The word 心声 (xīnshēng) is a compound noun formed through semantic combination, where the morpheme 心 (xīn), meaning "heart" or "mind", is modified by 声 (shēng), meaning "sound" or "voice". Together, they create a metaphorical meaning that is more than the sum of its parts: the "heart's voice" or the "sound of the mind", which figuratively represents one's innermost thoughts, heartfelt feelings, or true opinions. This formation is a classic example of how Chinese compounds often synthesize concrete characters to express abstract, psychological concepts.