Tricky to answer in a precise way but here goes:
Lucifer’s voice is a mellow voice. If I hear it he communicates mostly through visual impressions.
Belial’s voice is a strange one it’s a deep, hissing voice similar to the skull door in Skyrim. That is if he speaks at all otherwise he’ll drop an imp
Azazel’s voice depends a bit from time to time. It sounds a lot like Kratos from God of War:
Amaymon speaks very little mostly communicates through imagery. If he ever says anything it sounds - bit like this:
Like the first part of the voice that supposedly speaks ancient Egyptian.
It’s the same echo effect and the tone is a bit more rounded.
Namaah sounds a lot like this
But just out of earshot.
Ahriman “voice” is well…soundless but it’s loud it’s really difficult to put into words.
Lillith makes voice sound a lot like the actress Ingrid Pitt, the Voice of Elisabeth Bathory. An example of how I perceive can be heard in this song from this band
https://youtu.be/y6RWLYkAY3Y
At 8:39
Then we have Hecate, her voice unless she shows you visions of what she was wants. Is very commanding yet is very much a silky alto voice.
Aigash - is like a crossover between the hissing voice of Belial and the “voice” of Ahriman. It’s like hearing a hissed whisper that’s filling your head from everywhere…
Freyja - sounds quite a good deal like Nariko in heavenly sword.
These are the spirits I can clearly recall hearing a clear “voice”. However, before that it was just telepathic words. Also they don’t have these voice all the time these voices changes it seems with what aspect or rather form the choose to come in.