The next time you're facing the bathroom mirror, try saying the words heat, hit, hat, hot. For the first two, your mouth will stay fairly closed, but for the last two, your tongue will move lower and cause your mouth to open wider. (The sounds of relaxation and pleasure typically contain lower vowels.) We can use a vowel chart, like Table 3.3 (based on Ladefoged and Johnson, 2011), to help classify the most common vowel sounds in English.