Intermittent sound when use AVAudioEngine

Hi, i have voice chat application, and i use AVAudioEngine to play audio after decode it, i use opus codec, from library called OpusKit and it's decode the audio fine, but when i get PCM audio and schedule it to AVAudioPlayerNode i hear Intermittent sound , not really clear, and i do not know, why this issue happend, there is no error or somthing happend.

the main process that i do is,

1 - recive commpressed audio packet from stream ( Network )

2- get the data from stream and pass it to opus decoder

3- get raw pcm Float32 pcm format like this

AVAudioFormat(commonFormat: AVAudioCommonFormat.pcmFormatFloat32 , sampleRate: 48000.0, channels: 1 , interleaved: false)

4- add the decoded packers to array list

5- in loop i get elemnts one by one, then pass it to AVAudioPlayerNode , and this is part of code

let pcmData:AVAudioPCMBuffer = self.toPCMBuffer(data: decodedDataChunk as NSData)
self.player?.scheduleBuffer(pcmData)

this is the function i use to do this task:

func openOpus(){
       
         OpusKit.shared.initialize(sampleRate: self.sample_rate, numberOfChannels: self.channel, packetSize: self.packetSize, encodeBlockSize: self.encodeBlockSize)
           
         audioEngine  = AVAudioEngine()
         self.player  = AVAudioPlayerNode()
        
         var inputNode  = audioEngine!.inputNode
         var outputNode = audioEngine!.outputNode
         let main       = audioEngine!.mainMixerNode

         audioEngine!.attach(player!)
               
         //let's get the input audio format right as it is
         let format    = inputNode.inputFormat(forBus: 0)

        
         //I initialize a 48KHz format I need:
         let format48KHzMono = AVAudioFormat(commonFormat: AVAudioCommonFormat.pcmFormatFloat32 , sampleRate: 48000.0, channels: 1 , interleaved: false)
       
       
       
        audioEngine!.connect(self.player! , to: audioEngine!.mainMixerNode, format: format48KHzMono)
                               
        audioEngine!.prepare()
        try! audioEngine!.start()                                                     
        try! self.player?.play()
       
         DispatchQueue.init(label: "play audio").async {
            self.play_audio()
         }
                     
    }

and this is the loop function

func play_audio(){
        while self.room_oppened {
           
            var frame: Data?
           
            self.serialAudioQueue.sync {
               
                if self.audio_queue.isEmpty == false{
                    frame = self.audio_queue.removeFirst() // block this part of code to get audio frame from array
                }
               
            }
           
            // FIXME: calculate the jitter bufer
            if frame != nil && self.mutted == false{
                // do the audio decoding and paly it
                if let decodedDataChunk = OpusKit.shared.decodeData(frame!) {
                    //print("we decode it  ...")
                    let pcmData:AVAudioPCMBuffer = self.toPCMBuffer(data: decodedDataChunk as NSData)
                    self.player?.scheduleBuffer(pcmData)
                } else {
                    print("failed to decode ")
                }
                let ms = 1000
                usleep(useconds_t(32 * ms)) //will sleep for 2 milliseconds (.002 seconds)
            }else{
                let ms = 1000
                usleep(useconds_t(240 * ms)) //will sleep for 2 milliseconds (.002 seconds)
    
            }
        }
    }