Play Sound on Keypress

class Example extends Phaser.Scene
{
    preload ()
    {
        this.load.setBaseURL('https://cdn.phaserfiles.com/v410');
        this.load.image('touhou', 'assets/pics/touhou1.png');

        this.load.setPath('assets/audio/tech');

        this.load.audio('bass', [ 'bass.ogg', 'bass.mp3' ]);
        this.load.audio('drums', [ 'drums.ogg', 'drums.mp3' ]);
        this.load.audio('percussion', [ 'percussion.ogg', 'percussion.mp3' ]);
        this.load.audio('synth1', [ 'synth1.ogg', 'synth1.mp3' ]);
        this.load.audio('synth2', [ 'synth2.ogg', 'synth2.mp3' ]);
        this.load.audio('top1', [ 'top1.ogg', 'top1.mp3' ]);
        this.load.audio('top2', [ 'top2.ogg', 'top2.mp3' ]);
    }

    create ()
    {
        this.add.image(790, 600, 'touhou').setOrigin(1);

        const bass = this.sound.add('bass');
        const drums = this.sound.add('drums');
        const percussion = this.sound.add('percussion');
        const synth1 = this.sound.add('synth1');
        const synth2 = this.sound.add('synth2');
        const top1 = this.sound.add('top1');
        const top2 = this.sound.add('top2');

        const keys = [
            'Press A for Bass',
            'Press B for Drums',
            'Press C for Percussion',
            'Press D for Synth1',
            'Press E for Synth2',
            'Press F for Top1',
            'Press G for Top2',
            '',
            'SPACE to stop all sounds'
        ];

        const text = this.add.text(10, 10, keys, { font: '32px Courier', fill: '#00ff00' });

        if (this.sound.locked)
        {
            text.setText('Click to start');

            this.sound.once('unlocked', () =>
            {
                text.setText(keys);
            });
        }

        this.input.keyboard.on('keydown-SPACE', function ()
        {
            this.sound.stopAll();
        }, this);

        this.input.keyboard.on('keydown-A', () =>
        {
            bass.play();
        });

        this.input.keyboard.on('keydown-B', () =>
        {
            drums.play();
        });

        this.input.keyboard.on('keydown-C', () =>
        {
            percussion.play();
        });

        this.input.keyboard.on('keydown-D', () =>
        {
            synth1.play();
        });

        this.input.keyboard.on('keydown-E', () =>
        {
            synth2.play();
        });

        this.input.keyboard.on('keydown-F', () =>
        {
            top1.play();
        });

        this.input.keyboard.on('keydown-G', () =>
        {
            top2.play();
        });
    }
}

const config = {
    scale: { mode: Phaser.Scale.FIT },
    type: Phaser.AUTO,
    parent: 'game-container',
    width: 800,
    height: 600,
    backgroundColor: '#2d2d2d',
    scene: Example
};

const game = new Phaser.Game(config);