Neighbour has given me a spare cone to try, which is a slightly different shape. This has reduced the noise a little and also changed the type of sound.
I'm sure you are right, that the noise is caused by the fast water flow through the valve and every valve seems to be different.
I changed the original valve as the cone end was damaged and not shutting off, so maybe this is why it was quieter.
I will look at your suggested alternatives and if the noise becomes unbareable, will try one of these replacements.
Thanks for all your help.