reference sound pressure

例句：

1. 1.The sound pressure level of the recording is measured in decibels.
   录音的声压级以分贝为单位测量。
2. 2.The sound pressure level of the recording is measured in decibels.
   录音的声压级以分贝为单位测量。
3. 3. The sound pressure level of the recording is measured in decibels.
   录音的声压级以分贝为单位测量。