Here’s a simple observation test that may interest you. Read the following sentence once and count how many times the letter “F” appears:
FINISHED FILES ARE THE RESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THE EXPERIENCE OF YEARS
So, how many F’s did you see? Some of you may say four, five or even six but many people would only count three. The first two words in the sentence suggest us to look for soft F’s. That’s why most people who missed the other F’s didn’t take into account hard sounding F’s that sounds like “V’s”. In the sentence above, that would be the word “of” which appears three times.