ionic play notification sound
import { NativeRingtones } from '@ionic-native/native-ringtones/ngx';
constructor(private ringtones: NativeRingtones) { }
...
this.ringtones.getRingtone().then((ringtones) => { console.log(ringtones); });
this.ringtones.playRingtone('assets/ringtones/sound_1.caf');
this.ringtones.stopRingtone('assets/ringtones/sound_1.caf');