When a length of string (or a column of air) is made to vibrate it produces a pitch.
Cabdinaasir ayaa tilmaamay in qaraxaasi uu ka danbayey wiil yar oo Fayuus ku tuuray gaari waddada marayey kadibna Fayuuskaasu uu ku qarxay gudaha gaariga, afar qof ayuu sheegy gudoomiye ku xigeenku inay qaraxaasi waxku noqdeen balse hadda ay dhamaantood caafimaad qabaan.