The rise of popular music on a global scale has prompted researchers to predict standard features for creating the next hit songs. Previous studies have explored various acoustical/audio features and their relations to top-charting songs but fail to include the artists' voice in determining popular music patterns. As a result, this study had used a trend analysis to find consistent patterns over the selected period (1980-2019) by analyzing five distinct vocal features: vowel corruption, pitch, intensity, number of pulses, and voicing. Upon analyzation, a general increase in vowel corruption and a formant difference in vowels were observed. A stagnant level in intensity and extreme variation in pitch was also noted. Overall, this study was one of the first to find accurate trends, including vocal features in hit song prediction research. Among various implications, one would be introducing a new area of study regarding singing in contemporary music.