Deep noise when accelerating at 2k-3k revs when cold

[Adam]

Noticed a strange noise coming from my 02 1.6 Focus, especially when the car is cold. When accelerating in 1st and 2nd gears between 2k-3k revs, there is a change in engine sound and it sounds very deep and much louder than it does throughout the rest of the rev range.

It's hard to explain, kind of louder, deeper and echoey. Doesn't sound right to me at all.

Any thoughts?

 

[Adam]

This occured to me but it sounds more like an engine noise coming from the front of the car. Its confusing as it only seems to be at low revs when the engine is cold.

 

[Adam]

I would say mine disappears within about 5-10 mins of driving. I have had the car for about 2 months now and last week was the first time I have noticed it. Has only done 23k miles and strictly speaking its due a service (was done 2k miles ago but as this car hadn't been used it was done 1 year ago).

Wish I could describe the noise better