Hi LazyJ,
This is a term that is tossed around with little clarification. It really depends on what you are referencing it to. . .real-life sound levels? If real life, measured at what distance from the source? The front row in Carnegie Hall, or the first Tier halfway back? The levels the audio engineer mixed at? (Usually excessive, and much louder than life, in my experience.)
If memory serves, the THX level for movie theater playback is an average of 85 dB SPL measured in a mid-audience location. Subjectively, that's termed "quite loud" (and it is). It's also routinely exceeded in lots of cinemas. I fled a press showing of one of the Star Wars movies at the Zeigfeld theater in New York because the peak levels were away above 100 dB SPL (and I was at least halfway back in the movie theater).
Amplified rock in concerts reaches levels of 110 dB and louder (there are bylaws to control this, seldom enforced) but levels like that, if it's cleanly amplfied, are far more tolerable outside or in a club than in your living room at home.
The loudest peaks I've ever measured in concert halls with a 150-voice choir and full orchestra are about 106 dB SPL in the first ten rows of the orchestra section. From a first tier balcony seat at the side of Carnegie Hall, peaks of 96 to 100 dB SPL are not uncommon with large choral/orchestral works.
At home, I often listen to music peaking between 85 and 90 dB SPL at my listening position. It's realistic and enjoyable at those levels, even thrilling at times, and occasionally, at the risk of offending neighbors, I'll up the ante with peaks between 95 and 100 dB.
Listening-level tastes vary quite a bit from one person to another. Colleagues of mine routinely listen at levels at least 3 to 6 dB louder than my preferred levels.
Regards,
