A voice from no one!

So, I’ve been told not to start sentences with the word so. So, I was walking along a quite narrow footpath recently when I heard a woman’s voice behind me saying ‘excuse me’. I walk slowly so I get this a lot. I was just approaching a junction in the path where I would turn off so I didn't bother getting out of the way immediately. Then it occurred to me the woman might be taking the same  branch route so I might still be in her way. So I looked around to see which way she was going only to see no one there! Oh!

So it had been no more than a second or two between hearing the voice and turning round. That would have been not have been enough time for the women to have turned back and left my field of view. The was a tall fence on one side of the path and a low one on the other. If she had stepped over the low fence she would still be visible in the low vegetation beyond. Going the other way, she'd still be climbing the high fence!

So, I heard a voice from someone who wasn’t there – a ghost perhaps? What alternative explanations are there? One thing I noticed straight after the incident was that there were lots of birds, from several species, calling from the tall fence side of the path where there was lots of tall vegetation. So, a possibility is formant noise (see here for explanation). If you look at the sonagrams of bird song some of it certainly resembles the formant structure of human speech. So it could certainly have been the noise from a number of different species of bird calling simultaneously  producing formant noise. As to the content, ‘excuse me’, as I said I hear it a lot in these circumstrances so expectation would play an important part.

While I’m used to formant noise as an explanation of at least some EVP it hadn’t occurred to me that people might be hearing it live, as opposed to in recordings. This could be another xenonormal source of ghostly voices.

PS: In mistyping the word ‘fence’ my spell checker introduced me the word 'renice' that I’ve never come across before! Can't think how I lived without it.