5.2.1 听觉_视频在线视频

我们人所接受的这些声音刺激 它有特定的范围
The sound stimuli we receive have a specific range

有些声音我们听不到 比如频率太长的超声波
Some sounds we can't hear such as its frequency is too long ultrasound

如果频率太低呢也听不到
If the frequency is too low to hear

我们所能听到的这个频率是16—20000赫兹这一个范围
the frequency we can hear is in the range of 16-20 000 hertz

超过20000赫兹的就是超声波
If the frequency is more than 20 000 hertz,it is ultrasound

低于16赫兹声音太慢 也听不到
If the frequency is lower than 16 hertz,the sound is too slow to hear

那么 赫兹大家都知道这就是频率
Everyone in Hertz knows this is the frequency

这是我们所能够听到的声音的范围
which is the range of sounds we can hear

横轴是频率 赫兹
The transverse axis is frequency Hertz

纵轴叫声压或者叫声强 就是它的强度
and the longitudinal axis is called sound pressure or sound intensity

频率应该是200到3200赫兹 这个就是我们语言说话所在的一个范围
which is its strength Frequency should be 200 to 3200 hertz which is a range of our language

这另外一个频率是自然界的其他声音 我们也能够听到
The other frequency is other sounds of nature and we can hear them

除了这一个范围的我们就听不到了
except for this range

这里有几个概念
There are several concepts here

第一个听阈 就是最小的声强 0.001的样子 最小的声强
The first threshold is the minimum sound intensity about 0.001

那么还有最大的声强 最大的可听阈
Then there is the maximum sound intensity and the maximum audible threshold

就在这上面 声强是5000左右
Just above that the sound intensity is about 5000

这个听阈呢就是两个曲线的一个面积
This threshold is an area of two curves

这个声强这里用声压表示的就是一个意思
This sound intensity here is expressed by sound pressure

声强是怎么表示的呢？
How is the sound intensity expressed?

就是可听到的最小声强
It is the minimum sound intensity that can be heard

我们每个人有一个可听到的最小声强
Each of us has a minimum sound intensity that can be heard

声音的强度 除以它实际的声音的强度
The intensity of the sound divided by the actual intensity of the sound

取一个对数 这就是贝尔
takes a logarithm.This is Bell

那一贝尔等于十分贝
That Bell is equal to ten decibels

我们通常所说的都是分贝 分贝也是一个声强的单位
What we usually call decibels is also a unit of sound intensity

下面我们就来看听觉器官 耳朵的一个结构 我们都比较清楚
Now let's look at the auditory organs a structure of the ear

可以把整个耳朵分为
We all know that the whole ear can be divided into three parts:

外耳中耳和内耳三部分
the outer ear、the middle ear and the inner ear

外耳可以是这个耳廓 外耳道和骨膜
The outer ear can be the auricle the ear canal and the periosteum

耳廓有什么用？
What's the use of the auricle?

它长成这样一个窝窝的形状 来一个声音它可以收集
It grows into the shape of such a nest to a sound it can collect

外耳道它很神奇 声音经过这个外耳道
the external auditory canal it is very magical.Sound through the external auditory canal

它能产生共振 强度会更强
it can produce resonance the intensity will be stronger

而且它产生共振的频率只是对我们人所听到的声音的频率
And the frequency of resonance is only the frequency of the sound we hear

特别对语言的频率
especially the frequency of language

在外耳道里面产生的振强强度更高
which produces stronger vibration intensity in the external auditory canal

这是耳廓和外耳道
This is the auricle and external auditory canal

它可以通过共振增加声强
It can increase sound intensity through resonance

第二个是中耳 就是骨膜里面的这一部分
The second is the middle ear which is part of the periosteum

我们看这个模拟图 把它放大就是这个样子
Let's look at this simulation and zoom it in like this

这个是骨膜 跟骨膜连着的有三个骨头
This is the periosteum.There are three bones connected with the periosteum

三个骨头对产生听觉作用很关键
Three bones are crucial for auditory production

一个骨头是附在骨膜上的 骨膜一震动这个骨头也震动
A bone is attached to the periosteum.When the periosteum vibrates the bone also vibrates

这个骨头的震动带着另外两个骨头的震动
The vibration of the bone brings the vibration of the other two bones

这个骨头叫作锤骨 像一把锤子一样 锤在这个骨膜上
The bone is called the mallet which is hammered on the periosteum like a hammer

跟骨膜相连的是砧骨 就好比一块砧板 连着
The anvil is connected to the periosteum just like an anvil

跟砧骨相连的是镫骨
The stapes are connected to the incus

这三块骨头我们统称为听小骨
These three bones collectively known as the auditory ossicles

是内耳里面很重要的结构
are important structures in the inner ear

跟锤骨相连的是骨膜
The periosteum is connected with the malleus

和骨膜相连的是卵圆窗
and the oval window is connected with the periosteum

卵圆窗的震动就会影响后面耳蜗的震动 这是关键
The vibration of the oval window will affect the vibration of the cochlea behind which is the key

下面还有一个圆窗 这五个就构成了中耳
There is also a round window below.These five make up the middle ear

总之它的作用就是把声波的震动变成机械震动
In short its function is to transform the vibration of sound waves into mechanical vibration

传递给听小骨
which is transmitted to the auditory bones

还有一个骨膜 我们知道骨膜很关键
There is also a periosteum.We know that periosteum is very important

它是一个半透明的膜
It is a translucent membrane with an area of 50-90 mm2

面积有50~90mm2 频响较好 失真度较小
It has good frequency response and low distortion

让声音都能保持一个它原来的频率
so that the sound can maintain its original frequency

这是中耳主要由骨膜和听小骨组成 我们看听小骨
This is the middle ear mainly composed of periosteum and ossicles.Let's look at the small bones

就是刚才的这三块骨头 下面这个红色的模拟图 红色的是骨膜
which are just the three bones The next red simulation is the periosteum

这个大的是锤骨 砧骨 这个是镫骨
The big one is the hammer the incus the stapes

骨膜会拉动这个锤骨 骨膜的震动 就会影响锤骨的震动
this periosteum will pull the malleus,periosteum vibration will affect the vibration of the malleus

锤骨一震动 以杠杆为轴的话这一头震动 这一头就会打动中间这个砧骨的震动
malleus vibration with the lever as the axis this head will move the vibration of the incubator in the middle

砧骨的震动就会拉动镫骨
The vibration of the incus will pull the stapes

跟镫骨连着的这个卵圆窗就会拉动这个卵圆窗机械震动
and the oval window connected with the stapes will pull the oval window mechanical vibration

所以骨膜的震动要大一些 听小骨的震动要小一些
Therefore the vibration of periosteum is larger and the vibration of small bones is smaller

这是保护卵圆窗怕它的震动过大 造成损伤
This is to protect the oval window from excessive vibration and damage

骨膜的有效震动面积和卵圆窗的面积之比是17:1
The ratio of the effective vibration area of periosteum to the area of oval window is 17:1

声音的传递使声压增强1.3倍
The ratio of the effective vibration area of periosteum to the area of oval window is 17:1

最后卵圆窗的压强比骨膜的压强是22:1
The pressure of oval window is 22:1 than that of periosteum

卵圆窗的压强要更大一些
The pressure of oval window is higher than that of periosteum

所以它活动的距离比骨膜要小很多
So the distance of movement of oval window is much smaller than that of periosteum

但是它承受的压强要比骨膜大多了
but the pressure it bears is much greater than that of periosteum

这是一个平衡 你距离越小 力气越大
This is a balance The smaller your distance the stronger your strength

还有一个结构是咽鼓管
There is also a structure called the eustachian tube

既然是咽鼓管 它应该是通着空气可以上去的
Since it is the eustachian tube,it should be able to go up through the air

我们看咽鼓管的作用
We look at the function of the eustachian tube

它主要是和咽腔相通的一个管道 所以叫咽鼓管
which is mainly connected with the pharyngeal cavity,so it is called the eustachian tube

骨膜和咽腔的一个管道 在鼻咽部是关闭的
A conduit in the periosteum and pharynx is closed in the nasopharynx

只有吞咽打哈欠和打喷嚏的时候才会开放
and will only open when yawning and sneezing are swallowed

它的主要作用就是调节骨膜两侧气压的平衡
Its main function is to regulate the balance of air pressure on both sides of the periosteum

保持骨膜的正常位置形状和震动的性能
maintain the normal position and shape of the periosteum and the performance of vibration

这就是咽鼓管的作用
which is the role of the eustachian tube

刚才我们到了中耳呢还是机械的
Just now the transmission of my middle ear is still mechanical

外耳的是声音的能量 通过中耳转变为机械的以后
The outer ear is the energy of sound.After the middle ear is transformed into mechanical

最终我们是要变成神经冲动我们才能够这种感觉
we finally have to become nerve impulses to feel this way

变成神经冲动的结构呢就是内耳
The structure of the nerve impulse is the inner ear

内耳最重要的一个就是耳蜗
The most important part of the inner ear is the cochlea

我们看在这 在我们三根小骨 这里没有了 在这个地方
We see here

接在这个地方是卵圆窗 这里是耳蜗就像是蜗牛一样 蜗牛的壳一样卷上去
next to this place is the oval window.Here is the cochlea which rolls up like a snail's shell

如果我给一个纵剖面给剖开 就是这么一个样子 里面大概有三个腔
If I cut a vertical section,it's like this.There are about three chambers in it

一个腔叫前庭阶 一个叫鼓阶 第三个腔叫蜗管
One is called vestibular step the other is drum step and the third is called pit tube

大家可以想象一下 如果剖开的话 这里是管子的横截面
You can imagine that if you cut it open here is the cross section of the tube

它如果是一个管子的话是这样绕着的 这是它的三个腔
If it's a tube,it's wrapped around like this.This is its three chambers

那么前庭阶这个他们是通着的是一根管道
So the vestibular stairs which are connected by a pipe

前庭阶和鼓阶的液体它们是相通的
are connected to the fluid of the vestibular stairs and the drum stairs

它们通的地方在蜗孔相连 在这里他们连起来了
Where they connect is in the hole

前庭阶和鼓阶液体是相连的 蜗管和他们是不相连的 分开的
The vestibular and tympanic stairs are interlinked and the pit and the tympanic stairs are not connected

下面我们看一看它这个声音最终是怎么到这个听神经的
Now let's see how the sound finally reaches the auditory nerve

刚刚我们讲了前庭阶 鼓阶 蜗管在这个地方叫作柯蒂氏器
Just now we talked about the vestibular step the drum step and the pit here is called the Corti's organ

这个柯蒂氏器在卵圆窗的震动以后呢
After the vibration of the oval window

它会有一些特殊的结构 能够感受得到这种神经信号
the Corti's apparatus has some special structures which can sense the nerve signals

我们看这样的结构是什么样的
Let's see what the structure is like

这个是三个半规管 这个是耳蜗
This is three semicircular canals and this is the cochlea

如果把耳蜗取一截下来 切一节下来
If the cochlea is cut off and cut into sections

就是刚才的三个腔 前庭阶 鼓阶 这里是蜗管
it will be the three cavities vestibular step and tympanic step just now.Here is the pit canal

蜗管下面这一块 虚线串起来的这一块 这个就是柯蒂氏器
the one under the pit canal the one with dotted lines This is the Corti's organ

柯蒂氏器放大它就是这样一个样子 上面的叫膜盖
The Corti's organ magnifies it like this.The upper one is called the cap membrane

下面的叫基底膜
and the lower one is called the basement membrane

基底膜就有很多的神经纤维 那它机械能使如何转变为神经冲动的呢？
There are many nerve fibers in the basement membrane How can it mechanically transform into nerve impulses?

在于连着的这个 这些像绒毛一样的 叫作听毛 这些听毛的作用就是很关键
These hair-like ones are called auditory hair These auditory hair functions are crucial

我们来看一看 首先蜗管是一个导管 里面充满了内淋巴
Let's take a look First of all the pit is a catheter which is filled with lymphoid

前面说前庭阶和鼓阶它们是相通的 不是一个管
The vestibular and tympanic steps are connected not a tube

内淋巴一个特点就是钠离子的含量很低 钾离子的含量很高
One of the characteristics of perilymph and endolymph is that the content of sodium ion is very low and the content of potassium ion is very high

这是跟它外侧壁这些细胞的细胞膜上的钠钾泵有关
This is related to the sodium and potassium rods on the cell membrane of these cells in its lateral wall

它把钾离子放到淋巴内
It puts potassium ions in the lymph

放回这个细胞 放到淋巴液的钾离子更多
It puts potassium ion into the lymph and there are more potassium ions in the lymph

放回这个细胞 放到淋巴液的钾离子更多
It puts potassium ion into the lymph and there are more potassium ions in the lymph

外面的钾离子更多 它的正电荷越多
The more positive charges it has outside the more potassium ions it has

我们知道蜗管里面的这些内淋巴钾离子含量很高 带有更多的正电荷
We know that these lymphoid potassium ions in the pits are very high and have more positive charges

我们看柯蒂氏器 它是位于基底膜上的结构
Let's look at the Corti's organ which is a structure located on the basement membrane

下面这一层就叫作基底膜
The next layer is called the basement membrane

主要由内外毛细胞 支持细胞及膜盖等构成
which consists mainly of inner and outer hair cells supporting cells and cap membranes

这些都是支持细胞 支持膜盖
These are supporting cells that support the cap

这个毛细胞每个毛细胞的顶部都有数百条排列整齐的听毛
At the top of each hair cell there are hundreds of neatly arranged auditory hairs

这些较长的听毛埋于盖膜中 这些都埋于膜盖中
These long auditory hairs are buried in the capsule

螺旋器是浸浴在内淋巴中
The spiral apparatus is immersed in the endolymph

这个是螺旋器 是泡在内淋巴中的
and this is the spiral apparatus which is soaked in the endolymph

这样它的离子就可以在膜内细胞内进行交换
In this way,its ions can be exchanged within the membrane cells

柯蒂氏器贯穿耳蜗全长 这里有柯蒂氏器
The Corti organ runs through the whole length of the cochlea.Here is the Corti organ

整个这一环都会有柯蒂氏器 这一圈又称螺旋器
The whole ring will have the Corti organ.This circle is also called the spiral organ

我们来看它是怎么样来完成它的转化为神经冲动功能的
Let's see how it can accomplish its transformation into nerve impulse function

刚刚讲到这个是基底膜
Just mentioned that it is the basement membrane

基底膜是由辐射状的纤维丝 大概由两万到三万根构成
The basement membrane is composed of radial filaments consisting of about 20000 to 30000

这些听毛的宽度越接近窝底就越窄
The nearer the width of these auditory hairs is to the bottom of the fossa

越接近窝顶就越宽
the narrower they are to the top of the fossa

每一根听丝上都有一根柯蒂氏器
There is a Cordy's organ on each wire

大家看 这个就是耳蜗 这是耳蜗的基底膜
You see,this is the cochlea,this is the basement membrane of the cochlea

基底膜上就有听毛细胞
there are auditory hair cells on the basement membrane

那么这是底部 底部的听毛细胞是很窄的
then this is the bottom,the bottom of the auditory hair cells is very narrow

顶部的听毛细胞是很长的
the top of the auditory hair cells is very long

很窄的就接受频率很高的频率声音 很长的就接受频率很低的频率声音
very narrow to receive high frequency sound very wide to receive very low frequency sound

基底膜的宽度和不同频率的
The width of the basement membrane and the sound waves of

声波他们能够产生最大的振幅
different frequencies can produce the maximum amplitude

这个基底膜就能感受到柯蒂氏器的声音频率
the basement membrane can sense the sound frequency of the organ

基底膜最终会引起它这一个地方离子运动产生的神经冲动
which eventually triggers nerve impulses generated by ionic movement in this part of the cochlea