学习 about how some 声 are 高 and others 低

What is Pitch?

The 相对 height of a 声波 范围（排列） from 低 to 高

A few pitches
Here are a few different 音高 Each of these are at a different height

The three 音高 in this soundfile above might be 描述 respectively as

1 低
2 媒介 and
3 高


Beyond 传统 观念 of Pitch

In 传统 樂/乐 记谱法 音高 is indicated along the vertical 轴 of the stave The 音高 of 声 can be quickly 描述 as being 低 middle or 高 pitched But we can split this into as many registers as are required e g Low-Medium High-Medium etc

Pitched sounds

正弦 Tone
This is a pitched 声波 A 正弦 音 is the most simple pitched 声波

You can see the simplicity and the focus of this 声波 能量 by looking at a 频谱图 of the 声波

Of course 不 every 声波 has a clear 音高 Many noisy 质地（纹理、织体） are spread across the 音高 register and do 不 have a 特定 主要 focus

Noisy sounds

White noise
A noisy 声波 which has no clear 音高


Fact

音高 can also be 描述 in 术语 of 频率

频率 is a 科学 术语 that 描述 音高 just as H2O is a 科学 术语 that 描述 water

A 高 频率 声波 has a 高 音高 while a 低 频率 声波 has a 低 音高


多 音高

Some 声波 源 produce more than one 音高 either at the same 时间

Either at the same time

North American Train Horn
This single horn 声波 包含 多 音高 playing at the same 时间

Or one after the other

Birdsong
This birdsong is a short 旋律 of different 音符 跟随 on from one another Because the 音符 happen in quick succession we 听 this as a single 姿态

Fact

When we examine individual 声 in 细节 we can discover that 声 are often made up of individual 音高 元素 For more 信息 see 复杂 声波 波

This is a 频谱图 of a 三角 波 A single 三角 波 is itself made up of many individual 音高 we see them here as stripes


What Causes Pitch?

Pitched 声 are caused by regular 共鸣 If an 对象 vibrates in a regular way moving back and forth smoothly then it will 创作 a pitched 声波 The less regular the 声波 vibrates then the noisier it is

We can 经验 this by rubbing our finger around the damp rim of a glass to make it sing

活动

Singing Glass

Instructions

•Ask someone at home if you can borrow a wine glass or any glass with a stem
•Pick a wine glass that makes a good 環/环 when you tap it
•Wet your finger and the rim of the glass
•Then while holding the glass firmly with your non-writing hand take the first finger of your writing hand and rub it smoothly and steadily around the rim of the glass

预测 Results

•If you are able to make 平滑 and steady regular motions around the rim the glass should begin to sing 创作 a pitched 音符
•If you move your writing hand in an irregular way around the glass then no 音高 will be 创作

Why is a 音高 created?

The 平滑 and steady 运动 of the hand around the rim of the glass causes the glass to 振动 in a regular way and thus to produce a pitched 声波


Extra

By changing the 级 of liquid in the glass it is 可能 to change the 音高
This is because the liquid dampens the 共鸣 where it touches the glass thus changing the amount of the glass which is 自由 to 振动

The more liquid in the glass the smaller the 表面 that can 振动 and the 较高 the 音高 产生

This 过程 is 类似 to the way in which changing the 长 of a string on a guitar of violin will change the 音高 made shorter string = 较高 音高

Changing the Pitch

Using 技术 it is 可能 for us to change the 音高 of 声

The 过程 is known as 音高移位 or 转换 This 技能 is often used in pop 樂/乐 or cartoons to 创作 高 pitched voices

For 例如

Normal Voice
This is the 原始/原创 unedited 錄/录

Pitch-shifted Voice
This is the pitch-shifted version in which the 声波 has been 增 in 音高

This can be a really useful 效果（效应） to 变形 and develop 声 For 例如 see 变形 for an 例如 of the 用 of 音高 移位/偏移 in 创作 变形


作曲 Tip

Try to 用 a 混合 of 高 媒介 and 低 pitched 声 in your 作曲

Using a 范围（排列） of different 音高 allows you to fill up the whole 声波 范围（排列） and provide a much richer 声景观（声景）


Extra

Changing 音高 over 时间

Using 自动化 it is 可能 to 变形 the 音高 移位/偏移 of a 声波 over 时间 This can allow you to 创作 glissandi and dynamic/changing 变形

音高 移位/偏移 Clock
The amount of 音高 移位/偏移 增 over time

Find out more about how the 音高 移位/偏移 functionality 作品 within 作曲 With 声


聆 Challenge

听 out for pitched 声 around you

•How would you 描述 their pitch?
•Are they high/low
•changing/constant
•or are there 多 pitches?


百科
音高 as Property

The 相对 height of a 声波 范围（排列） from 低 to 高 A pitched 声波 will 包含 relatively focused 频谱 能量 and it is this characteristic that enables pitched 声 to be distinguished from noisy 声 see 噪

学习 More
Click Here to 探索 the 属性 of 音高 in more 细节

音高 as 声波 Type

对象 that 振动 in a more ordered fashion produce 声 that we 描述 as pitched This is because the 声 产生 包含 a greater focus of 声波 波 能量 with 频率 concentrated into 窄 频带 These concentrations of 声波 波 能量 at certain 频率 are called 分音