We spend a lot of time listening; in fact, it’s a process that continues during most of our waking hours — unless you happen to be a college student dozing off during a lecture on 17th Century Planar Existentialism, in which case, all bets are off. However, according to research, we also even spend a fair amount of time listening while sleeping. So, unless you put in some hours in a sensory deprivation tank or possibly sleeping in anechoic chambers, listening is a 24/7 thing.
If we consider variations in inner ear anatomy, the physics of the ear canal and the shape of the outer ear cartilage among the general population, the degree of aural diversity among humans seems near infinite. And that’s before we even start tossing in other factors such as the brain itself and how it perceives (or — in the case of teenagers — refuses to perceive) sound emanating from the outside world.
The bottom line is that in terms of hearing, everyone is different — very different, as verified some 85 years ago by the research of two Bell Labs engineers by the names of Harvey C. Fletcher and Wilden A. Munson. Their research asked a large number of subjects to compare the relative volume of two tones to a standard 1 kHz tone at a set level. Averaging the results collected from the group, Fletcher and Munson defined of human hearing awareness at various frequencies.
In a landmark paper published in the October, 1933 edition of the Journal of the Acoustical Society of America, Fletcher and Munson showed that hearing is frequency selective; more specifically, hearing is most sensitive to pure tones in the 3,000 to 4,000 Hz range and less so above and below that. Essentially, to perceive that a 100 Hz signal is of equal loudness to a 3,000 Hz tone requires an actual SPL of the 100 Hz tone that’s much higher than that of the 3 kHz tone, particularly at low volumes.
Hence, the famed Fletcher-Munson curves, which proved that while each of us hears differently, there is still much in common with the way we all hear, with regards to heightened midrange sensitivity and reduced awareness to low frequencies. Unfortunately, the Fletcher-Munson curves don’t explain why the guy down the block needs quad 18-inch subwoofers installed in the trunk of his Impala. Perhaps he’s not within the calculated mean average of the subjects sampled in the Fletcher-Munson research. Or perhaps now is the time that someone should fund a re-enactment of the original Fletcher-Munson tests, but this time with a more moderne audience. (Or on second thought, maybe not…)
Yet however you hear, you must adhere to the reality that the human hearing process is a remarkable tool. Why does one sound seem “tinny” to one listener and “bright” to another? Others can listen to a strummed chord on a 12-string guitar and comment: “I think the octave string above the D is slightly sharp.” And when we mix a live show, we deal with an entire venue full of people who all essentially hear differently. In this sense, studio mixing is easier, where you only have to please yourself. And in this case, once the product leaves, the “audience” (including our friend down the block with the Impala) can play your mix on any kind of system and SPL level they want, and — like Burger King — get it their way.
But it’s no picnic for the FOH mixer who is often surrounded (literally) with patrons who each have an idea of how it should sound. Case in point: I recently attended a performance of Haydn’s The Creation — The Soli Deo Gloria, with an 80-voice choir and 20-piece orchestra in a large church. Since it was classical, of course, there was no sound reinforcement, which I’m sure someone felt would “destroy” the performance. And during one of the two intermissions, I heard a couple in front of me talking about how wonderful the church acoustics were. Well, it was plenty loud enough (even without a P.A.), but vocal intelligibility was pretty much zero unless you were in the first two rows. Here a few discreetly placed mics and a couple of properly delayed small speakers adding about 3 or 4 dB of gain to the rear seats could have made a huge difference. But no dice on that one.
This month, we have a couple interesting articles dealing with various facets of hearing. Phil Graham tackles the weighty topic of reverberation and understanding the impact and importance of RT60 measurements, while Baker Lee examines the concept of saturation and humans’ curious love affair with even harmonic distortion. Definitely some good stuff there.
Some Sad News
In the past few weeks, all of us at FRONT of HOUSE were saddened to hear about the passing of audio pioneer (and founder of See Factor) Bob See, and ML Procise, audio engineer extraordinaire and long-time executive with Showco and Clair Brothers. Our thoughts go out to the families and many, many friends of these two incredible individuals in this difficult time. May they both rest in peace.
Catch George’s editorial commentary at www.fohonline.com/tv.
