Interesting thoughts from Guy Fletcher, Dire Straits keyboardist....
As an audio engineer/producer who has spent most of my life inhabiting a musician’s body, one of the things that’s always intrigued me – particularly during time spent in the studio – is just how much the audio industry relies on measurements that were never designed to describe what humans actually hear.
Don’t misunderstand me – I get measurement. It can be indispensable. But I don’t believe that if it looks good on an oscilloscope, it must sound good. If one is trying to diagnose a loudspeaker or understand what’s happening in a room, a microphone is naturally the tool to turn to.
But somewhere along the line, we began to believe that because a microphone measures sound accurately, it also represents the way we experience it. It really doesn’t. A microphone is an extraordinarily precise pressure sensor. Human hearing is something altogether more remarkable. Our ears are the front end of a processing system that has spent millions of years evolving to make sense of an incredibly complex acoustic world. Your brain isn’t trying to make an accurate measurement of reality. It’s trying to understand it.
Direct sound, reflections, reverberation, phase interactions and cancellations all arrive at the diaphragm and are faithfully converted into electrical signals. If two wavefronts happen to cancel one another, the microphone reports exactly that. It doesn’t know why they’re cancelling or how much they matter.
The human auditory system, however, is constantly making judgements. It separates direct sound from reflected sound. It identifies where things are coming from. It decides what is important and quietly ignores an astonishing amount of information that would otherwise overwhelm us. Anyone who’s had a conversation in a busy restaurant has experienced this. Put a microphone on the table and you’ll capture an unintelligible soup of voices, clattering cutlery and background music. Yet somehow two people can sit opposite one another and chat quite happily.
We don’t hear everything equally, because our brains have already decided that some sounds deserve our attention while others do not. That’s an extraordinary piece of signal processing, and it’s not something that any microphone can yet do with this level of skill that we (with our ears and our brains and our millions of years of evolution) take for granted.
I’ve often wondered whether some of the compromises we’ve accepted in loudspeaker design come from forgetting this distinction. Traditional stereo has always been an elegant solution. Two loudspeakers create a remarkably convincing illusion, and when it’s done properly it works perfectly well. But it remains an illusion created by two independent point sources trying to persuade the brain that a sound exists somewhere between them. Move your head a few inches and the relationship between those sources changes.
Human hearing is an adaptive processing system, not a passive pressure sensor like a microphone. While microphones faithfully record every acoustic cancellation and interaction, the human brain actively interprets, filters, and reconstructs sound.
