ABX.sh

#!/usr/bin/bash

PLAYER="play -q"
# `play` is from sox package; `man soxformat` for supported formats

if [[ $# <3 ]]; then
    echo 'ABX test for audio files.'
    echo
    echo "Usage: $0  <n> <wave_A> <wave_B>"
    echo '  n          - number of tests performed (n >= 10 is recommended)'
    echo '  wave_{A,B} - audio files supported by PLAYER'
    echo '  Make your waves shorter.'
    echo
    echo 'Correct results required for a 95% confidence level:'
    echo 'n  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25'
    echo 'CR  9   9  10  10  11  12  12  13  13  14  15  15  16  16  17  18'
    echo 'In general, CR must be greater than n/2+sqrt(n).'
    echo
    echo "PLAYER = \"${PLAYER}\""
    echo
    exit 1
fi

n=$1
wave_A="$2"
wave_B="$3"
waves_AB=("$wave_A" "$wave_B")
AB=("A" "B")

echo "In each test, \"${wave_A}\" then \"${wave_B}\" will be played."
echo "Then you'll hear randomly selected one — \"X\"."
echo "After the third sample you'll be asked for what file been played."
echo 'Answer only "A" or "B" and then press Enter.'

correct_answers=0

for i in $(seq $n); do
    echo
    echo "Test #${i} of ${n}:"

    echo -ne "\tA | Press Enter when ready. "; read
    $PLAYER "$wave_A"

    echo -ne "\tB | Press Enter when ready. "; read
    $PLAYER "$wave_B"

    random=$(( $RANDOM % 2 ))
    wave_X=${waves_AB[random]}
    X=${AB[random]}

    echo -ne "\tX | Press Enter when ready. "; read
    $PLAYER "$wave_X"

    while true; do
        echo -ne '\tWas that A or B? : '
        read answer
        if [[ $answer =~ ^[aAbB] ]]; then
            break
        fi
    done

    if [[ ($answer =~ ^[aA] && $X == 'A') || \
          ($answer =~ ^[bB] && $X == 'B') ]]; then
        correct_answers=$(( $correct_answers + 1 ))
    fi
done

echo
echo "Congratulations! You've done all the ${n} tests!"
echo "Your result is ${correct_answers}/${n}."
echo "Bye."