シャドーイング練習: Every Mobile Network Explained in 8 Minutes - 動画で英語スピーキングを学ぶ
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80 文
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1
1G.
2
1G, or first generation, came out in the early 1980s, and this was the first time people could call someone wirelessly.
3
It was created because back then, phones were still connected to cables, meaning you could only make calls from certain places like homes or offices, which made phone calls inconvenient.
4
That's why the 1G mobile network was created, allowing people to make phone calls wirelessly.
5
And all of this was possible because 1G used analog transmission, which converted your voice into radio signals and sent the signal through the air.
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However, even though 1G phones were portable, they were still thick and heavy compared to the phones we use today.
7
And unlike phones with modern mobile networks that already support internet access, navigation, and online gaming, 1G was designed literally only for voice calls.
8
It couldn't even send text messages, which is why 1G phones only had a small screen mainly for showing numbers during calls.
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And despite being specifically made for voice calls, the 1G network had many problems.
10
For example, during phone calls, voices could sound unclear because analog radio signals often picked up noise and echoes.
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On top of that, the 1G network has no encryption feature yet.
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So if someone had a radio scanner and scanned your phone's radio frequency, they could listen to your phone call without you knowing.
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Another problem was that you could only talk for around 20 to 30 minutes before the phone died.
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That's because the analog technology in 1G had to continuously convert your voice into radio signals and transmit them.
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And this used a lot of energy.
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So in the end, since 1G and its phones had too many problems, the 2G network was created later to fix those issues.
17
2G.
18
2G came out in the early 1990s, and this is where mobile networks switched from analog to digital signals.
19
So instead of sending your voice as radio waves like in 1G, which made calls sound distorted and easy to eavesdrop on,
20
2G converted your voice into digital data that sounded much clearer and more secure.
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And since 2G used digital signals, phones could finally send SMS text messages.
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And this feature was great because sometimes people just wanted to say something briefly without having to make a call.
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Other than that, 2G also introduced mobile data.
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The earliest version was called GSM, but the data speed was only around 14.4 kilobits per second, which was extremely slow and not enough for real internet browsing yet.
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Later on, GSM was upgraded to GPRS, or also known as 2.5G, which increased speeds to around 80 kilobits per second.
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After that, it was upgraded again to Edge, or 2.75G, and this time the speed could reach up to 200 kilobits per second.
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However, even with these upgrades, 2G was still too slow for browsing the internet.
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And not only that, it also had a very high latency, so when you click something, the response felt delayed and unresponsive.
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And to make it worse, websites back then had to be typed manually, letter by letter.
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So in the end, as more and more people started using the internet, the 2G network was no longer capable, which is why it was replaced by 3G later.
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3G 3G came out in the early 2000s, and this is the first mobile network that was made for internet use.
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So unlike 2G that was mainly only for calling and texting, 3G was already capable of handling things like email, browsing websites, and even social media.
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This is possible because the data speed of 3G could reach around 384 kilobits per second, which is much faster than 2G.
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Later on, the regular 3G was upgraded to HSPA and HSPA+, or 3.5G and 3.75G.
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With these upgrades, 3G speeds could reach around 5 to 10 megabits per second, which was enough for things like watching early YouTube videos and making basic video calls.
36
However, even with these improvements, 3G speeds were often unstable, especially when many people were online at the same time.
37
As a result, people often had to watch online videos or view images in lower resolutions.
38
And since apps and online features became more and more demanding, the 3G network and its phones couldn't handle them anymore.
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That's why 4G was created later.
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4G.
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4G, which also known as LTE, came out around 2010.
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And this is the network generation that created the smartphone era.
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So unlike 3G that could connect to the internet but was often unstable, 4G was built with the internet as the main focus.
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This is why 4G has much higher speeds,
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typically around 10 to 100 megabits per second and later upgrades like 4G plus could reach up to 300 megabits per second.
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With this people could stream higher resolution videos, download and upload large files, and even play online games smoothly.
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Also, if you take a look at 4G phone designs compared to the previous generation, you'll notice that most 4G phones use large touchscreens instead of many physical buttons.
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This happened because the higher speeds of 4G made phones capable of handling heavier
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and more complex apps like map navigation or video conferencing.
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And since these complex apps required scrolling, gesture controls and zooming, touchscreens became the natural interface during the 4G era.
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And not just speed, 4G is also more stable than 3G.
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This is because 4G networks were designed to serve many users at once more efficiently, so when lots of people are online at the same time,
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the connection doesn't get congested as easily as 3G.
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But of course, in very crowded places like stadiums or busy city areas, 4G can still slow down and become overloaded.
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And this congestion is becoming even more common as 4G smartphone users keep increasing every year, which is why 5G was created later.
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5G.
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5G came out in 2020, and this network is commonly used in mid-range to high-end smartphones today.
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Its speed can reach hundreds of megabits per second and even go beyond gigabit levels.
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And not only that, in a very crowded area where many people are online at the same time, 4G speeds can drop significantly, while 5G remains more stable.
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Also, 5G can deliver data with very low latency, usually around 15 to 30 milliseconds in real-world conditions.
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This is especially useful when you need an instant response, such as when playing competitive online games or using Google Maps with constant position updates.
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Also, during a disaster or when someone is lost, rescue teams can use a 5G connection to control a drone and view its live camera feed with almost no delay.
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In comparison, 4G latency can sometimes spike randomly, which makes things feel laggy and less responsive.
64
However, despite all these improvements, 5G coverage is still not as wide as older networks like 4G or 3G, and that's normal.
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Since 5G is relatively new, its infrastructure is still expanding.
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This means that in more remote or rural areas, you often won't get a 5G signal, even if your phone supports 5G, so your device will fall back to 4G or 3G instead.
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But even if you don't have 5G, 4G is enough for everyday tasks anyway, especially for casual users who watch videos or browse social media,
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since those activities don't require extreme speeds.
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6G 6G is the next generation after 5G, and unlike previous generations, it does not exist as a consumer mobile network yet.
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Instead, 6G currently exists at the research and infrastructure level, such as in satellites and laboratory networks.
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So right now, the main users of 6G are just research teams, large tech companies, and governments.
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In theory, 6G speeds could reach hundreds of gigabits per second, and in laboratory conditions, even up to 1 terabit per second.
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Also, it is said that 6G will be using an AI-integrated network system that can automatically optimize connections, predict demands, and manage traffic for many users.
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Because of this, 6G usage is not really about everyday phone apps anymore, but more about large-scale systems like scientific research and advanced automation.
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And based on how mobile networks evolve roughly every 10 years, 6G is expected to reach consumer devices around 2030.
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However, I gotta say that having 6G on your phone isn't really important anyway.
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Because today, even 5G is already very fast and offers low latency.
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And for most people, 4G is still more than enough for casual tasks like social media, messaging, or music streaming.
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Even for heavier activities like video calls or watching long videos on YouTube, most people will simply switch to Wi-Fi anyway.
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Oh by the way, I made some other cool videos too, so don't forget to watch them later, okay?
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このレッスンの語彙とスピーキングのポイント
このB2レベルのスピーキングレッスンは、動画「Every Mobile Network Explained in 8 Minutes」を教材にしています。 繰り返し出てくる語は次のとおりです：network, speed, online, signal, mobile。 この動画には、シャドーイング用の文が80文、単語が1446語あります。 音声の長さは8:13です。 話す速さは1分あたり約176語で、日常会話に近い自然なペースです。 英語の頻出3,000語に含まれる単語は80%だけなので、語彙は難しめです。
この動画の重要語彙
動画の中で特に難しい単語15語を、発音と意味つきで紹介します。
| 単語 | 発音 | 意味 |
|---|---|---|
| kilobit 名詞 | キロビット | |
| latency 名詞 | /ˈleɪ.tən.si/ | 潜在, 秘匿 |
| megabit 名詞 | /ˈmɛɡəbɪt/ | メガビット |
| browse 動詞 | /bɹaʊz/ | 閲覧する |
| analog 形容詞 | /ˈænəlɔɡ/ | アナログ |
| smartphone 名詞 | /ˈsmɑɹtfoʊn/ | スマートフォン, スマートホン |
| gigabit 名詞 | /ˈɡɪɡəbɪt/ | ギガビット |
| litter 名詞 | /ˈlɪt.ɚ/ | ごみ |
| unstable 形容詞 | /ʌnˈsteɪ.bəl/ | 不安定 |
| navigation 名詞 | /nævɪˈɡeɪʃən/ | ナビゲーション, 航法 |
| distort 動詞 | /dɪsˈtɔːt/ | 歪める, 曲げる |
| eavesdrop 動詞 | /ˈivzˌdɹɑp/ | 立ち聞きする |
| inconvenient 形容詞 | /ˌɪn.kənˈviːni.ənt/ | 面倒な, 不便な |
| millisecond 名詞 | /ˈmɪlɪˌsɛkənd/ | ミリ秒, ミリセカント |
| terabit 名詞 | テラビット |
動画に出てくる句動詞
| 単語 | 発音 | 意味 |
|---|---|---|
| come out 動詞 | /ˌkʌm ˈaʊt/ | 出る |
| pick up 動詞 | 拾う, 拾い上げる | |
| slow down 動詞 | 遅らせる |
この動画の文法
話し手がよく使っている文型を、動画の実際の表現とともに紹介します。
| 文型 | 動画での表現 |
|---|---|
| 受動態 be + 過去分詞 — 誰がするかより、何が起きるかに焦点を当てる | was created · was designed · was called |
| 関係詞節 who / which + 節 — 人や物について情報を加える | messages, which is · second, which was · capable, which is |
注意したい発音
話し手はdon't, couldn't, doesn'tなど、短縮形や弱形を10回使っています。聞こえたとおりの短い形で発音しましょう。
- 「sh」と「zh」の音: navigation /nævɪˈɡeɪʃən/, encryption /ɪnˈkɹɪpʃən/, automation /ˌɔ.təˈmeɪ.ʃən/
- 長い単語（アクセントの位置に注意）: navigation /nævɪˈɡeɪʃən/, inconvenient /ˌɪn.kənˈviːni.ənt/, millisecond /ˈmɪlɪˌsɛkənd/, manually /ˈmænj(u)əliː/, automation /ˌɔ.təˈmeɪ.ʃən/
日本語話者が苦手な音：
- /r/ と /l/ の区別 — /l/ は舌先を歯茎につけ、/r/ はどこにもつけない: scroll /skɹoʊl/, randomly /ˈɹændm̩li/, portable /ˈpɔɹtəbəl/
- /v/ — /b/ にならないように、上の歯を下唇に当てる: convert /kənˈvɝt/, navigation /nævɪˈɡeɪʃən/, eavesdrop /ˈivzˌdɹɑp/, inconvenient /ˌɪn.kənˈviːni.ənt/, overload /ˌəʊvəˈləʊd/
- /f/ — 「フ」ではなく、上の歯と下唇で出す: smartphone /ˈsmɑɹtfoʊn/, interface /ˈɪn(t)ɚˌfeɪs/
この動画での練習方法
- まず声を出さずに動画を最後まで聞き、知らない単語をメモします。
- まず0.75倍速で一文ずつシャドーイングし、慣れてきたら通常の速度に戻します。
- 自分の声を録音して元の音声と比べます。kilobit, latency, megabitなどの単語に特に注意しましょう。
シャドーイングとは？英語上達に効果的な理由
シャドーイング（Shadowing）は、もともとプロの通訳者養成プログラムで開発された言語学習法で、多言語習得者として知られるDr. Alexander Arguelles によって広く普及されました。方法はシンプルですが非常に効果的：ネイティブスピーカーの英語を聞きながら、1〜2秒の遅延で声に出してすぐに繰り返す——まるで「影（shadow）」のように話者を追いかけます。文法ドリルや受動的なリスニングと異なり、シャドーイングは脳と口の筋肉が同時にリアルタイムで英語を処理・再現することを強制します。研究により、発音精度、抑揚、リズム、連音、リスニング力、そして会話の流暢さが大幅に向上することが確認されています。IELTSスピーキング対策や自然な英語コミュニケーションを目指す方に特におすすめです。