Umami is a word first coined in 1908 by Japanese chemist Kikunae Ikeda to describe the taste of glutamates and nucleotides. It is one of the five basic tastes (together with sweetness, sourness, bitterness, and saltiness). In simpler terms, we can describe Umami as a savory, "brothy" or "meaty" tasting element with a long-lasting, mouthwatering, and coating sensation over the tongue. Umami is what gives food a robust, full flavor. It's the difference between empty and incomplete tasting—thin—vs. rich, hearty, and fulfilling.
When I try and categorize how a product sounds, its level of Umami always comes to mind. No, of course I don't "taste" sound, but I very much relate the same emotions of richness, heartiness, fullness, and satisfaction to what I hear.
We're all familiar with a product that starts out sounding good but soon reveals itself as thin and threadbare. We know this because it has no staying power. We don't want to sit and listen for hours on end to music. It is empty and the opposite of rich, hearty, and fulfilling in its presentation of music.
I can forgive many products of their sins but not this one.
Music, to be satisfying, enriching, soul-nourishing, needs Umami.