The phrase "splitting ears" can be used to describe a very loud and piercing sound. Some synonyms for this phrase could include "ear-piercing," "deafening," "throbbing," or "blaring." These words all convey a similar sensory experience of loudness and intensity, and could be used interchangeably depending on the context. Other possible synonyms might include "screeching," "shrieking," "screaming," or "yelling," depending on the type of sound being described. Regardless of the word choice, the phrase "splitting ears" is a vivid expression that conveys a particularly potent sensory experience.