The Adult Top 40 (Adult CHR) format is a hybrid of Hot AC and Top 40 ( CHR). Unlike Hot AC stations, they air hip hop and R&B music that typical Top 40 (CHR) stations play. At the same time, unlike Top 40 they spin a large amount of adult-oriented 80s, 90s and current music heard on Hot AC stations. Most of these stations are usually classified as Hot AC stations by radio research companies such as Nielsen Audio, since the Adult Top 40 format is simply a hybrid of Hot AC and Top 40.