A twig breaks 50 yards away, a sign of possible danger. Our ancient ancestors relied on their ability to detect the location and distance of sounds, to identify its source, so they could run the opposite direction. Our auditory system, our sense of hearing evolved as a survival mechanism. Only by hearing the direct sound first can we identify its source. We use this ability when we evaluate high performance loudspeakers for their ability to deliver a pinpoint stable stereo image.
Focused Directionality vs Wider Dispersion
One essential quality of electrostatic speaker technology is its directionality. It’s a myth that this feature is somehow a curse, perpetuated by manufacturers of electro-dynamic speakers because of their use of dispersion as a feature. They made audio enthusiasts believe that dispersion was more important than focus, sacrificing directionality so more high frequencies could be dispersed into the room.
This increases the amount of early-reflected sound reaching our ears before the direct sounds, destabilizing the image and creating interference that effects the frequency response too. The critical direct sound from a conventional speaker loses 50% of its output after traveling about 3 feet, never reaching the sweet spot the way an electrostat can.
By focusing +5 dB more direct spectral energy at the listening position, electrostats reveal an un-rivaled level of resolution and clarity, with a precise stereo image that conventional speakers cannot achieve. For the owner of electrostats, its audio nirvana, invoking a feeling of bliss.
In the world of high fidelity sound, the sweet spot is defined as the listening position equidistant to each of the two front channels as they are from each other, so the arrival time of the sound is equal at your ears. If so, a stereo image appears in space in front of you that conveys a sense of utter realism; voices and instruments can be localized with specificity in the space between the speakers as if on a stage. The only person who hears it perfectly is the person in the sweet spot, that’s how it got its name. Why? Arrival time. The psycho-acoustic phenomena reveals itself only when the sound arrives at the same time from both channels. This is the “aha moment”, when you realize you cant do much to change that, that’s how stereophony works.
The term “precedence effect” means the speaker you are closest to is perceived as being louder, it’s a law of nature and evolved for our survival. Even if off-center by just one inch, one channel will be louder. Our auditory systems are governed by this rule, the stereo image loses its precision and stability when the arrival times are off by just milliseconds.