《发声和传声》是《自然常识》第三册的第十四课。课文首先通过铜锣发声实验,说明声音是由物体振动发生的,固体、液体、气体振动都能发声。接着通过空气振动实验,说明声音是靠媒介物来传播的,然后讲到声波的概念和回声的产生。本课可分为2课时来讲。第一课时讲发声和传声,第二课时讲声波和回声。重点是振动发声和声波概念。 Voices and Sounds is the fourteenth lesson of Volume Three of The Natural History. The text first gongs experiments, indicating that the sound is generated by the vibration of objects, solid, liquid, gas vibration can sound. Then through the air vibration experiments, the sound is transmitted by the media, and then talked about the concept of sound waves and echo generation. This lesson can be divided into 2 classes. The first class speaks and transmits sound, the second class speaks sound and echo. The emphasis is on vocalization and sound wave concepts.