How Do Professionals Listen?
It's fairly well-known that recording engineers, producers, and recording artists listen at fairly high playback levels when recording and mixing. But just how loud is the mix they listen to? And what effect do these sound-pressure levels have on their hearing? I've been around recording studios and have been exposed to what I considered high SPLs, but nothing prepared me for an experience at the studio of Bruce Swedien, engineer of many of Michael Jackson's records, including Thriller and Bad. Swedien is also a producer and songwriter with 13 Grammy Awards to his credit.
I was standing a few feet behind the console when he said he'd play part of the new Michael Jackson record he was working on. He threaded the paper leader tape on the analog tape machine (paper leader is placed at the front and backâ"head" and "tail"âof each mixed song), sat back down at the console, and pressed "Play" on the remote control. I watched the paper leader going past the tape heads, and the instant that the leader ended and the tape oxide hit the playback head, I felt a concussive shock wave hit my body. My stomach felt like wiggling Jello, my knees weakened, and I instantly felt nauseated. I thought I would either pass out or vomit. All this happened in the first two seconds.
After 30 seconds of this, he stopped the tape, and it was like a crushing weight had been lifted from me. I expressed my shock at the insane playback level, asking why it needed to be so loud and whether he was concerned about long-term hearing damage. He explained that such sound-pressure levels tell him things about the recording he wouldn't otherwise hear, and that he felt the levels were safe because, "We limit those kinds of levels to fifteen minutes a day."
The Occupational Safety and Health Administration (OSHA) sets maximum exposure limits for sound in the workplace. An increase in the allowable level reduces the maximum exposure time. The maximum SPL for an eight-hour day is 90dB. At 115dB, the highest SPL allowed by law for any duration, the maximum exposure time is just fifteen minutes. At 100dB SPL, workers can be exposed for up to two hours. These levels and durations are thought to be just below the threshold of causing permanent hearing damage.