Done by 'sound forge' F.M synthesizer. Basically four added sine waves, each has some percentage of self-modulation(feedback). The sound effects chain applied over the initial sound is: reverb, chorus(or chorus, reverb, I don't remember), upward compression(sound forge wave hammer), pitch shift(down) and finally vibrato, to simulate a varying speed tape machine(to make it a bit older!)
Hornlike.wav
聲道：2
類型：wav
Sound、Forge、hornlike、synthetic
聲音、鍛造、角狀、合成的
資料來源：freesound ( https://freesound.org )