Found the following article online, use it to answer the question: What does Beyoncé introduce by name as the song opens?  "Déjà Vu" is a contemporary R&B song, performed in a moderate hip hop groove. It is also influenced by late-1970s funk music, and it contains elements of soul music as well as dance-pop music. According to the sheet music published at Musicnotes.com by EMI Music Publishing, the song is composed in the key of G minor with a time signature in common time, and a moderate groove of 106 beats per minute. Beyoncé's vocals range from the note of D♯4 to F5. The music is largely based on live instrumentation, including a bass guitar, conga, hi-hat, and horns. A non-live instrument, the Roland TR-808 drum machine, provides the song's heavy and energetic disco beat. Spence D. of IGN Music commented that Beyoncé's vocals on the song are "silky smooth" and that her vocal range leans toward the high end, hence contrasting to the song's low-end construction. Mike Joseph of PopMatters noted that "Déjà Vu" is reminiscent of Michael Jackson's "Off the Wall" (1980). The title refers to the déjà vu phenomenon. The lyrics to "Déjà Vu" follow the verse–pre-chorus–chorus pattern, and feature two rap verses. It is hook-laden, similar in this respect to "Crazy in Love". The lyrics detail a woman being constantly reminded of a past lover, shown in the lines, "Is it because I'm missing you that I'm having déjà vu?" As the song opens, Beyoncé introduces the bass, hi-hat and Roland TR-808 by name. The sounds of the instruments blend as they are being mentioned one after the other; the horns are only audible in the pre-chorus and hook sections, and a short section in the second rap. The bass guitar, which is the first instrument to enter, slides into the main two-bar ostinato. Following the repeated bass slides, the hi-hat and the Roland TR-808 begin playing.After that Beyoncé mentions Jay-Z, the bass glides up for a vibrato-rich fill, giving way to the first rap. Backgrounded with a repeating groove, Beyoncé starts the first verse. The pre-chorus follows, for which the bass changes to a more melodic tone "to play something more singing",...
The answer to this question is:
hi-hat