Incorrect value in decibel measurement AVFoundation

I get on the output wrong decibel value when silent get 0.00 if I create noise goes up to 0.02 - 0.03. Something I do wrong, because I measured with another application with silence, I get about 20 db, with noise about 50 db.

struct NoiseMeterView: View {

    let audioRecorder: AVAudioRecorder
    @State var timer: Timer?
    @State var decibels: Float = 0

    init() {
        let audioFileURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0].appendingPathComponent("audio.m4a")
        let settings = [
            AVFormatIDKey: Int(kAudioFormatMPEG4AAC),
            AVSampleRateKey: 16000,
            AVNumberOfChannelsKey: 1,
            AVEncoderAudioQualityKey: AVAudioQuality.high.rawValue
        ]

        do {
            audioRecorder = try AVAudioRecorder(url: audioFileURL, settings: settings)
        } catch let error {
            fatalError("Error creating audio recorder: \(error.localizedDescription)")
        }
    }

    var body: some View {
        VStack {
            Text("Noise Level: \(String(format: "%.2f", decibels)) dB")
                .font(.title)
                .padding()
            Button(action: {
                if timer == nil {
                    startMetering()
                } else {
                    stopMetering()
                }
            }) {
                Text(timer == nil ? "Start" : "Stop")
                    .padding()
                    .background(Color.blue)
                    .foregroundColor(.white)
                    .cornerRadius(10)
            }
        }
    }

    func startMetering() {
        do {
            try AVAudioSession.sharedInstance().setCategory(.record)
            try AVAudioSession.sharedInstance().setActive(true)
        } catch let error {
            print("Error setting up audio session: \(error.localizedDescription)")
            return
        }
        audioRecorder.isMeteringEnabled = true
        audioRecorder.record()
        timer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { _ in
                audioRecorder.updateMeters()
                var decibels = audioRecorder.peakPower(forChannel: 0)
                decibels = min(max(decibels, -120), 0)
                self.decibels = pow(10, (decibels / 20))
            }
    }

    func stopMetering() {
        timer?.invalidate()
        timer = nil
        audioRecorder.stop()
    }
}