密集气孔 meaning in Chinese

concentrated porosity
porosity

The echo of single hole was high , its front was steep edge ; the echo of dense hole was connected and uneven ; the echo of crack was high and keen - edged , the bottom echo was decline in some certain ; the echo root of bird ' s net had some small wave followed
单个孔洞反射回波高，前沿较尖锐；密集气孔回波参差不齐，根部互相连接；裂纹回波高而尖锐，底波有所下降； “鸟巢”缺陷的反射波根部有若干小波峰出现。