Fletcher and Munson were pioneering researchers who established many basic concepts of High Fidelity in the '30s. They accurately measured and published a set of plot curves that showed the human's ear's sensitivity to loudness verses frequency. The curves show the ear most sensitive to sounds in the 3 kHz to 4 kHz area and sounds above and below 3-4 kHz must be louder in order to sound balanced at lower volume levels. These are the curves that most "Loudness" circuits are based on. |
