Since the emergence of the study of psychoacoustics in the 1930s, most lists of elements of music have related more to how we "hear" music than how we learn to play it or study it. C.E. Seashore, in his book "Psychology of Music", identified four "psychological attributes of sound". These were: "pitch, loudness, time, and timbre" (p. 3). He did not call them the "elements of music" but referred to them as "elemental components" (p. 2). Nonetheless these elemental components link precisely with four of the most common musical elements: "Pitch" and "timbre" match exactly, "loudness" links with dynamics and "time" links with the time-based elements of rhythm, duration and tempo. This usage of the phrase "the elements of music" links more closely with "Webster's New 20th Century Dictionary" definition of an element as: "a substance which cannot be divided into a simpler form by known methods" and educational institutions' lists of elements generally align with this definition as well.