Fletcher originated threshold measurement, loudness relations, and masking models

Evidence

Fletcher was the first to accurately measure auditory threshold, the first to measure the relationship between loudness and intensity and loudness and frequency. Further, he developed the model of masking in application still today. His experiments led to the modern-day audiogram and contributed to our knowledge of loudness (discussed in Chapter 4). — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 89