Hey Jude

Context: Having earmarked the song for release as a single, the Beatles recorded "Hey Jude" during the sessions for their self-titled double album, commonly known as "the White Album". The sessions were marked by an element of discord within the group for the first time, partly as a result of Ono's constant presence at Lennon's side, and also reflective of the four band members' divergence following their communal trip to Rishikesh in the spring of 1968 to study Transcendental Meditation. Author Peter Doggett describes the completed version of "Hey Jude" as a song that "glowed with optimism after a summer that had burned with anxiety and rage within the group".  The Beatles first taped 25 takes of the song at EMI's Abbey Road Studios in London over two nights, 29 and 30 July 1968, with George Martin as their producer. These dates served as rehearsals, however, since they planned to record the master track at Trident Studios to utilise their eight-track recording machine (Abbey Road was still limited to four-tracks). A take from 29 July, which author and critic Kenneth Womack describes as a "jovial" session, was issued on the Anthology 3 compilation in 1996.  The 30 July rehearsals were filmed for a short documentary titled Music! However, the film shows only three of the Beatles performing "Hey Jude", as George Harrison remained in the studio control room, with Martin and EMI recording engineer Ken Scott. Author Simon Leng views this as indicative of how Harrison was increasingly allowed little room to develop ideas on McCartney compositions, whereas he was free to create empathetic guitar parts for Lennon's songs of the period.  During the rehearsals that day, Harrison and McCartney had a heated disagreement over the lead guitar part for the song. Harrison's idea was to play a guitar phrase as a response to each line of the vocal, which did not fit with McCartney's conception of the song's arrangement, and he vetoed it. In a 1994 interview, McCartney said, "looking back on it, I think, Okay. Well, it was bossy, but it was ballsy of me, because I could have bowed to the pressure." Ron Richards, a record producer who worked for Martin at both Parlophone and AIR Studios, said McCartney was "oblivious to anyone else's feelings in the studio", and that he was driven to making the best possible record, at almost any cost.  Scott, Martin and the Beatles mixed the finished recording at Abbey Road. The transfer of the Trident master tape to acetate proved problematic due to the recording sounding murky when played back on EMI's equipment. The issue was resolved with the help of Geoff Emerick, whom Scott had recently replaced as the Beatles' principal recording engineer. Emerick happened to be visiting Abbey Road, having recently refused to work with the Beatles any longer, due to the tension and abuse that had become commonplace at their recording sessions. A stereo mix of "Hey Jude" was then completed on 2 August and the mono version on 8 August.  Everett writes that the song's "most commented-on feature" is its considerable length, at 7:11. The precedent for issuing such a long track on a single had recently been set by Richard Harris' hit recording of "MacArthur Park", the composer of which, Jimmy Webb, was a visitor to the studio around this time. According to Webb, Martin admitted to him that "Hey Jude" was only allowed to run over seven minutes because of the success of "MacArthur Park".  In the song's final bridge section, at 2:58, the spoken phrase "Fucking hell!" appears. Scott admits that although he was told about it, he could not hear the words originally. Lennon attributed the expletive to McCartney, according to Emerick, who reports Lennon's comment in his autobiography: "'Paul hit a clunker on the piano and said a naughty word,' Lennon gleefully crowed, 'but I insisted we leave it in [at Trident], buried just low enough so that it can barely be heard. Most people won't ever spot it ... but we'll know it's there.'" Womack considers that the expletive was actually uttered by Lennon. Malcolm Toft, the mix engineer on the Trident recording, also attributes it to Lennon. In Toft's recollection, Lennon was overdubbing his harmony vocal when, in reaction to the volume being too loud in his headphones, he first called out "Whoa!" then, two seconds later, swore as he pulled the headphones off.  "Hey Jude" begins with McCartney singing lead vocals and playing the piano. The patterns he plays are based on three chords: F, C, and B (I, V and IV). The main chord progression is "flipped on its head", in Hertsgaard's words, for the coda, since the C chord is replaced by E. Everett comments that McCartney's melody over the verses borrows in part from John Ireland's 1907 liturgical piece Te Deum, as well as (with the first change to a B chord) suggesting the influence of the Drifters' 1960 hit "Save the Last Dance for Me".  The second verse of the song adds accompaniment from acoustic guitar and tambourine. Tim Riley writes that, with the "restrained tom-tom and cymbal fill" that introduces the drum part, "the piano shifts downward to add a flat seventh to the tonic chord, making the downbeat of the bridge the point of arrival ('And any time you feel the pain')." At the end of each bridge, McCartney sings a brief phrase ("Na-na-na na ..."), supported by an electric guitar fill, before playing a piano fill that leads to the next verse. According to Riley, this vocal phrase serves to "reorient the harmony for the verse as the piano figure turns upside down into a vocal aside". Additional musical details, such as tambourine on the third verse and subtle harmonies accompanying the lead vocal, are added to sustain interest throughout the four-verse, two-bridge song.  The verse-bridge structure persists for approximately three minutes, after which the band leads into a four-minute-long coda, consisting of nineteen rounds of the song's double plagal cadence. During this coda, the rest of the band, backed by an orchestra that also provides backing vocals, repeats the phrase "Na-na-na na" followed by the words "hey Jude" until the song gradually fades out. In his analysis of the composition, musicologist Alan Pollack comments on the unusual structure of "Hey Jude", in that it uses a "binary form that combines a fully developed, hymn-like song together with an extended, mantra-like jam on a simple chord progression".  Riley considers that the coda's repeated chord sequence (I-VII-IV-I) "answers all the musical questions raised at the beginnings and ends of bridges", since "The flat seventh that posed dominant turns into bridges now has an entire chord built on it." This three-chord refrain allows McCartney "a bedding ... to leap about on vocally", so he ad-libs his vocal performance for the rest of the song. In Riley's estimation, the song "becomes a tour of Paul's vocal range: from the graceful inviting tones of the opening verse, through the mounting excitement of the song itself, to the surging raves of the coda". CANNOTANSWER

Question: What is an interesting feature regarding the structure of the song Hey Jude?
Answer: Hey Jude" begins with McCartney singing lead vocals and playing the piano. The patterns he plays are based on three chords: