FLETCHER MUNSON LOUDNESS CONTOUR CURVES
The loudness contour curves illustrated at the left show the required amount of bass boost when lowering the volume of your sound system if you are to get a similar impact from the sound at lower volumes. The numbers going up are the volume while the numbers going left to right are frequency. The lower frequencies start at the left of the graph. The ear is most sensitive to sounds located near 4000 Hz. It can be seen that according to these curves a substantial bass boost is required even at the higher volumes. ETL/Reflex™ technology allows you to enjoy a unique property of TBI™ Bass Extension Modules that maintains a balanced sound at very low volumes without an electronic boost. The sounds simply remains completely intact at whisper levels with all of the low frequency nuances present in full detail. This amazing feature has defied all measurements as related to the original F-M curves because no electronic bass boost function is employed. The intelligibility benefits when a time locked fundamental-harmonic relationship exists between the Bass Extension Module™ and the mains.
Our theory shows us that the method of low frequency generation employed by the scientists of the time (which is the same as the present) was flawed and qualified reproduced sounds only for this effect. TBI™ Bass Extension Modules produce the low frequencies in a manner never before attempted with the driver loading entirely in an ideal environment not the ambient. This isolated acoustic processing generates low frequency waves as a product of the ETL™ environment with no external influences therefore maintaining a natural sonic presence in the listening room as the natural instrument would. Synthesized acoustic mass maintains proper power response at all levels for enhanced low volume intelligibility.
If we think about the natural sounds of our environment including natural musical instruments that are played at various levels during the course of a performance it is a ordinary condition that some of these sounds will be louder than others and the mental interpretation is that of the natural sound. We don't have a desire to raise the volume of the natural event because it wasn't loud we simply hear it as it should be heard. You really can't lower or raise the volume of a naturally occurring sound but with TBI™ Bass Extension Modules you will be as close as possible to doing that.