PTE Listening Practice Test 11

"Each autumn, millions of monarch butterflies undertake a remarkable multi-generational migration from as far north as Canada to overwintering sites in the mountain forests of central Mexico. What makes this migration particularly puzzling to scientists is that no single butterfly completes the entire round trip; the individuals that migrate south in autumn are several generations removed from those that return north the following spring. Researchers believe monarchs navigate using a combination of an internal sun compass and sensitivity to Earth's magnetic field, allowing them to maintain a consistent southward direction even on cloudy days. Upon arriving in Mexico, monarchs cluster together by the millions on specific fir trees, forming dense colonies that help conserve warmth during the cool mountain winter. The following spring, these same butterflies begin the journey north, but most die after laying eggs partway through the return trip, leaving their offspring to complete the remaining generations of the journey. This migration is increasingly threatened by deforestation at the Mexican overwintering sites and by the loss of milkweed plants across North America, since monarch caterpillars can feed on no other plant. Conservation efforts now focus on protecting the Mexican forest reserves and encouraging the planting of milkweed along the butterflies' migratory corridor."

মোনার্ক প্রজাপতি প্রতি শরতে কানাডা থেকে মেক্সিকো পর্যন্ত অভিবাসন করে — কিন্তু একটি প্রজাপতিই পুরো যাত্রা সম্পন্ন করে না, একাধিক প্রজন্ম মিলে করে। সূর্য কম্পাস ও চৌম্বক ক্ষেত্র ব্যবহার করে দিক নির্ণয় করে। বন উজাড় ও মিল্কউইড হ্রাস অভিবাসনকে হুমকিতে ফেলেছে।

"Active noise-cancelling headphones work by using tiny built-in microphones to detect incoming sound waves from the surrounding environment, then generating an inverse sound wave that cancels out much of that noise before it reaches the wearer's ear. This technology is particularly effective at cancelling low-frequency, constant sounds such as aeroplane engine hum or air conditioning, but considerably less effective against sudden, high-frequency sounds such as a dog barking or a door slamming, since the system requires a fraction of a second to detect and respond to a new sound. Some researchers have also raised questions about whether prolonged use of noise-cancelling technology in very quiet environments might affect a person's auditory processing over time, though robust long-term studies on this question remain limited. Despite these open questions, sales of noise-cancelling headphones have grown substantially, driven partly by demand from frequent air travellers and people working in noisy open-plan offices."

"Despite predictions that the internet would render physical libraries obsolete, public libraries in many countries have instead evolved and, in some cases, seen visitor numbers grow. Modern libraries increasingly function as community hubs, offering free internet access and computer literacy classes to residents who may not otherwise have reliable access to these resources at home. Libraries have also expanded well beyond books, lending items ranging from tools and musical instruments to museum passes, and hosting free events such as job-search workshops and children's reading programmes. Librarians report that during periods of economic hardship, demand for library services, particularly free internet access and job-search assistance, tends to increase rather than decrease, suggesting libraries serve an important social safety-net function beyond their traditional role as book-lending institutions."

"Developing artificial intelligence systems capable of accurately translating sign languages presents challenges quite different from those involved in translating between spoken languages. Sign languages are not simply gestural versions of spoken language grammar; they have their own independent grammatical structures, and meaning is conveyed not only through hand shapes and movements but also through facial expressions, body posture, and the specific space around the signer's body. Current computer vision systems often struggle to reliably track and interpret this combination of simultaneous visual information in real time, particularly facial expressions that carry essential grammatical information, such as raised eyebrows indicating a question. Additionally, most existing sign language datasets used to train these systems are limited in size compared to the vast text corpora available for spoken language translation, and sign languages vary significantly by country and region."

"Natural diamonds form under extreme heat and pressure roughly one hundred and fifty kilometres beneath the Earth's surface, and are brought closer to the surface only through rare, deep volcanic eruptions known as kimberlite eruptions."