Wemmie's studies have shown that these acid-sensing proteins are required for normal fear responses and for learning and memory in mice. However, while you can buy a kit to measure the acidity of your garden soil, there currently is no easy way to measure pH changes in the brain.
For the normal version of the english typing test we have calculated an average of 41 WPM, this value is based on over 73 million typing results. Considering that these words are relatively easy to type, the avg WPM is probably around 20-25 WPM for normal text with punctutations etc.
What qualifies as a good typing speed depends on the population you're examining: the general population or professionals. The average person types between 38 and 40 words per minute -- between 190 and 200 characters per minute. However, professional typists type a lot faster on average -- upwards of 65 to 75 WPM.