Final answer:
Henry Cowell's interest in timbre led him to investigate the subjective perception of sound character and quality, tying the study of timbre to the fields of perceptual psychology and acoustics.
Step-by-step explanation:
Henry Cowell's interest in timbre led him to explore the complex and subjective nature of sound perception. His curiosity about the tone quality of different instruments brought his work into the realm of perceptual psychology. Terms such as dull, brilliant, warm, cold, pure, and rich are used to describe timbre, and these descriptions are influenced by high-level brain processes, making it a topic related to psychology and acoustics. Cowell's analysis of timbre reflects an understanding that our perception of these combinations of frequencies and intensities is highly individual. Thus, Henry Cowell delved deeply into how we perceive the distinct character of sounds produced by various musical instruments, enriching our appreciation for the intricate nature of music.