Lot of sound volume fluctuation?

[Racineur]

Hi, I'm playing with my new iMac with ML 10.8.4 and I notice a lot of sound volume fluctuation. First with Mail new email sound alert. So faint, I cannot rely on it to be warned of new emails. The sound alert is faint even if the sound is maxed in the Prefs. I DL Boom to get somme oomph and I like it but the fluctuations are more audible now. It's a bit confusing. Does someone here has the same problem and have a solution or info on this?
Thanks

 

[ricede]

Is this a new MacbookAir ?

It appears that there have been sound fluctuation problems with this latest model. If you do have one of these models - check software update because apple have released a fix for it.

Sorry missed the ref to iMac.

 

[yliu]

Check your settings. Do you have another mac to compare with?