     ///   - noteNumber: MIDI Note Number
     ///   - velocity:   MIDI Velocity
     ///
-    open func play(noteNumber: MIDINoteNumber, velocity: MIDIVelocity) {
+    @objc open func play(noteNumber: MIDINoteNumber, velocity: MIDIVelocity) {
 
         // MARK: Microtonal pitch lookup
         // default implementation is 12 ET

    ///   - velocity:   MIDI Velocity
    ///   - frequency:  Play this frequency
    ///
    open func play(noteNumber: MIDINoteNumber, velocity: MIDIVelocity, frequency: Double) {
        AKLog("Playing note: \(noteNumber), velocity: \(velocity), frequency: \(frequency), override in subclass")
    }


@objc open class AKPolyphonicNode: AKNode, AKPolyphonic {

    /// Global tuning table used by AKPolyphonicNode (AKNode classes adopting AKPolyphonic protocol)
    @objc open static var tuningTable = AKTuningTable()
    open var midiInstrument: AVAudioUnitMIDIInstrument?

    /// Play a sound corresponding to a MIDI note with frequency
