Count consonants in a word randomly found in an array

I want to take a random string of the array and should count the consonants of the random string. Problem is it did not count the letters from array_rand().

Here is what I get at this point:

$woerter = [
    "Maus",
    "Automobil",
    "Schifffahrt",
    "Hund",
    "Katze",
    "Ziege",
    "Stanniolpapier",
    "Elefant",
    "Isopropylalkohol",
    "Schwimmbad"
];

$random = array_rand($woerter);

$konsonanten = ["b","c","d","f","g","h","j","k","l","m","n","p","q","r","s","t","u","v","w","x","y","z",
            "B","C","D","F","G","H","J","K","L","M","N","P","Q","R","S","T","U","V","W","X","Y","Z"];
$zaehler = 0;
if (in_array($woerter[$random], $konsonanten)) {
    $zaehler++;
}

echo "Das Wort \"$woerter[$random]\" enthält $zaehler Zeichen, die keine Vokale sind.";

You're testing whether the whole word is in the array of consonants, not counting each character. You need to loop over the characters.

$word = $woerter[$random];
for ($i = 0; $i < strlen($word); $i++) {
    if (in_array($word[$i], $konsonanten)) {
        $zaehler++;
    }
}