Discover how 声 are 创作 and 理解 the 基（础） 关系 between 对象 their 属性 and the 声 that they make

共鸣 into Sounds
声波 is caused when 对象 振动 An 行为 causes an 对象 to 振动 and these 共鸣 in turn set off 波 and 模式 of 共鸣 in the air

As the sides of the 对象 move back and forth they push and pull the nearby air molecules

The push and pull of 环境 air molecules creates a 波 in the air rippling out from the 颤 对象

Fact
We can see the same 过程 happening in the bath or the sink

If we place our hand in to the water and move it back and forth like the 共鸣 of the 对象 we 创作 波 within the water This is exactly the same 物理 过程 that happens in the 创作 of 声波 only the ripples are formed within the air

听觉 Soundwaves
Our 耳 can 测 soundwave 共鸣 as they cause the 耳 鼓 and other parts of the 耳 to move The 脑 then converts this 运动 in the 耳 鼓 into the 声波 that we 听

声波 共鸣 in the air can also be felt by the rest of our body when an aeroplane or train passes we can sometime feel the 共鸣 in our 胸 The same is true of drums in a 响 rock concert

All 对象 振动 in different ways this is the reason that different 对象 have different 声波 品质

Different 对象 = Different 共鸣 = Different Sounds
All 对象 振动 in their own individual way Some 对象 are just 不 very good vibrators at all for 例如 a rock while others are especially good for 例如 a tight string

The way that an 对象 vibrates when struck directly relates to the 声波 that it produces

Ding of a Glass
听 to the 声波 and compare it with the picture of the glass above What 特征 of the glass give rise to the 声波 that we hear?

Smaller and more 灵活 对象 can produce more 高 频率 波 they 振动 back and forwards at a faster 率 while larger and inflexible 对象 tend to produce 低 频率 波 they 振动 back and forwards at a slower 率

Large Drum
How would you 描述 this sound? How might the 形状 and size of the 对象 relate to its sound?

Extra
Pitched vs Non-Pitched Sounds

Pitched String
When a string is plucked the 共鸣 能量 is focussed up and down the string and so the 声波 波 模式 创作 in the air is also more 控制 and focussed

Non-Pitched Cymbal
When a cymbal is hit the 共鸣 能量 travels erratically through the 对象 leading to an erratic and noisy 波 模式 in the 环境 air

描述 How 对象 Sound
With 经验 we can 学习 to predict the 种类 of 声 that an 对象 will make This can be really useful in helping us to decide which sounding 对象 to pick and 用 within a 作曲

聆 Challenge
There are many 词 that we can 用 to 描述 声 and many of these 词 can also be used to 描述 things that we see Below are a list of 可能 descriptive 词 can you match these 词 to 声 that you have heard?

高 pitched
低 pitched
Short
Long
Rough
Smooth
Changing
Steady
Noisy
Pitched
Sharp
Rounded
Heavy
Delicate
Bright
Dark

描述 this Sound
Which 词 from the list would you 用 to 描述 the 声 in this clip? How many 声 are there? What might be causing the sound?

Activity
Ping Your Ruler

Take a ruler and hold it firmly down onto the desk with the palm of your hand but 制作 sure that one end is hanging over the edge of the desk

Then ‘ping it’ push down and let go the end hanging over the edge of the desk and you should 听 a 声波 This 声波 is 创作 by the back and forth 共鸣 of the ruler

How does the 声波 that you 听 change as you move the ruler?

What happens to the 声波 when more or less of it hangs over the edge?

What if you move the ruler dynamically while it is wobbling ?