C# CSCore. Can't write pcm-wav from microphone correctly

Question

I am trying to record audio stream from a microphone to file (wav format). By default, the file is recorded in stereo, the IEEE Float codec, but I need to record audio in PCM-format (16 kHz, Mono)

Where should this format be used in this program code? (variable need_wave_format)

The project uses NuGet CSCore.

Link to this sample project: https://github.com/LordKmon/CsCoreRecordProblem

Code from winform:

    public partial class Form1 : Form
        {
            private WasapiCapture m_SoundKeeper;
            private IWriteable m_Writer;
            private IWaveSource m_FinalSource;
    
            public Form1()
            {
                InitializeComponent();
            }
    
            private void btn_StartRecord_Click(object sender, EventArgs event_args)
            {
                //Find and set Device (microphone)
                MMDevice selected_device = null;
                using (var deviceEnumerator = new MMDeviceEnumerator())
                using (var deviceCollection = deviceEnumerator.EnumAudioEndpoints(DataFlow.Capture, DeviceState.Active))
                {
                    selected_device = deviceCollection[0];
                }
    
                // Format that I needed
                WaveFormat need_wave_format = new WaveFormat(16000, 16, 1, AudioEncoding.Pcm);
    
                // Start record
                m_SoundKeeper = new WasapiCapture();
                m_SoundKeeper.Device = selected_device;
                m_SoundKeeper.Initialize();
                var soundInSource = new SoundInSource(m_SoundKeeper);
    
                var singleBlockNotificationStream = new SingleBlockNotificationStream(soundInSource.ToSampleSource());
                m_FinalSource = singleBlockNotificationStream.ToWaveSource();
    
                m_Writer = new WaveWriter("output.wav", m_FinalSource.WaveFormat);
    
                byte[] buffer = new byte[m_FinalSource.WaveFormat.BytesPerSecond / 2];
                soundInSource.DataAvailable += (s, e) =>
                {
                    int read;
                    while ((read = m_FinalSource.Read(buffer, 0, buffer.Length)) > 0)
                        m_Writer.Write(buffer, 0, read);
                };
    
                l_Status.Text = "RECORD !!!";
                m_SoundKeeper.Start();
            }
    
            private void btn_Stop_Click(object sender, EventArgs e)
            {
                if (m_SoundKeeper == null)
                    return;
                
                m_SoundKeeper.Stop();
                m_SoundKeeper.Dispose();
                m_SoundKeeper = null;
                m_FinalSource.Dispose();
    
                if (m_Writer is IDisposable)
                    ((IDisposable)m_Writer).Dispose();
    
                l_Status.Text = "...";
            }
        }
    }

Where do I should to use variable "need_wave_format" in this code so that the output is a file of the Wav-PCM format?