Specifically speaking, 聲 is concentrated on the auditory production, while 音 is focused on the auditory perception, although both can refer to the sound (Hong and Huang, 2004;Hong and Huang, 2005).
through studying the synaesthetic usages of this pair of near synonyms, not only can we test whether synaesthesia is sensitive to the semantic dichotomy of production and perception, but also we can examine the relationship between synaesthesia and cognition.