sounding board
noun [ C usually singular ] uk/ˈsaʊn.dɪŋ ˌbɔːd/ us/ˈsaʊn.dɪŋ ˌbɔːrd/
（检测新想法或建议是否可行的）测试人（或班子）
a person or group of people that you use to test something such as a new idea or suggestion to see if they will accept it or if they think it will work