audioEngine = AVAudioEngine()

let unitEffect = AVAudioUnitReverb()
unitEffect.wetDryMix = 50

audioEngine.attach(unitEffect)

audioEngine.connect(audioEngine.inputNode, to: unitEffect, format: nil)
audioEngine.connect(unitEffect, to: audioEngine.outputNode, format: nil)

audioEngine.prepare()

do {
    try audioEngine.start()
} catch {
    print(error)
}