As the title suggests, I need help creating a particular sound effect for a film I am working on. An example of the effect I am looking for is at 1:40 in the link below;
Around 1:40 the patient (I forget the actors name) goes into a trance like state and you hear a ringing sound effect coupled with the doctors voice becoming echo-like.
I know the echo effect can be created by putting reverb on the dialogue track and slowly automating the dry/wet channel upwards, but I have no clue how to get a good 'ringing' sound to go along with it.
Does anyone have any experience on creating an effect like this? Please share!