The first version of this piece I made using an EMS Synthi in the late 1960s. I had to do a lot of dubbing so that the result finished up with tape hiss and clipping in the louder parts.
Unfortunately I haven't yet located the tape reel so this version is based on memory only, and must vary from the original quite a lot.
The sirens are sea nymphs, part woman part bird, whose songs lure sailors to their deaths.
LT