As T-cut says the tensioner can give a similar noise.
How long does the noise last for and does switching on aircon, operating the steering make it any louder or last longer ?
After a cold start the alternator puts a high load out and this can cause that twitter on a belt with a bit of glazing till the load falls off,
To see if it is the belt or tensioner bearing, before a cold start give the belt and pulleys a misting with water, if it stops the twitter it is more than likely from the belt/pulleys.
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