"Let Sound Serve Humanity" Sound and Environment PPT Courseware 2

Description

"Let Sound Serve Humanity" Sound and Environment PPT Courseware 2

learning target

1. Understand the application of sound knowledge in music and architecture, and understand the application of ultrasound and infrasound in life and modern technology

2. Know the sources of noise and measures to control and reduce noise

Core test points: Application of ultrasound and infrasound, hazards and control of noise.

Preview before class

1. my country's famous "Echo Wall" and "Three-tone Stone" in the Temple of Heaven in Beijing both use the __________ principle.

2. The ______ from the sound source to the two ears is generally different, which results in the ______, ______ and other characteristics of the sound reaching the two ears being different. This is the binaural effect.

3. Sounds with a vibration frequency of ____________ are called ultrasound. As information carriers, ultrasonic waves have been used to study ____________, ____________, etc. Sounds with a vibration frequency of ______ are called infrasound, and the application of infrasound has also penetrated into ______, _____ _and many aspects of people's lives.

4. Noise is very harmful. At present, measures are mainly taken to eliminate noise in three aspects: ______, ______ and ______.

5. The resident opposite Xiao Ming's house is renovating his room, which affects his study and rest. In order to reduce the impact, Xiao Ming designed the following plan, the best of which is ()

A. Close the doors and windows tightly

B. Plug your ears with cotton

C. Open the doors and windows and plug your ears with cotton

D. Close the doors and windows tightly and plug your ears with cotton

Lectures in class

Knowledge point 1. Application of sound in life

(1) Sound can convey information

Rumbling thunder in the distance and dense clouds in the sky indicate that a heavy rain may be coming; railway workers use hammers to hit the rails, and loose bolts can be found from one of the characteristics of the sound - the tone; many organs in the human body are It is constantly moving, causing vibrations and sound. When an organ is diseased or abnormal, the sound will change. Doctors can use a stethoscope to understand the working status of the patient's heart and lungs. In ancient times, sailors sailing in the fog judged distances through the echo of horns. These are all examples of sound transmitting information.

(2) Sound can transmit energy

(3) Sound and music

The study of sound also promotes the development of music. Nowadays, the use of computer technology for digital synthesis of music has made it possible to realistically imitate various sounds, which better satisfies people's cultural and artistic enjoyment.

(4) Sound and architecture

Modern buildings such as auditoriums and concert halls have very high acoustic requirements. They use different sound-absorbing materials and set up reflective panels in different directions to make the sounds heard clearer and fuller. For example, the "Echo Wall" and "Three-tone Stone" in the Temple of Heaven in Beijing were built based on the principle of sound reflection.

[Exercise 1] The walls of the cinema are decorated with pits, commonly known as "swallow mud". The purpose is ()

A. weaken echo

B． Prevent sound from damaging walls

C. increase the frequency of sound

D． Enhance loudness

[Exercise 2] As shown in the picture below, the doctor is using a stethoscope to diagnose a patient. The stethoscope uses the principle of sound __________ (fill in "has energy" or "transmits information"); the sound from the patient is transmitted to the doctor's ear through a rubber tube. Ears, this can improve the __________ of the sound (fill in "pitch" or "loudness").

Knowledge point 2. Ultrasound and infrasound

Research has found that the frequency range of sound waves is very wide, but normal human ears can only hear sounds between 20 Hz and 20,000 Hz, and sounds below and above this frequency range cannot be heard by humans. Sounds above 20 000 Hz are usually called ultrasound, and sounds below 20 Hz are called infrasound. Ultrasound has many special uses.

(1) Detection using ultrasound

Ultrasound has strong penetrating ability and can propagate to long distances in a straight line. When it encounters an obstacle, part of the ultrasound is reflected back. According to the time and intensity of ultrasonic reflection, the location and range of obstacles can be determined. Therefore, ultrasound can be used to detect ocean depth, the location and size of fish schools, and the topography of the seabed, etc. Ultrasound can also be used to check whether there are defects inside metal products.

(2) Ultrasonic frequency is high and can cause severe vibration of the medium. Taking advantage of this feature, you can use ultrasonic cleaning equipment, washing dishes, washing clothes, etc.

(3) The application of ultrasound in medicine is developing rapidly. On the one hand, ultrasound can be used for human body examination, emitting beams of ultrasound to the body, and through the reflected signals, it can be seen whether there are lesions in the body, as well as the location and condition of the lesions, etc. This is the "B-ultrasound" often done in hospitals. This kind of examination does not require surgery and does not damage the body's tissues. It is safe and convenient. On the other hand, ultrasound can be used for treatment. Ultrasound can be emitted to the affected area to cause human cells to vibrate, heat, and accelerate metabolism to achieve the purpose of treatment. Ultrasonic waves can be used to break up stones in the body, such as kidney stones. After being crushed by ultrasonic waves, they can be automatically expelled from the body, saving patients from the pain of surgery.

Knowledge point 3. Control and reduce noise

(1)Noise and its sources:

① From a physical point of view, noise refers to the sound emitted when the sound-emitting body vibrates irregularly and disorderly.

② From the perspective of environmental protection, all sounds that hinder people's normal rest, study and work, as well as sounds that interfere with the sounds that people want to hear, are noises. When studying this section, you should start from the perspective of environmental protection, understand the harm of noise and ways to reduce noise, and improve your awareness of environmental protection. Noise from a physical perspective will not be discussed in this section. Because of this, in some cases, musical sound can also be annoying and become noise that pollutes the environment. For example, when we are doing homework at home, the neighbor's stereo is playing beautiful pop songs. If the sound is too loud, it will interfere with our study and it will be noise.

③Noise mainly comes from humans themselves and machines invented by humans.

(2)Noise level:

① Decibel (dB): People use decibel to divide the level of sound. It is a unit for measuring the intensity of sound. 0dB is the weakest sound that people can just hear - the lower limit of hearing.

②To protect hearing, the sound should be controlled not to exceed 90dB; to ensure work and study, the sound should be controlled not to exceed 70dB; to ensure rest and sleep, the sound should be controlled not to exceed 50dB.

1. (2013 Guangdong, 1, 3 points) Among the following statements about sound phenomena, which one is correct ( )

A. Everything that makes sound is vibrating

B． The human ear can hear sounds of various frequencies

C. Sound can travel in a vacuum

D． Sound cannot travel in water

2. (2014 Guangdong, 1, 3 points) Which of the following statements about sound is correct ( )

A. Sound is a type of electromagnetic wave

B． The higher the frequency of the sound, the louder it is

C. Sound is produced by the vibration of objects

D． The greater the amplitude of the sound, the higher the pitch

Test Point 2 Characteristics of Sound (High Frequency Test Point)

Test point analysis: This test point is a high-frequency test point in the Guangdong High School Entrance Examination, and it is also a test point that is difficult to master in this chapter. Knowledge to pay attention to in this test point: The three characteristics of sound are: pitch, loudness, and timbre, which describe sound from different angles Pitch refers to the level of the sound, which is determined by the vibration frequency. The frequency is shown as densely arranged on the waveform; loudness refers to the strength or size of the sound, which is determined by the amplitude and the distance from the sound source. The amplitude is shown as deviating from the balance on the waveform. The position is far; the timbre reflects the quality and characteristics of the sound. Different sound-emitting bodies have different materials and structures, and the timbre of the sound is also different.

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"Let Sound Serve Humanity" Sound and Environment PPT Courseware:

"Let Sound Serve Humanity" Sound and Environment PPT Courseware Teaching Objectives: 1. Understand the application of sound knowledge in music and architecture; 2. Know the sources of noise and methods and ways to control and reduce noise. 3. The application of sound in modern technology, training...

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Update Time: 2024-10-17

This template belongs to Physics courseware Guangdong and Shanghai version of eighth grade physics volume one industry PPT template

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