The soundex() function in PHP 8.4 and 8.5 works exactly the same as in previous versions. It calculates the Soundex key of a string—a four-character code that represents how an English word sounds, rather than how it is spelled. This is useful for building "sounds like" searches, like matching "Smith" with "Smyth" .
Example
Here is how it works with a simple word:
<?php
$str = "Hello";
echo soundex($str); // Output: H400
?>
The function returns a string starting with the first letter, followed by three digits representing the consonant sounds. Vowels and letters like h, w, y are ignored.