$cordovaNativeAudio doesn't playback audio files after a while?

I’ve got an ionic app that uses cordovaNativeAudio plugin for playing audio files. The app is kinda a foreign language dictionary where the user can listen to the vocabulary to learn how they are pronounced. The audio files have a duration of only few seconds. And I’ve got around 80 mp3 files - for each vocabulary one audio file.

I’ve noticed that in the beginning it would play the audio files just fine, but after a while the audio files of vocabularies that I haven’t played yet won’t play. Meaning I can play approx. 15 audio files. After that no other audio files can be playback that I haven’t played already.

This is the code I’m using: Each slide of my app is able to play several audio files. For each slide I wrote a code similar to this:
For slide 1:

function SoundController_slide_1($ionicPlatform, $timeout, $cordovaNativeAudio) {
    var vm = this;

    $ionicPlatform.ready(function() {
        $cordovaNativeAudio.preloadSimple('slide_1_a', 'audio/slide_1_a.mp3');
        $cordovaNativeAudio.preloadSimple('slide_1_b', 'audio/slide_1_b.mp3');
    });

    vm.play = function(sound) {
        $cordovaNativeAudio.play(sound);
    };

    return vm;
}

For slide 2:

function SoundController_slide_2($ionicPlatform, $timeout, $cordovaNativeAudio) {
    var vm = this;

    $ionicPlatform.ready(function() {
        $cordovaNativeAudio.preloadSimple('slide_2_a', 'audio/slide_2_a.mp3');
        $cordovaNativeAudio.preloadSimple('slide_2_b', 'audio/slide_2_b.mp3');
        $cordovaNativeAudio.preloadSimple('slide_2_c', 'audio/slide_2_c.mp3');
        
        $cordovaNativeAudio.preloadSimple('slide_2_d', 'audio/slide_2_d.mp3');
        $cordovaNativeAudio.preloadSimple('slide_2_e', 'audio/slide_2_e.mp3');
        $cordovaNativeAudio.preloadSimple('slide_2_f', 'audio/slide_2_f.mp3');
        $cordovaNativeAudio.preloadSimple('slide_2_g', 'audio/slide_2_g.mp3');
    });

    vm.play = function(sound) {
        $cordovaNativeAudio.play(sound);
    };

    return vm;

}

…and so on for the other slides. In total I’ve got several soundcontrollers like that. Each for every vocabulary slide. I then call them like this:

.controller('SoundController_slide_1', ['$ionicPlatform', '$timeout',  '$cordovaNativeAudio', SoundController_slide_1])
.controller('SoundController_slide_2', ['$ionicPlatform', '$timeout',  '$cordovaNativeAudio', SoundController_slide_2])

In the view I would call the audio files like this:

    <button ng-if="foo()" ng-click="vm.play('slide_1_a')" class="button icon-left ion-play">Vocabulary 1</button>
    <button ng-if="foo2()" ng-click="vm.play('slide_1_b')" class="button icon-left ion-play">Vocabulary 2</button>

And it works. The audio files are playback. But after a while it seems like I can’t load more audio files. Is the reason why after a while no new audio files can be playback is because there are so many audio files loaded already? How can I fix that? What if I wanted to implement an app that playback up to 1.000 (small) audio files?