We did an experiment in London where we played recordings of phoneticians saying 'herb' very carefully, some with the /h/ and some without. Many listeners reported hearing the /h/ in them all, although vocal tract x-rays and voice prints etc could prove there was no /h/ in half of them.
Some heard no /h/ in any.
We never told them what we were testing for.
People often 'hear' what they are expecting to hear.