调用示意

        // 静音和取消静音
        AudioSys.instance.muteMusic();
        AudioSys.instance.cancelMuteMusic();
        AudioSys.instance.muteSound();
        AudioSys.instance.cancelMuteSound();

        // 播放音乐
        AudioSys.instance.playMusic(this._testMusicClip);
        // 播放音效
        AudioSys.instance.playMusic(this._testSoundClip);

        // 退出游戏时销毁
        AudioSys.instance.myDestroy();

AudioSys.ts

import { AudioClip, AudioSource, Component, director, game, Game, Node } from "cc";

export class AudioSys extends Component
{
    private static _instance: AudioSys;
    public static get instance(): AudioSys
    { 
        if (!this._instance)
        { 
            let rootNode: Node = new Node('AudioSys');
            director.addPersistRootNode(rootNode);
            this._instance = rootNode.addComponent(AudioSys);
            this._instance.init();
        }

        return this._instance;
    }

    private _musicAs: AudioSource;
    private _soundAs: AudioSource;

    private static readonly MinMusicVolume:number = 0;
    private static readonly MaxMusicVolume:number = 0.5;
    private static readonly MinSoundVolume:number = 0;
    private static readonly MaxSoundVolume: number = 1;
    private static readonly MusicFadeDuration: number = 1;
    private static readonly MusicFadeInterval: number = 0.05;

    public get isSoundMute():boolean
    {
       return this._soundAs.volume == AudioSys.MinSoundVolume;
    }
    public get isMusicMute():boolean
    {
       return this._musicAs.volume == AudioSys.MinMusicVolume;
    }

    onDestroy()
    {
        this.myDestroy();
    }

    private init(): void
    { 
        this._musicAs = this.createAs(AudioSys.MaxMusicVolume, true);
        this._soundAs = this.createAs(AudioSys.MaxSoundVolume, false);
    }

    private createAs(volume:number, isLoop:boolean): AudioSource
    { 
        let curAs: AudioSource = this.node.addComponent(AudioSource);
        curAs.clip = null;
        curAs.loop = isLoop;
        curAs.playOnAwake = false;
        curAs.volume = volume;
        return curAs;
    }

    public myDestroy():void
    { 
        let node:Node = AudioSys.instance.node;
        node.destroy();
        AudioSys._instance = null;
    }

    // 音乐：静音
    public muteMusic(): void
    { 
        this._musicAs.volume = AudioSys.MinMusicVolume;
    }
    // 音效：静音
    public muteSound(): void
    { 
        this._soundAs.volume = AudioSys.MinSoundVolume;
    }
    // 音乐：取消静音ß
    public cancelMuteMusic(): void
    { 
        this._musicAs.volume = AudioSys.MaxMusicVolume;
    }
    // 音效：取消静音
    public cancelMuteSound(): void
    { 
        this._soundAs.volume = AudioSys.MaxSoundVolume;
    }
    // 播放指定音乐（传入clip， 默认循环，淡入淡出）
    public playMusic(clip: AudioClip): void
    {
        this.unschedule(this.musicFadeIn);
        this.unschedule(this.musicFadeOut);

        if (this.isMusicMute)
        {
            this._musicAs.stop();
            this._musicAs.clip = clip;
            this._musicAs.play();
            return;
        }

        if (this._musicAs.clip)
        { 
            // 淡出淡入
            this._musicAs.volume = AudioSys.MaxMusicVolume;
            this.schedule(this.musicFadeOut, AudioSys.MusicFadeInterval, AudioSys.MusicFadeDuration / AudioSys.MusicFadeInterval, 0);
            setTimeout(() =>
            {
                this._musicAs.stop();
                this._musicAs.volume = AudioSys.MinMusicVolume;
                this._musicAs.clip = clip;
                this._musicAs.play();
                this.schedule(this.musicFadeIn, AudioSys.MusicFadeInterval, AudioSys.MusicFadeDuration / AudioSys.MusicFadeInterval, 0);

            }, AudioSys.MusicFadeDuration*1000);
        }
        else
        { 
            // 直接淡入
            this._musicAs.volume = AudioSys.MinMusicVolume;
            this._musicAs.clip = clip;
            this._musicAs.play();
            this.schedule(this.musicFadeIn, AudioSys.MusicFadeInterval, AudioSys.MusicFadeDuration / AudioSys.MusicFadeInterval, 0);
        }
     
    }

    private musicFadeOut():void
    { 
        let volume = this._musicAs.volume - (AudioSys.MaxMusicVolume - AudioSys.MinMusicVolume) / (AudioSys.MusicFadeDuration / AudioSys.MusicFadeInterval);
        volume = volume < 0 ? 0 : volume;
        this._musicAs.volume = volume;0
    }
    private musicFadeIn():void
    { 
        let volume = this._musicAs.volume + (AudioSys.MaxMusicVolume - AudioSys.MinMusicVolume) / (AudioSys.MusicFadeDuration / AudioSys.MusicFadeInterval);
        volume = volume > AudioSys.MaxMusicVolume ? AudioSys.MaxMusicVolume : volume;
        this._musicAs.volume = volume;
    }

    // 播放音效（传入clip）
    public playSound(clip: AudioClip): void
    { 
        this._soundAs.playOneShot(clip, 1);
    }
}

额外知识：CocosCreator中，关注Toggle的状态变化

// 关注
this._musicToggle.node.on('toggle', this.onClickToggle, this);
// 移除关注
this._musicToggle.node.off('toggle', this.onClickToggle, this);

// 直接设置状态
this._soundToggle.isChecked = true;

private onClickToggle(t:Toggle):void
{
    if (t.isChecked)
    {
         // doSth
    }
    else
    {
         // doSth
    }
}