<?php

$ar = array("/Volumes/SAMPLES/  VOCALS/", 
    "/Volumes/SAMPLES/  VOCALS/  AFRICA/",
    "/Volumes/SAMPLES/  VOCALS/ AcmeInc Club Vocals/",
    "/Volumes/SAMPLES/  VOCALS/ AtomicInc Dance Vocals/",
    "/Volumes/SAMPLES/  VOCALS/  AFRICA/ AfroInc Zulu Vocals/",
    "/Volumes/SAMPLES/  VOCALS/  AFRICA/ SampleInc Warriors/",
    "/Volumes/SAMPLES/  VOCALS/  AFRICA/ SampleInc Warriors/SampleInc_Warriors_Ululation/",
    "/Volumes/SAMPLES/  VOCALS/  AFRICA/ SampleInc Warriors/SampleInc_Warriors_Drums/",
    "/Volumes/SAMPLES/  VOCALS/  AFRICA/ AfroInc Zulu Vocals/ Folder1/"
	);
$n = preg_grep('~/(?:  +[^/\s]+)*/ [^/\s]+(?: +[^/\s]+)*/$~', $ar);
print_r($n);