Sounding Off! Page 2
You could fairly point out that the two situations are not equivalent, that even with sophisticated equalization, unlimited watts, and overdamped woofers with monstrous magnets, the interior of a car or van will always tend to go off at its preferred frequency like a giant Helmhotz resonator, and that's just what you hear, particularly from outside. That in a typical stadium, the reverberation time will be so long in the bass that unless the music is played at a funereal tempo, the low-frequency sound you hear is actually the history of the last 10 seconds of the music---"HOOWHOOM." (There's good reason why so much church and cathedral music is slow-paced.) No wonder Jeff Beck decided to do without a bass player for a stadium-based tour. And "Sound Engineer from Hell" would be an unfair and inappropriate epithet to hurl at the obviously conscientious concert technicians.
Even so, however, the level of Bozzio's bass drum was so high, and the PA system's woofers so underdamped---I wish I could have taken all the magazine's readers to the show in order to say something along the lines of "You see? A bass alignment with a Q of 5 or more leads to a complete obscuring of pitch."---that the sound of Mr. Beck's often lyrical, always gutsy Fender Stratocaster emerged from a sea of overloud low-frequency mud.
Why, however---and I'm afraid I'm sounding like my parents in the '60s here---does the music have to be played quite so loud? I'm not saying I'm against loud music. There's something physical you get from rock music played live that will never issue from a domestic system and that you never get from live classical music. (The last concert we had been to before the Beck/Vaughan event was an excellent amateur production of the Fauré Requiem: music for mind, heart, and especially the soul, but never the chest cavity.) But again, why so loud? I'd rather listen without earplugs and get a full measure of loud but clean highs than have to sacrifice what little quality there is in live sound in order to defend my hearing.
The day after the concert I discussed live sound levels with Stereophile's Captain Manyhands, Robert Harley. Bob told me an interesting fact: that at an average 93dB level, the kind of volume at which I do all my serious auditioning, it is safe to listen for four hours. But that with every 3dB increase in level, that time halves; ie, at 96dB, you can only safely listen for two hours, and at an average 102dB, which is very loud in a domestic room, 30 minutes is the safe exposure limit. At an average 114dB, which I would think typical both of the average concert sound rather nearer the PA towers than we were sitting (footnote 2) and of the woofer level in the vans at the sound-off, the maximum exposure time without potential hearing loss is just under two minutes!
So is an entire generation of Americans subjecting itself to future hearing loss? Or am I just being overanxious, particularly as the most extreme sound levels are in the bass, where the human ear is very insensitive?
I'll leave you with some quotes that caught my fancy as I was putting the finishing touches on this month's issue. According to a report in a late-November Audio Week, only 42% of CD-player owners rated them as "enjoyable," even though the 12/2/89 issue of Billboard tells us that US LP sales dropped from $2.5 billion in 1978 to an estimated $272 million in 1989. In the same issue, it was reported that 50% of the 100 top-selling albums were recorded digitally. "Digital is much more accurate," said the producer of Tracy Chapman's Crossroads album. "There's so much more dynamic range..." Now there's a man who's been to too many live rock concerts. Or does he just have a mondo in-car system?
Footnote 2: The only contemporary study of typical sound levels at live concerts that I'm aware of is by Dolby Labs' Louis D. Fielder: "Dynamic-Range Requirement for Subjectively Noise-Free Reproduction of Music" (with E. M. Benjamin), Journal of the Audio Engineering Society, July/August 1982; also summarized in "Human Auditory Capabilities and Their Consequences in Digital-Audio Converter Design," AES 7th International Conference, Toronto, May 1989, Paper 4A. To quote Fielder, "...reproduction of music at natural sound levels requires very high peak sound levels of up to 129dB spl," particularly regarding drum sets, which "are capable of producing over 40 acoustic watts." (A typical hi-fi system with a 100-electrical-watts amplifier will put out maybe 0.1 watts or less of acoustic power due to the very limited efficiency of the typical box loudspeaker.) With a crest factor of 12dB, this comes very close to an average level of 114dB, though with the very high levels of distortion featured by both in-car and PA-system sound, to assume such a high crest factor is, of course, optimistic.