Its special pen and sensor work together using infrared and ultrasonic signals that capture text as it 's written ; they don 't use handwriting recognition .
专用的手写笔和传感器必须搭配使用，通过红外线和超声波信号来捕捉书写轨迹，而不是使用手写识别技术。
These mice were also more likely than control mice to emit ultrasonic squeaks-a type of mouse love song-toward other males .
试验鼠也比对照组发出更多的超声波级别的尖叫声一种对其他雄鼠的情歌。
Nevertheless , they can be difficult and costly to find . Apart from careful visual inspection , techniques like x-rays and ultrasonic probes are also used .
