あせる (こえが~)
あせる (こえが~) · aseru (koega~) · JLPT N1 · noun
slice
あせる = 褪せる (fade). 色褪せる = color + fade, so あせる keeps the fade and drops 色
こえが~ means the voice grows faint or loses strength. 褪 is the kanji for fading color, so the same verb works for paint, light, and voice.