QAudioRecorder example produces only a buzzing sound

I have a usb frame grabber with a microphone attachedto it.
I have tried to capture that device by VLC player to check whether it is working or not. It works fine, I can hear the sound.

http://doc.qt.io/qt-5/qtmultimedia-m...r-example.html
Following are the settings in the GUI of QAudioRecorder which I selected.

I selected the output file with the extension .wav.

Attachment 12081

And the settings of VLC player are here:

Attachment 12082

As we see that VLC codec info says **"araw"** and I have selected **"wav"** as the container format.

Is that making a difference?

What do I need to look in to find why am I getting only a buzzing sound through QAudioRecorder but not through VLC player?