A sound suppression apparatus for installation inside a gas transport duct, the sound suppression apparatus comprising: a resistive sound-absorbing element; and a housing providing a reactive sound-attenuating element communicating with a surrounding of the apparatus via an opening (131a, 131b) in an outer surface of the housing; wherein: the sound suppression apparatus has an elongate form in a longitudinal direction from the first end of the sound suppression apparatus to the second end of the sound suppression apparatus; the outer surface of the sound suppression apparatus is shaped to provide aerodynamic gas flow from a first end to a second end of the sound suppression apparatus; the housing has a profile in a plane including the longitudinal direction which tapers in the longitudinal direction towards the second end of the sound suppression apparatus characterised in that: the outer surface of the sound suppression apparatus comprises an outer surface of the resistive sound-absorbing element and the outer surface of the housing; and the resistive sound-absorbing element is arranged relatively closer to the first end of the sound suppression apparatus than the housing. a resistive sound-absorbing element; and a housing providing a reactive sound-attenuating element communicating with a surrounding of the apparatus via an opening (131a, 131b) in an outer surface of the housing; wherein: the sound suppression apparatus has an elongate form in a longitudinal direction from the first end of the sound suppression apparatus to the second end of the sound suppression apparatus; the outer surface of the sound suppression apparatus is shaped to provide aerodynamic gas flow from a first end to a second end of the sound suppression apparatus; the housing has a profile in a plane including the longitudinal direction which tapers in the longitudinal direction towards the second end of the sound suppression apparatus characterised in that: the outer surface of the sound suppression apparatus comprises an outer surface of the resistive sound-absorbing element and the outer surface of the housing; and the resistive sound-absorbing element is arranged relatively closer to the first end of the sound suppression apparatus than the housing. the sound suppression apparatus has an elongate form in a longitudinal direction from the first end of the sound suppression apparatus to the second end of the sound suppression apparatus; the outer surface of the sound suppression apparatus is shaped to provide aerodynamic gas flow from a first end to a second end of the sound suppression apparatus; the housing has a profile in a plane including the longitudinal direction which tapers in the longitudinal direction towards the second end of the sound suppression apparatus characterised in that: the outer surface of the sound suppression apparatus comprises an outer surface of the resistive sound-absorbing element and the outer surface of the housing; and the resistive sound-absorbing element is arranged relatively closer to the first end of the sound suppression apparatus than the housing. the outer surface of the sound suppression apparatus comprises an outer surface of the resistive sound-absorbing element and the outer surface of the housing; and the resistive sound-absorbing element is arranged relatively closer to the first end of the sound suppression apparatus than the housing.