Đề ôn thi Đề thi vào lớp 10 Trường THPT Chuyên KHXH môn Tiếng Anh - Mã đề KHXH-169

Have you ever noticed the 'L' and 'R' letters on your headphones? These symbols are not just for decoration; they indicate the left and right audio channels. Each channel plays a slightly different audio track, which is a key feature of stereo sound. The purpose is to send (35) __________ audio information to each of your ears, just like you hear sounds in the real world from different directions.

This system is called stereophonic sound, or 'stereo' for short. By playing different sounds in each ear, audio engineers can create a sense of direction and space. So that your brain (36) __________ process these differences, the soundscape feels wider and more three-dimensional. A stereo recording is almost always (37) __________ immersive than a mono recording, where the exact same sound is sent to both ears.

Our brains are naturally skilled at identifying where sounds come from. (38) __________ is because our two ears hear sounds at slightly different times and volumes depending on their source. Stereo technology uses this principle to (39) __________ an experience that feels natural. For example, a sound that is louder in the right channel will seem to come from your right side.

This technology greatly improves the listening experience. When you listen to music, you might hear the guitar primarily in your left ear and the piano in your right, making the mix feel more spacious and (40) __________. In movies, it allows for sound effects to move from one side to the other, following the action on screen. (41) __________ does this make media more engaging, but it is also essential for applications like gaming, where knowing the direction of a sound is crucial.

(42) __________, the 'L' and 'R' on your headphones are fundamental to creating a rich and convincing audio world. They enable stereo sound, which works with your brain's natural abilities to simulate a realistic, three-dimensional soundscape. The next time you put on your headphones, pay attention to the different sounds in each ear and appreciate the clever technology at work.

In the bustling cities of the 21st century, we are surrounded by a constant symphony of sounds: the roar of traffic, the buzz of construction, and the chatter of crowds. While we often dismiss this as the normal soundtrack of urban life, scientists and health experts are increasingly warning us about an invisible threat: noise pollution. Unlike other forms of pollution, you can't see or smell it, but its effects on our well-being are significant. In Vietnamese cities like Hanoi and Ho Chi Minh City, this issue is particularly acute, with the incessant honking of vehicle horns and blaring promotional loudspeakers forming a familiar, yet stressful, part of daily existence.

The health consequences of prolonged exposure to high levels of noise are well-documented and far-reaching. The most immediate effect is stress. The body interprets loud, unpredictable noise as a danger signal, triggering a 'fight or flight' response that releases stress hormones like cortisol. Over time, this chronic stress can lead to serious cardiovascular problems, including high blood pressure and an increased risk of heart disease. Furthermore, noise pollution is a major disruptor of sleep. Even if you don't fully wake up, noise at night can prevent you from reaching the deep, restorative stages of sleep, leaving you tired and irritable the next day. These effects are detrimental to both physical and mental health.

Beyond general health, noise pollution has a profound impact on cognitive functions, especially those essential for learning. Numerous studies have shown that students in noisier environments struggle more with concentration, memory retention, and reading comprehension. The constant background noise makes it difficult for the brain to filter out irrelevant information and focus on academic tasks. These effects are particularly concerning for young people, as consistent exposure to noise can hinder their academic development and long-term potential. Essentially, a noisy journey to school or a loud neighborhood can create an invisible barrier to effective learning.

Recognizing this problem, authorities in Vietnam have taken some steps to mitigate the issue. For instance, Decree 100/2019/ND-CP imposes penalties on drivers who misuse their horns, especially in urban areas or during night hours. However, the enforcement of such regulations can be challenging, and the deeply ingrained culture of using horns for communication persists. Similarly, while rules exist to control the volume of promotional loudspeakers, they are often ignored, contributing to the overall sonic chaos of the city. These specific local factors compound the universal challenges of managing urban noise.

Tackling noise pollution requires a multi-faceted approach. Better urban planning that separates residential areas from major noise sources, the promotion of quieter electric vehicles, and stricter enforcement of existing laws are all crucial government-led strategies. On an individual level, people can take small steps such as using noise-canceling headphones or advocating for quieter communities. Addressing the invisible pollution of noise is not just about seeking peace and quiet; it's a vital public health imperative for creating healthier, more productive cities for future generations.