this is apparently no longer necessary. Nevertheless, I did run this step:

react-native link react-native-sound

Now with the library installed, we can import it into our component:

import Sound from "react-native-sound";

We then set the sound category.


And finally, we create our sound.

var bell_end = new Sound("bell_end.mp3", Sound.MAIN_BUNDLE, (error) => {
    if(error) {
        console.log("Failed to load the sound", error);

Now, according to the official documentation, when working with Android, the sound files need to be located at android/app/src/res/raw/, and they must be lower cased with underscores. In my case, this folder didn’t exist, so I had to create it, and then I dropped my files in there. Now, to actually play the sound: => {
    if(success) {
        console.log("Sound played");
    } else {
        console.log("Failed to play sound");

And now, our sound should work! Should. In practice, it didn’t. Instead, it kept giving me the error:

null is not an object (evaluating 'RNSound.IsAndroid')

I searched around for a little while and there were a lot of different recommendations on how to fix this, and none of them worked for me. Some of the solutions were probably a result of an older version of React Native, where things were done differently; for instance, it was recommended that the package be added in the, it was recommended to make changes to the gradle files, and so on. What finally fixed the issue for me was going into my Android emulator, completely uninstalling the existing version of the app, then returning to my terminal and running android again.

react-native run-android

Once this built and deployed to the emulator, I stopped getting the error. But, my sounds still wouldn’t play. Initially, it couldn’t find the resource - I honestly have no idea how I fixed this aside from doing another deploy. But once it could find the resource, it would nevertheless indicate that it had failed to play the sound. I put in a call to bell_end.getDuration() just to see if it was even getting the proper information about the file, but it was just giving me a value of -1.

Looking around for solutions to this a bit more, I saw various people saying they had trouble getting the sound to play on the Android emulator, but that it worked fine on their actual device. I decided to see if that was the case for me, so I set my device up for USB debugging, connected it to my computer and deployed the app. Sure enough, the sound worked just fine! So, it seems like there’s something the emulator doesn’t like about this process. I suppose I’ll be using my actual device more going forward!

© 2023 Don Walizer Jr