It's still hopelessly wrong, unless you need to think about how to spell Mississippi every time you say it.

Sound travels roughly a mile in five seconds. So you say whatever it is you need to say to pace your counting at one per second, then divide by five to get the distance in miles.

For me, the word "and" has always sufficed for this. "One-and two-and three-and four-and five-and" and that's a mile. When I was about 12, every time our scout pack got on the leaders' nerves too much she would make us stand in a circle and then sit down when we thought a minute had passed. She had to think of something else eventually, because I was able to reliably do it to within a second. It's accurate enough.

On a side note, I think you will find that this varies more person-to-person than region-to-region. Some people do it using the language-processing part of their brains (like you) while others do it using the visual part of their brain, picturing a clock ticking or something similar.