# Sound Check in iTunes - what is it REALLY doing?



## ndurantz (Aug 10, 2008)

I was listening to my Oppo the other day through my desktop set-up (Orb Mod1s w/ Mirage sub through NuForce Icon) and noticed the sound was significantly more "visceral" than when I listen to the Apple Lossless version played back off my Mac Mini using the NuForce as the DAC.

After thinking it may be my speakers, my NuForce, etc it occurred to me that maybe I am looking for the dynamics and that maybe having the sound check feature applied in iTunes is the culprit. However, I am not sure I fully understand what sound check is doing. Is it actually compressing the dynamic range or something else? :scratch:

Any thoughts on the subject would be greatly appreciated!!


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## eugovector (Sep 4, 2006)

To be properly implemented, it would simply "normalize" the gain level, in other words, maintain the relative difference between the loudest and softest parts of a song, while keeping them at the same average level relative to other songs.

The latest reports were that Soundcheck DID NOT "compress" the music, that is, reduce the difference between the loudest and softest parts of a track while raising overall levels. This could change anytime apple decides it wants to implement compression to lessen the deficiencies in the earbuds they package and most people use.


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## ndurantz (Aug 10, 2008)

eugovector said:


> To be properly implemented, it would simply "normalize" the gain level, in other words, maintain the relative difference between the loudest and softest parts of a song, while keeping them at the same average level relative to other songs.
> 
> The latest reports were that Soundcheck DID NOT "compress" the music, that is, reduce the difference between the loudest and softest parts of a track while raising overall levels. This could change anytime apple decides it wants to implement compression to lessen the deficiencies in the earbuds they package and most people use.


That is great info. Where'd you find it?

Follow-up question - the soundcheck is simply done at the point of playback correct? For example, I rip a CD, import it into iTunes and have soundcheck applied for playback in iTunes. If I then sync that track to my iPod, it simply syncs the track, allowing the soundcheck to be applied from the iPod during playback. Am I understanding correctly?


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## eugovector (Sep 4, 2006)

http://www.head-fi.org/forum/thread/367375/itunes-sound-check-any-affect-on-sound-quality

Sound Check should not change the music file, only the associated normalization info. In other words, it should damage your file, if you don't like it, turn Sound Check off.


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## ndurantz (Aug 10, 2008)

eugovector said:


> http://www.head-fi.org/forum/thread/367375/itunes-sound-check-any-affect-on-sound-quality
> 
> Sound Check should not change the music file, only the associated normalization info. In other words, it should damage your file, if you don't like it, turn Sound Check off.


Thanks for the link. Turn it off - simple solution, right? Think that is what I will be doing when I am doing some serious listening. Otherwise, if background music, think I will leave it on. Thanks for all the info! :T


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## eugovector (Sep 4, 2006)

You're welcome.


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