The Javelin was noted for its distinctive booming engine sound, resulting in one of its nicknames being 'Harmonious Dragmaster'.
I think that the reason for this peculiar sound was the long tubular air intakes ahead of the engine, causing an effect rather like an organ pipe.
Here is a recording made back in the fifties when they certainly knew how to make an impression at an airshow - twenty seven Javelins doing a fly past!
The posh commentator announced "...three formations of Jevlinz" and right on cue they flew overhead, treating everybody to the sound of 54 Sapphire engines. You can clearly make out the three separate diamond-nine formations as they pass overhead.
My thanks to Bill Earl who has kindly provided this recording.
The size of the file is 765 KB.
Click on the link below to hear it.
Javelins in Motion

A rare colour movie file, where a Javelin performs a nice aileron roll
File size is 1.2 MB.
Click on the link below to see it in your default movie viewer.