"Hotter" CD's in the pop jenre all have to do with marketing. When artists hear their song on the radio, and it is quiter than the next guy, they get upset. Most pop cd's have been mastered with TREMENDOUS amounts of compression and peak limiting. The reason being to have the disc play "as loud as possible". Fletcher/Munsen were the first psycoacousticians to create an average frequency responce vs. spl graph of human hearing. At louder absolute levels, our ear/brain mechanism tends to smooth out and become more "flat". At lower listening levels, we become less sensitive to bass frequencies and high frequencies. That's why you see "loudness" buttons on some older gear. It boosts the bass and high frequencies to make the level appear louder without turning up the volume knob. What I'm getting at is the same piece of music, played louder, will tend to sound "better" than the quiet version.
Now, if you look at most pop CD's released today on a digital meter (DAT deck, CDR etc) you'll notice that, if the mastering engineer did what he was told, the meters will be pegged at 0dBfs and jiggle up and down by no more than 3 db. At this level of dynamic range, a 16 bit recording has the mathematical dynamic resolution of a 4 bit PCM recording system. What the hell is the point? Classical orchestral discs (if mastered properly with minimal if no limiting or compression) for example sound quieter because, even though the musical PEAKS reach 0dBfs (1111111111111111), the avarage level (mezzo forte) lies at about -10dBfs. The quiet parts (Pianissimo) can be at the -30 to -50dBfs point. This is a dynamic range of 50dB! That's what truly tests a 16 bit system! But even in the classical field, we engineers are feeling the pressure to make as loud a CD as possible. That's why it's not unheard of to use a peak limiter to bring the average level of the CD up a couple to 3dB. Even a little bit of limiting is audible though, and those of us with a conscience avoid it like the plague.
Now, if you look at most pop CD's released today on a digital meter (DAT deck, CDR etc) you'll notice that, if the mastering engineer did what he was told, the meters will be pegged at 0dBfs and jiggle up and down by no more than 3 db. At this level of dynamic range, a 16 bit recording has the mathematical dynamic resolution of a 4 bit PCM recording system. What the hell is the point? Classical orchestral discs (if mastered properly with minimal if no limiting or compression) for example sound quieter because, even though the musical PEAKS reach 0dBfs (1111111111111111), the avarage level (mezzo forte) lies at about -10dBfs. The quiet parts (Pianissimo) can be at the -30 to -50dBfs point. This is a dynamic range of 50dB! That's what truly tests a 16 bit system! But even in the classical field, we engineers are feeling the pressure to make as loud a CD as possible. That's why it's not unheard of to use a peak limiter to bring the average level of the CD up a couple to 3dB. Even a little bit of limiting is audible though, and those of us with a conscience avoid it like the plague.