On 08/05/2011, at 8:28 PM, Niran Bala wrote: > How should I interpret this value? > > When I mute the Mic on my laptop, this value is -120
My GUESS (only) would be that this is the line level, which is logical, since it couldn't possibly be actual sound pressure level, since the signal is amplified through some unknown amplifier and speaker system before becoming sound. Decibels are only a relative measurement, there's not really any such thing as a "decibel" as a physical quantity. You can express a relative measurement in terms of decibels, or you can qualify the level against some reference standard in decibels, for example 1dBm is 1mW of power, and the ear-splitting 120dB SPL is referenced to a pressure of 20 micropascals rms. You need to find in the documentation or ask what 0dB is considered to be in this measurement system. --Graham _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
