TL/DR: I believe the Raspy Voice is a hallucinationThe raspy voice Cole hears without seeing its speaker is experiencing, like the voicesan audio hallucination akin to a voice heard by a schizophrenia suffererssufferer. Louie, the toothless time traveler, is a real person -- and after meeting Louie, Cole -- in a state of extreme mental fatigue -- retroactively associates the raspy voice with Louie.
FULL ANSWER: The raspy voice Cole hears without seeing its speaker is an audio hallucination akin to the voices heard by schizophrenia sufferers, who often describehave described the voices as "spoken by an external, commanding authority" (quote from New York Times article about schizophrenia).
Note below that in all fourthree scenes with the Louie/Rasping Voice characterraspy voice, the voice seems exactly like an external, commanding authority:. In scenes 1 and 4 below, the voice interrogates and castigates Cole, prompting Cole to defend himself. In scenes 2 and 3, the voice suggests that Cole might have a way out of his predicament, which Cole desperately wants to hear.
- first appearance (just voice)audio hallucination: when Cole has returned to 2025 after his first time mission
- second appearance (in human form)audio hallucination: when Cole is with Railly in 1997 and meets homeless manhas returned to 2025 after his second time mission
- "They got that tracking device on you... In the tooth, Bob! Right? But I fooled 'em, old buddy!" (reveals he has no teeth)
- third appearance (just voice) when Cole has returned to 2025 after his second time mission
- fourth appearance (just voice) when Cole is in the airport bathroom
- third audio hallucination: when Cole is in the airport bathroom
So in scenes 1, 3 and 4,This leaves the rasping voice is something Cole is hearing in his head -- in other words, an audio hallucination. In scene 2,where the voice/Louis appears to come from the homeless man Louie:
- Louie: "They got that tracking device on you... In the tooth, Bob! Right? But I fooled 'em, old buddy!" (reveals he has no teeth)
I believe Louie is telling the truth: he is a visual and audio hallucination. (I havetime traveller who has avoided returning to watch scene 2 againthe future by removing his teeth. At the same time, but I am pretty sure there is no clear evidence thatLouie's use of "Bob" and the way he seems to sound like the raspy voice is explained earlier by Railly also sees or hears Louis.when Cole tells her she is in his dream):
- James Cole: "I never knew it was you before."
- Kathryn Railly: It wasn't me before, James. It's become me now because of...what's happening."
On a related note, I believe there really was a tracking device in Cole's tooth. HeRailly was aware of it, either consciously or subconsciouslywrong then -- and the hallucination where Louis mentions tooth removal helps Cole realize or remember the tracking deviceit was her in his own teethCole's dream. But the phenomenon she describes does occur when after meeting Louie, Cole -- in a state of extreme mental fatigue -- retroactively associates the raspy voice with Louie.