```html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">

<title>Listening Discrimination – /θ/ and /ð/</title>
<meta name="description" content="Listening discrimination practice contrasting /θ/ and /ð/ in British English.">
<meta name="keywords" content="British English, pronunciation, phonology, phonemes, listening discrimination, minimal pairs, language learning, EFL, ESL, ELT">

<style>
@page {
    size: A4;
    margin: 20mm;
}

* {
    box-sizing: border-box;
}

html, body {
    margin: 0;
    padding: 0;
}

body {
    background: #e5e5e5;
    color: #222;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 17px;
    line-height: 1.6;
}

.page {
    width: 210mm;
    min-height: 297mm;
    margin: 15mm auto;
    padding: 20mm 25mm;
    background: white;
    box-shadow: 0 0 10px rgba(0,0,0,.22);
}

.screen-nav {
    margin: 0 0 20px;
    padding: 8px 0;
    text-align: center;
    font-size: 14px;
    border-bottom: 1px solid #ddd;
}

.screen-nav a {
    color: #245a8d;
    text-decoration: none;
    margin: 0 6px;
}

.screen-nav a:hover,
.screen-nav a:focus {
    text-decoration: underline;
}

h1 {
    margin: 0 0 18px;
    text-align: center;
    font-size: 21px;
    line-height: 1.3;
    font-weight: 600;
}

.introduction {
    margin: 0 auto 24px;
    text-align: center;
}

.phoneme {
    font-family: "Lucida Sans Unicode", "Arial Unicode MS", Arial, sans-serif;
}

.instructions {
    max-width: 650px;
    margin: 0 auto 28px;
    text-align: center;
}

.exercise {
    max-width: 620px;
    margin: 0 auto;
    text-align: center;
}

.question-number {
    margin-bottom: 18px;
    font-size: 18px;
    font-weight: bold;
}

.listen-area {
    margin: 20px 0 28px;
}

.listen-button {
    padding: 10px 24px;
    border: 1px solid #999;
    border-radius: 4px;
    background: #f3f3f3;
    color: #222;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 17px;
    cursor: pointer;
}

.listen-button:hover,
.listen-button:focus {
    background: #e6e6e6;
}

.question {
    margin-bottom: 18px;
    font-size: 18px;
}

.answers {
    display: flex;
    justify-content: center;
    gap: 30px;
    margin: 20px auto;
}

.answer-button {
    width: 180px;
    min-height: 52px;
    padding: 10px 15px;
    border: 1px solid #999;
    border-radius: 4px;
    background: white;
    color: #222;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 18px;
    cursor: pointer;
}

.answer-button:hover,
.answer-button:focus {
    background: #f1f1f1;
}

.answer-button.correct {
    background: #e4f2e4;
    border-color: #4d8b4d;
}

.answer-button.incorrect {
    background: #f7e3e3;
    border-color: #a44;
}

.feedback {
    min-height: 58px;
    margin: 20px auto;
    max-width: 560px;
    font-size: 17px;
}

.feedback strong {
    display: block;
    margin-bottom: 4px;
}

.next-button {
    display: none;
    padding: 9px 20px;
    border: 1px solid #777;
    border-radius: 4px;
    background: #eee;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 16px;
    cursor: pointer;
}

.next-button:hover,
.next-button:focus {
    background: #ddd;
}

.score {
    display: none;
    margin: 30px auto;
    padding: 18px;
    max-width: 500px;
    border-top: 1px solid #ccc;
    text-align: center;
    font-size: 18px;
}

.restart-button {
    padding: 8px 18px;
    border: 1px solid #777;
    border-radius: 4px;
    background: #eee;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 15px;
    cursor: pointer;
}

.footer {
    margin-top: 35px;
    text-align: center;
    font-size: 13px;
}
@media (max-width: 800px) {
    body {
        background: white;
    }

    .page {
        width: 94%;
        min-height: auto;
        margin: 20px auto;
        padding: 24px 28px;
        box-shadow: none;
    }

    .answers {
        gap: 15px;
    }

    .answer-button {
        width: 45%;
    }
}

@media print {
    body {
        background: white;
        font-size: 12pt;
    }

    .page {
        width: 100%;
        min-height: 0;
        margin: 0;
        padding: 0;
        box-shadow: none;
    }

    .screen-nav,
    .listen-area,
    .next-button,
    .restart-button {
        display: none !important;
    }

    h1 {
        font-size: 18pt;
    }

    .footer {
        font-size: 9pt;
    }
}

.next-exercise {
    margin: 28px auto 0;
    padding-top: 18px;
    border-top: 1px solid #ddd;
    text-align: center;
    font-size: 15px;
}

.next-exercise a {
    color: #245a8d;
    text-decoration: none;
}

.next-exercise a:hover,
.next-exercise a:focus {
    text-decoration: underline;
}

@media print {
    .next-exercise {
        display: none;
    }
}
</style>
</head>

<body>

<div class="page">

    <div class="screen-nav">
    <a href="minimal-exercises.html">Minimal Pairs: Listening exercises</a> |<a href="minimal.html">Minimal Pairs</a> |
        <a href="phono.html">L1 pronunciation problems</a> |
        <a href="index.html">Home</a>
    </div>

    <h1>
        Listening Discrimination –
        <span class="phoneme">/θ/</span> and
        <span class="phoneme">/ð/</span>
    </h1>

    <p class="introduction">
        <span class="phoneme">/θ/</span> as in <strong>"thigh"</strong>
        &nbsp; · &nbsp;
        <span class="phoneme">/ð/</span> as in <strong>"thy"</strong>
    </p>

    <p class="instructions">
        Listen to the word. Then choose the word you hear.
        You can listen again if necessary.
    </p>

    <div class="exercise">

        <div class="question-number" id="questionNumber">
            Question 1 of 10
        </div>

        <div class="listen-area">
            <button type="button"
                    class="listen-button"
                    onclick="listen()">
                🔊 Listen
            </button>
        </div>

        <div class="question">
            Which word did you hear?
        </div>

        <div class="answers">

            <button type="button"
                    class="answer-button"
                    id="answerA"
                    onclick="checkAnswer(0)">
            </button>

            <button type="button"
                    class="answer-button"
                    id="answerB"
                    onclick="checkAnswer(1)">
            </button>

        </div>

        <div class="feedback" id="feedback"></div>

        <button type="button"
                class="next-button"
                id="nextButton"
                onclick="nextQuestion()">
            Next Question
        </button>

    </div>

    <div class="score" id="score"></div>

    <div class="footer">
        Listening discrimination practice – British English consonant contrast
    </div>
<div class="next-exercise">
    <a href="minimal2931i.html">
        Next exercise: Minimal Pairs Listening Discrimination – &quot;thin&quot; and &quot;sin&quot; →
    </a>
</div>

</div>

<script>

const pairs = [
    ["thigh", "thy"],
    ["mouth", "mouth"],
    ["teeth", "teethe"],
    ["wreath", "wreathe"],
    ["ether", "either"],
    ["cloths", "clothes"],
    ["cloth", "clothe"],
    ["bath", "bathe"],
    ["breath", "breathe"],
    ["sooth", "soothe"]
];

let questions = [];
let currentQuestion = 0;
let score = 0;
let answered = false;


/* Shuffle the questions. */
function shuffle(array) {
    const copy = [...array];

    for (let i = copy.length - 1; i > 0; i--) {
        const j = Math.floor(Math.random() * (i + 1));
        [copy[i], copy[j]] = [copy[j], copy[i]];
    }

    return copy;
}


/*
   Prepare the questions.

   The correct answer is randomly placed on
   the left or right.
*/
function prepareQuestions() {

    questions = shuffle(pairs).map(pair => {

        const correct = Math.floor(Math.random() * 2);

        return {
            pair: pair,
            correct: correct,
            word: pair[correct]
        };
    });
}


/* Display one question. */
function showQuestion() {

    const q = questions[currentQuestion];

    document.getElementById("questionNumber").textContent =
        "Question " + (currentQuestion + 1) +
        " of " + questions.length;

    document.getElementById("answerA").textContent =
        q.pair[0];

    document.getElementById("answerB").textContent =
        q.pair[1];

    document.getElementById("answerA").className =
        "answer-button";

    document.getElementById("answerB").className =
        "answer-button";

    document.getElementById("feedback").innerHTML = "";

    document.getElementById("nextButton").style.display =
        "none";

    answered = false;
}


/*
   Speak the word.

   A single Listen button is used for each question.
   Safari will use an available British English voice
   when one is available.
*/
function listen() {

    const q = questions[currentQuestion];

    if (!("speechSynthesis" in window)) {
        document.getElementById("feedback").innerHTML =
            "<strong>Speech is not available.</strong>" +
            " Your browser does not support speech synthesis.";
        return;
    }

    window.speechSynthesis.cancel();

    const utterance =
        new SpeechSynthesisUtterance(q.word);

    utterance.lang = "en-GB";
    utterance.rate = 0.75;
    utterance.pitch = 1;

    const voices =
        window.speechSynthesis.getVoices();

    const britishVoice = voices.find(voice =>
        voice.lang &&
        voice.lang.toLowerCase().startsWith("en-gb")
    );

    if (britishVoice) {
        utterance.voice = britishVoice;
    }

    window.speechSynthesis.speak(utterance);
}


/* Give immediate feedback. */
function checkAnswer(choice) {

    if (answered) {
        return;
    }

    answered = true;

    const q = questions[currentQuestion];

    const chosenButton =
        choice === 0
            ? document.getElementById("answerA")
            : document.getElementById("answerB");

    const correctButton =
        q.correct === 0
            ? document.getElementById("answerA")
            : document.getElementById("answerB");

    if (choice === q.correct) {

        score++;

        chosenButton.classList.add("correct");

        document.getElementById("feedback").innerHTML =
            "<strong>Correct!</strong>" +
            " You heard <strong>" +
            q.word +
            "</strong>.";

    } else {

        chosenButton.classList.add("incorrect");
        correctButton.classList.add("correct");

        document.getElementById("feedback").innerHTML =
            "<strong>Not quite.</strong>" +
            " The word was <strong>" +
            q.word +
            "</strong>.";
    }

    if (currentQuestion < questions.length - 1) {

        document.getElementById("nextButton").style.display =
            "inline-block";

    } else {

        showFinalScore();
    }
}


/* Go to the next question. */
function nextQuestion() {

    currentQuestion++;

    showQuestion();

    window.scrollTo({
        top: 0,
        behavior: "smooth"
    });
}


/* Show final score. */
function showFinalScore() {

    const scoreBox =
        document.getElementById("score");

    scoreBox.innerHTML =
        "<strong>Exercise complete</strong><br><br>" +
        "Your score: <strong>" +
        score +
        " out of " +
        questions.length +
        "</strong><br><br>" +
        '<button type="button" class="restart-button" ' +
        'onclick="restartExercise()">' +
        "Try Again" +
        "</button>";

    scoreBox.style.display = "block";
}


/* Restart with a new random order. */
function restartExercise() {

    currentQuestion = 0;
    score = 0;

    document.getElementById("score").style.display =
        "none";

    prepareQuestions();
    showQuestion();

    window.scrollTo({
        top: 0,
        behavior: "smooth"
    });
}


/*
   Safari loads speech voices asynchronously.
*/
if ("speechSynthesis" in window) {

    window.speechSynthesis.onvoiceschanged =
        function() {
            window.speechSynthesis.getVoices();
        };
}


/* Start the exercise. */
prepareQuestions();
showQuestion();

</script>

</body>
</html>
```