Whining sound from gearbox maybe?

Hi,
I have just bought a Nissan Almera 1.8 from 2004 with a manual transmission.
One thing i have noticed, is that it makes a slight whining sound that will pitch up with the engine speed, and then the whining will disappear when the engine speed increasing,
or if i press the clutch pedal down.

I have recorded the noise here https://instaud.io/1RR6
It also has a weird sound on cold starts, which i also recorded https://instaud.io/1TxK
what could be the problem?

Help is much appreciated!

All the best
Patrick

Really dumb question, If the noise was there during the test drive why did you buy it.?

I would drain the trans and refill it with the exact lubricant specified by Nissan. My Honda Civic says to use Honda oil, which I do, but 10W30 can be used temporarily in an emergency. Who knows what the previous owners may have used?