A 滤器 is a 处理 工具 which can 改 the 相对 balance of 频率 within a 声波

What is a filter?
A 滤器 changes the 频率 makeup of a 声波 by 制作 parts of it weaker

滤器 allow you to focus on parts of a 声波 that are of interest to you or to take away parts that you don’t like such as 噪 or ‘hiss’

As we learnt in 音高 and 声景观(声景) 樂/乐 声 are often made up of many different 频率 parts

By viewing the 频谱图 of a 声波 it is easy to see the different 频率 parts which make up that 声波

Using 滤器 we can change the balance of these 频率 parts removing some to make others stand out

滤器 in Action
Below are a some 声 which have been 滤

Can you 听 the difference between the 声 before and after filtering?

What has changed?

滤器 Properties
滤器 have two 主要 控制

频率 the 频率 at which the 滤器 operates
品质 the width and 形状 of the 滤器 窄 or wide / gentle or steep

By altering these 控制 we can change the 输出 声波 as demonstrated in the 视频

滤器 Types
There are 几个 种类 of 滤器 and each creates a different 种类 of 效果(效应)

Each 种类 is explained below with the same 原始/原创 声波 being transformed by the different 滤器

原始/原创 声波 - Keys And Door
This 声波 包含 many different parts the 高 jangle of they keys and the 低 thud of the door closing 听 and compare it with the 跟随 滤 versions of the same 声波

低通 filter

Allows all 频率 较低 than its cut off point to 通过 for 例如 if the cut-off 频率 is set at 500 Hz(he zi)/赫兹 赫兹(he zi) all of the 频率 over 500 赫兹(he zi) will disappear Does 不 allow any 较高 频率 to 通过 Best used to remove 讨厌 高 声 or to 突出 only the 低 频率 portions of a 声波

低通 Filter
You can 听 only 低 频率 all of the key jangles have been removed

作曲 Tip
低通 滤器 can be useful when we want to 突出 only the 贝斯 频率 of a 声波

高通 filter

Allows all 频率 较高 than its cut off point to 通过 Does 不 allow any 较低 频率 to 通过 Best used to remove 讨厌 贝斯 声 or to 突出 only the 高 频率 portions of a 声波

高通 Filter
All 低 parts of the 声波 have been removed Leaving only the jangling of the keys We no longer 听 the 低 thump of the door closing

作曲 Tip
高通 滤器 can be very useful for removing 低 背景 噪 like the rumble of traffic from 录音

带通 Filter


Allow one 带/乐队 of 声波 to 通过 through Best used to 突出 频率 of 声波 in a 特定 area The 品质 of the 滤器 will 影响 its width

带通 Filter
Only a 窄 带/乐队 of 声波 is allowed through the 滤器 We lose both the 高 and 低 频率 parts of the 声波

作曲 Tip
Being able to focus on one 特定 are of the 声波 allows us to 突出 a 特定 方面 that might be 独特

带阻 Filter

This 滤器 will 不 let a certain 带/乐队 of 声波 to 通过 through Best used to remove 声 at a 特定 频率 The 品质 of the 滤器 will 影响 its width

带阻 Filter
In this 例如 only a 窄 带/乐队 of 声波 is removed We can see this 清楚 in the 频谱图 and we 听 that this middle part of the 声波 is missing

作曲 Tip
The 带/乐队 reject 滤器 can be useful for removing hum or 噪 that fall within the mid 频率 范围(排列) of a 錄/录

Fact
The 贝斯 and treble 控制 on your 立体声 or car 无线电 are 滤器

When to 用 filters?
滤器 allow us to 变形 the 频率 makeup of 声 They can therefore be very useful to us

We can 用 滤器 to balance 声 removing very 响 portions of the 频率 范围(排列) or 增强 areas of interest which are quiet

合并 with 自动化 滤器 can be very useful in 创作 姿态 and a 感觉 of 动作

We can 用 a 滤器 Sweep to draw people’s attention to different portions of 声波 and to cary the 听众 on a 旅程 into 声

Activity
Load up a session in 作曲 With 声 and begin to 探索 滤器 yourself

Try to make 用 滤器 in a 作曲


百科
A 滤器 changes the 频率 makeup of a 声波 by 制作 parts of it weaker 滤器 allow you to focus on parts of a 声波 that are of interest to you or to take away parts that you don't like such as 噪 or 'hiss'

Some 滤器 also known as Equalisers can make parts of the 声波 stronger

Controls

滤器 have two 主要 控制
•Frequency the 频率 at which the 滤器 operates
•Quality the width and 形状 of the 滤器 窄 or wide / gentle or steep

滤器 Types

There are 几个 种类 of 滤器

低通 滤器 – Allows all 频率 较低 than its cut off point to 通过 for 例如 if the cut-off 频率 is set at 500 Hz(he zi)/赫兹 赫兹(he zi) all of the 频率 over 500 赫兹(he zi) will disappear Does 不 allow any 较高 频率 to 通过 Best used to remove 讨厌 高 声 or to 突出 only the 低 频率 portions of a 声波

•High-pass 滤器 – Allows all 频率 较高 than its cut off point to 通过 Does 不 allow any 较低 频率 to 通过 Best used to remove 讨厌 贝斯 声 or to 突出 only the 高 频率 portions of a 声波

•Band-pass Filter
 – Allow one 带/乐队 of 声波 to 通过 through Best used to 突出 频率 of 声波 in a 特定 area The 品质 of the 滤器 will 影响 its width

•Band-reject Filter
 – Will 不 let a certain 带/乐队 of 声波 to 通过 through Best used to remove 声 at a 特定 频率 The 品质 of the 滤器 will 影响 its width

Fact
The 贝斯 and treble 控制 on your 立体声 are 滤器