Different types of fans have different acoustic signatures, which is related to the design characteristics of each fan form factor. Axial fans are known to sound high pitched and have high relative sound levels. Centrifugal fans are known to sound lower pitched and have moderate relative sound levels. Blowers are known to have a similar low pitched sound as centrifugal fans, but can have relatively high sound levels for high performance models. Knowing what sound signature each type of fan offers has a big effect on getting the best acoustic levels for the customer's product.