I have a 5 year old Honda Jazz, which has done 37k miles.

Within the last 2-3 weeks I've noticed a slightly odd noise when starting the car up. It also is audible when at traffic lights, it seems to only be obvious when starting the car up having not used it for a few days. The noise can only be described as the chunky kind of engine noise a diesel car makes. However, to make things far easier, I have recorded the sound and uploaded it here:

www.zshare.net/download/82532690fb0b5307/

At about 4-5 seconds it is most obvious. Bear in mind that there is background 'air' type noise but if you listen carefully, it's quite easy to make out the noise I'm talking about.

Is it a fan or auxiliary belt? I basically know next to nothing about cars, but can't help but worry when my car makes an odd noise. I immediately envisage extremely expensive repairs.