单项选择题
A.1KHz频率处的声压级为63dB B.900-1120Hz频率范围内的声压级的和为63dB C.710-1400Hz频带范围内的声压级的和为63dB D.333Hz频率处的声压级为63dB
A.7 B.8 C.9 D.10
A.250-500Hz,400-500Hz B.500-1000Hz,500-630Hz C.355-710Hz,430-560Hz D.430-560Hz,355-710Hz