It would be very helpful to know the precise variant of MEP which you have (18.0.2.235 is the latest version) but all variants are "paid for version(s)", there is no Free version.
However, I suspect the problem is the sample rate; 16kHz is rather low and very unusual. (That sample rate means that any audio above 8kHz will not be present, the sound will tend to be perceived as rather "dull", IMO.) MEP will expect 48kHz (the ideal) or possibly 44.1kHz. I believe it can handle 32kHz also, but not 16kHz.
So, you need to convert the existing audio to 48kHz, ideally in .wav format, and then substitute the reformatted audio for the existing audio, on the MEP timeline. As to how to achieve this sample rate conversion, several users here use MovAvi Video Convertor (paid for) though I suspect the (free) Handbrake may also be able to do this.
An educated guess from the information above, I think your issue is the same as this topic ie the audio is a non standard/unsupported format, a solution is also in the linked to topic.
Now no-way am I an expert in this area but reading this posting, I suggest that your issue is very similar to the one I had, and in which John EB gave a link above on 21st March.
My Audio about the same as yours, albeit the Sample Rate being only 8.000.
Because my issue had initially started off with stretched video on final export, in order to help finally find a way forward, instead of jotting notes on scribbled pieces of paper, I created an Excel sheet to record all details both before and after conversion in order to see what does and does not work. Initially I converted my MPEG using the free program, Handbrake, and according to my notes I see that whilst the converted clip played okay in VLC, importing into MEP, there was no audio.
I then converted the original clip using the paid for, and previously recommended on this Forum, Movavi Video Converter, which improved the Audio information with the result that it played okay in both VLC and on import into MEP. This part of my problem thus solved.