Please explain this question to me using the physical acoustic phenomena of the second year of junio

This is because of the frequency problem, because the car will have a compression effect on the sound waves during driving, then the wavelength of the sound wave will become shorter and the frequency will increase, at this time the sound you hear is sharper than the original, and when the car drives past you, the sound wave has changed back to the original wavelength and frequency, then at this time you hear a normal sound, and this time is the reason why you feel dull.

This is a classic Doppler effect. See.

Because the car will have a compression effect on the sound waves during driving, then the wavelength of the sound waves will become shorter and the frequency will increase, at this time the sound you hear is sharper than the original, and when the car drives past you, the sound waves of the sound have changed back to the original wavelength and frequency, then at this time you hear a normal sound, and this time is the reason why you feel dull.

This requires high school physics knowledge, and the Doppler effect in mechanical waves, where what you call a sound becoming "sharp" or "dull" is caused by a change in frequency rather than a change in pitch.

It seems to be called the Doppler effect.........

It is a phenomenon in which the frequency of sound changes due to the movement of the sound source.

The train is moving forward, and so is the sound wave.

Tone is related to frequency.

1.(1) Tone, loudness, and timbre all describe the characteristics of sound.

Tone: The level of sound is related to the speed of the vibration of the object, the faster the object vibrates, the higher the pitch emitted; The slower the vibration, the lower the pitch; Frequency determines tone.

Loudness: In physics, the strength of a sound is called loudness. Loudness is what we usually call the volume of sound.

Loudness is related to the amplitude of the emitter and the distance from the emitter. At the same distance, the greater the amplitude, the louder it is. The main ways to increase loudness are:

Reduce the divergence of sound.

Timbre: In physics, the sound produced by different objects has different characteristics called musical quality. It is determined by the object itself, that is:

Timbre is related to the material and structure of the emitter. People are able to distinguish different instruments or distinguish different people based on their timbre.

2) Adjectives:

Tones: High, sharp, harsh, 、......

Loudness: Loud, deafening、......

Timbre: beautiful, pleasant, beautiful 、......

2.Sound & Information: Sound can transmit information. (For example: hearing thunder, it is very likely to rain, B ultrasound to check for organ lesions, knock on the porcelain bowl, to determine whether there are cracks, etc.).

Sound & Energy: Sound energy transmits energy. (e.g. ultrasonic cleaning of precision instruments, ultrasonic stone crushing).

1. I think that the tone is the degree that reflects the sharpness and richness of the voice, and the loudness reflects the size, which can be described with words such as whispering, and the timbre is that everyone's voice sounds different, that is, the timbre is different.

2. Transmitting energy is like it has a certain strength, and transmitting information means that we can hear something from the sound, just like buying a watermelon when you knock it to determine whether the watermelon is ripe.

When a student was picking watermelons, he flicked them with his fingers a few times, and the sound was crisp and dull, and he judged the raw and ripe watermelons based on this. He applied his knowledge of physics (different timbres) to study the frequency relationship between the pitch of sound and the vibration of the emitter using a tuning fork and an oscilloscope. In this experiment, he conducted two experiments, the first time striking a tuning fork with a frequency of 512 Hz, and the second time striking a tuning fork with a frequency of 256 Hz with the same force, and the result was that the first sound was heard to be higher pitch.

The conclusion from this is that the faster the emitter vibrates, the higher the frequency, and the higher the pitch (optionally "high" or "low").

A student uses an oscilloscope, a hacksaw blade, and a vice to study the loudness of sound. As shown in the picture on the left below, he clamped the lower end of the hacksaw blade to the vice, and the upper end was pulled by hand to make the hacksaw blade vibrate and make a sound. In the experiment, he carried out two experiments, the first saw blade made a sound sound, the second saw blade made a light sound, and he observed that the amplitude of the waveform displayed on the oscilloscope is shown in the following figures (a) and (b) on the right, respectively, then he came to the experimental conclusion:

The greater the amplitude, the louder the sound, look.

Experiment Answers:

1.Tone. 2.Frequency high.