タッチしている時間が短すぎると音がならない

Question

Swift3です
以下のコードで、ボタンを押した時間が短すぎると(チョン押し)音がなりません。
Apple製のGaragebandのように、押している間だけ音がなり、チョン押しでも少しだけ音がなる仕様を実現したいです。
ご教授願います

import UIKit
import AVFoundation

class ViewController: UIViewController {

let pianoKeys = ["C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B"]

var audioPlayers:[AVAudioPlayer] = []


override func viewDidLoad() {
    super.viewDidLoad()
    
    for key in pianoKeys {
        let pianoSoundURL = URL(fileURLWithPath: Bundle.main.path(forResource: key, ofType: "m4a")!)
        
        do {
            
            let audioPlayer = try AVAudioPlayer(contentsOf: pianoSoundURL)
            audioPlayer.prepareToPlay()
            audioPlayers.append(audioPlayer)
        } catch {
            
        }
    }

func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
       }

}

@IBAction func Pushed(_ sender: Any) {
    let keynum = (sender as AnyObject).tag
    audioPlayers[keynum!].currentTime = 1
    audioPlayers[keynum!].play()
    //touchdown
}

@IBAction func Released(_ sender: Any) {
    let keynum = (sender as AnyObject).tag
    Thread.sleep(forTimeInterval: 0.03)
    audioPlayers[keynum!].pause()
    //touch up inside
}



@IBAction func Releasedoutside(_ sender: Any) {
    let keynum = (sender as AnyObject).tag
      Thread.sleep(forTimeInterval: 0.03)
    audioPlayers[keynum!].pause()
    //touch up outside
}