G11S Phy Ch3,4 Reception of sound Vid 2 of 3 En 20 21
Summary
TLDRThis educational video explores the reception of sound, contrasting it with the emission of sound from the first part. It explains the working of a loudspeaker, an electro-acoustic converter, and a microphone, an acousto-electric converter. The video also delves into the anatomy of the human ear, detailing how it converts sound vibrations into electrical signals. It discusses the audible frequency range of the human ear, from 20 Hz to 20 kHz, and touches on the applications of ultrasounds, such as in sonar technology for depth measurement and medical imaging.
Takeaways
- 🔊 Sound is a longitudinal mechanical wave generated by the vibration of an object in a material medium.
- 📣 A loudspeaker is an electro-acoustic converter that uses magnets, a coil, and an elastic membrane to convert electrical signals into sound waves.
- 🎙️ A microphone is an acousto-electric converter that converts sound vibrations into electrical signals, with components similar to a loudspeaker.
- 👂 The human ear is a complex sound receiver with three main parts: the external ear, the middle ear with the eardrum and ossicles, and the internal ear with the cochlea.
- 🎵 Sound waves received by the ear are transformed into nerve messages as electric signals, which are then processed by the brain.
- 🚫 The human ear can hear sounds within the frequency range of 20 Hz to 20 kHz, known as audible frequencies.
- 🔉 Sounds below 20 Hz are called infrasounds, and those above 20 kHz are called ultrasounds, which are inaudible to the human ear.
- 🏊 Ultrasounds have practical applications in echolocation, such as in sonar technology used for depth measurement and object detection underwater.
- 🌊 Echo sonar works on the principle of sending ultrasonic waves and measuring the time it takes for their echo to return, allowing for the calculation of distances.
- ⏱️ The depth of water can be determined using the speed of sound in water and the time interval between the emission and reception of an ultrasound's echo.
Q & A
What is the main topic of the lesson described in the transcript?
-The main topic of the lesson is the reception of sound, focusing on how sound is received and converted into electrical signals by devices like microphones and the human ear.
What are the main parts of an electrodynamic loudspeaker?
-The main parts of an electrodynamic loudspeaker are magnets, a coil, and an elastic membrane.
How does a loudspeaker function when connected to an AC source?
-When connected to an AC source, an electromagnetic force is created in the loudspeaker, causing the coil to vibrate. This vibration is transferred to the elastic membrane, which then emits sound waves.
What is the speed of sound in solids, and why is it relevant?
-Sound is fastest in solids because it is a mechanical wave that requires a medium to propagate. The speed of sound in solids is not explicitly mentioned in the transcript, but it is generally faster than in liquids or gases.
What is a microphone and how does it relate to the concept of an electro-acoustic converter?
-A microphone is a sound receiver that converts sound vibrations into electrical signals, making it an acousto-electric converter. It is related to the concept of an electro-acoustic converter because it transforms acoustic energy into electrical energy.
What are the main parts of a microphone?
-The main parts of a microphone are the elastic membrane, the coil, and the magnet.
How does a microphone convert sound vibrations into electrical signals?
-A sound wave causes the elastic membrane of the microphone to vibrate. This vibration is transferred to the coil, which moves within the magnetic field, inducing an electrical current due to electromagnetic induction.
What are the three main parts of the human ear?
-The three main parts of the human ear are the external ear, the middle ear, and the internal ear.
How does the human ear process sound waves?
-Sound waves are received by the external ear, causing vibrations that are transmitted to the eardrum and then to the ossicles in the middle ear. These vibrations are then sent to the internal ear, where auditory cells convert them into nerve messages as electric signals.
What is the range of audible frequencies for the human ear?
-The human ear can hear frequencies between 20 hertz and 20 kilohertz (20,000 Hz).
What are the three regions of the audible frequency range?
-The audible frequency range is divided into deep sounds (20 to 500 Hz), medium sounds (500 to 3,000 Hz), and sharp sounds (3,000 to 20,000 Hz).
What is the principle behind the use of sonar, and how is it applied?
-The principle behind sonar is the reflection of ultrasounds. It is applied by sending a burst of ultrasonic waves towards a surface and measuring the time it takes for the echo to return. The depth or distance can be calculated using the speed of sound and the time interval.
How is the depth of water measured using sonar in the example provided?
-In the example, a sonar emits an ultrasound and receives its echo after 400 milliseconds. Using the formula v = (2d)/(∆t), where v is the speed of sound in water (1500 meters per second), the depth d is calculated to be 300 meters.
Outlines
🔊 Understanding Sound Reception and Loudspeakers
This section delves into the reception of sound, following the study of sound emission. It explains that sound is a longitudinal mechanical wave generated by object vibrations. The main components of a loudspeaker are identified as magnets, a coil, and an elastic membrane, which together convert electrical signals into sound waves. The speed of sound varies with the medium, being fastest in solids. The objectives include explaining the operation of a microphone and the range of audible frequencies for the human ear. A microphone, an acousto-electric converter, is described as having an elastic membrane, a coil, and a magnet, similar to a loudspeaker, but it converts sound vibrations into electrical signals through electromagnetic induction. The human ear, a superior sound receiver, is anatomically and functionally described, highlighting its ability to convert sound vibrations into nerve impulses. The audible frequency range for humans is detailed, with infrasound and ultrasound defined as non-audible sounds below and above this range, respectively.
🛰 Applications of Ultrasound in Sonar and Echolocation
This part explores the practical applications of ultrasound, particularly in echolocation and sonar technology. It discusses how sonar works by sending ultrasonic waves and measuring the time it takes for the echo to return, allowing for the calculation of distances such as the depth of water. The principle of sonar is explained through the formula relating wave speed to the time interval between emission and reception of the wave. An example calculation is provided, where a sonar emits an ultrasound and receives its echo after a certain time, leading to the determination of water depth. The section concludes with a summary of the chapter's content and a thank you note to viewers.
Mindmap
Keywords
💡Emission of Sound
💡Reception of Sound
💡Longitudinal Mechanical Wave
💡Electrodynamic Loudspeaker
💡Electroacoustic Converter
💡Microphone
💡Audible Frequencies
💡Human Ear
💡Echolocation
💡Sonar
Highlights
Sound is a longitudinal mechanical wave produced by the vibration of an object.
The main parts of an electrodynamic loudspeaker are magnets, coil, and elastic membrane.
A loudspeaker is an electro-acoustic converter that converts electrical signals into sound.
The speed of sound varies depending on the medium and is fastest in solids.
A microphone is an acousto-electric converter that converts sound vibrations into electrical signals.
The main parts of a microphone are the elastic membrane, coil, and magnet.
Sound waves cause the elastic membrane of a microphone to vibrate, inducing an electric current.
The human ear is a sound receiver that is unmatched by any microphone.
The ear consists of the external ear, middle ear, and internal ear.
Sound waves received by the ear are transmitted as nerve messages as electric signals.
The human ear can hear frequencies between 20 Hz and 20 kHz.
Sounds with frequencies below 20 Hz are called infrasounds, and above 20 kHz are called ultrasounds.
The audible frequency range is divided into deep, medium, and sharp sounds.
Ultrasounds are used in echo sonar for determining the depth of the sea or detecting submarines.
Ecography is a medical technique using ultrasounds to obtain images of body organs.
Echo is used in exploration of fossils, patrol, and geology for searching oil and gas.
The principle of a sonar is based on the reflection of ultrasounds and measuring the time interval between emission and reception.
The depth of water can be determined using the speed of ultrasound and the time interval between emission and reception of its echo.
Transcripts
[Music]
in the first part of this lesson we have
studied about emission of sound today in
part 2 we are going to learn more about
reception of sound
but first let's remember
sound is a longitudinal mechanical wave
produced by the vibration of an object
in a material medium
the main parts of an electrodynamic
loudspeaker are magnets coil and elastic
membrane
a loudspeaker is an electro acoustic
converter what about the functioning of
a loudspeaker
when an ac source is connected to the
loudspeaker then an electromagnetic
force is created causing the vibration
of the coil
being connected to the coil the membrane
also undergoes vibrations that lead to
the emission of the sound waves
the speed of sound depends on the medium
of propagation and sound is fastest in
solids since it is a mechanical wave
the objectives of this part are
explain how a microphone works and
indicate the range of audible sounds
heard by the human ear
now let's start with part 2 reception of
sound
one of the most popular receivers of
sound is the microphone it is a sound
receiver that converts the sound
vibrations detected into electrical
signals
therefore it is called an acousto
electric converter
before explaining the functioning of the
microphone it's important to list its
main parts which are the elastic
membrane the coil and the magnet
these parts are common between the lock
speaker and the microphone
now let's see how do these parts
interfere and the functioning of the
microphone a sound wave transmitted by
air particles sets the elastic membrane
of the microphone in vibration
the membrane vibrates with the same
frequency as the wave
being fixed to the membrane the coil
vibrates between the poles of the magnet
and the current is induced
due a phenomena which is called the
electromagnetic induction
therefore sound vibrations received by
the membrane are then transformed into
electric signals the ear the organ of
hearing is a sound receiver which is
unmatchable by any microphone
is there an analogy between the
operation of these two receivers the ear
has three main parts the external ear
formed of the article
which leads to the auditory canal
the middle ear separated from the
external ear by the eardrum and is
formed of three small movable bones
called the ossicles
the internal ear formed of the cochlea
covered with the auditory cells
how does it function sound waves are
received by the article of the ear where
they produce vibrations these vibrations
are transmitted to the eardrum and then
to the ossicles of the middle ear which
transmits them to the internal ear the
auditory cells of the internal ear
transmit these vibrations in a nerve
message as electric signals
the ear is sensitive to a limited range
of frequencies called audible
frequencies
the human ear can hear a sound of a
frequencies between 20 hertz and 20
kilohertz or 20 000 shirts
the non-audible sounds are called
infrasounds after frequency is less than
20 hertz and they are called ultrasounds
if their frequencies are greater than 20
000 hertz
these sounds having these frequencies
are not heard by a human ear
the audible frequency range is divided
into three regions
first
the frequencies ranging between 20 and
500 hertz are called deep sounds those
between 500 and 3000 hertz are called
medium sounds
and
between three thousands and twenty
thousand hertz are called sharp sounds
one of the most popular and useful
applications of ultrasounds is the echo
sonar which is a technique based on the
echo of ultrasound some applications of
the echo are zoner is a device used in
ships to determine the depth of the sea
or to detect a submarine
the ecography
is a medical technique used to obtain
images of certain organs of the body it
is done without any pain and without
danger
exploration of fossils or patrol
and geology the echo is used in the
search for oil and gas
let's explain the principle of a soner
a zoner is a practical application of
reflection of ultrasounds
its principle is to send a salvo of
ultrasonic waves to the surface to be
studied and then to measure the time
delta t between the emission of these
waves and the reception of its echo
the speed of these waves is equal to the
distance traveled during emission and
reception divided by the time from the
instant of emission to that of reception
and since the distance covered by the
wave is the same distance covered by its
echo then we can say that the speed v is
equal to 2d divided by delta t which is
the time interval between emission and
reception
where the speed v is equal to 1 500
meter per second which is the speed of
sound in the water
let's have a direct application on this
owner
a sonar emits an ultrasound of speed
1500 meter per seconds down a c and
receives its echo after 400 milliseconds
determine the depth of the water at this
toner position
please try to solve this application
first alone then check the solution with
me
the speed is given by the distance
traveled by this wave and its echo
divided by the time interval between the
emission and the reception then it is
equal to 2d divided by delta t
by substitution we will get that the
distance d is equal to 300 meters
therefore the depth of the water is
equal to 300 meters
[Music]
it's the end of this chapter thank you
for watching
[Music]
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