Authors:
Ricardo N. Futre Pinheiro (Escola Superior de Música de Lisboa, Instituto Politécnico de Lisboa)
Alexandre H. de Sousa Diniz (Faculdade de Arquitectura e Artes, Universidade Lusíada de Lisboa)

In 2007, Herbie Hancock's River: The Joni Letters won two Grammy Awards: one for album of the year and one for best contemporary jazz album. Jazz critic John Kelman (2007) claims that this album is "unequivocally jazz", in comparison with Hancock's former release Possibilities, which is labeled by Kelman as an "unapologetically pop record" (ibid.). Kelman's categorization suggests the existence of a clear border between two musical realms. The boundaries that delimitate jazz as a concept, implied in the discourse of musicians and other members of the milieu, have been extensively debated, particularly by authors that discuss the definition of jazz as a musical genre (Ake, 2002; Berliner, 1994; Gridley, Maxham, & Hoff, 1989; Jackson, 2002; Martin, 1986; among others). According to Thom Jurek in the website allmusic.com, Possibilities (2005) is a Herbie Hancock's album that fits in the jazz and pop-rock categories, even though he claims that "Jazz fans may be disappointed, but pop fans will be delighted; there is a lot here to like" (Jurek, n.d.). According to John Kelman (2005), this album has a very diverse sonority "and with Hancock in a truly collaborative mode, it sounds unlike anything he has done before".

The goal of this article is to provide a comparative analysis between these two albums. Both are musically led by Herbie Hancock; both contain music written by songwriters who are not identified by the critics as 'jazz musicians'; and both include vocal music interpreted by prominent guest artists from the pop-rock realms. If both albums share these features, what makes one "unequivocally jazz" and the other "unapologetically pop"? The answer for this question might contribute to deepen the discussion of the construction of the concept of jazz.

The methodology employed in the comparison between the two phonograms is based on the approach developed by David Ake in Jazz Cultures (2002). In the chapter "Jazz Traditioning", Ake confronts two different albums by Wynton Marsalis and Bill Frisell, exploring how each one is labeled according to certain aesthetic, evaluative, and normative constructions of the jazz tradition. Ake points three main criteria as foundations for his analysis: 1) who plays the music? 2) which songs are played? 3) how the music is played? (2002, p. 147). Departing from these three categories, we will analyze the concept and the features of the repertoire of each album, the instrumentation and the musical background of the participant musicians, and discuss the processes that involve the creation of the arrangements, performance and recording.

The debate on jazz as a tradition

The discussion on what can or can't be considered jazz has been extensively dis- cussed in literature. According to Prouty (2012) "The boundaries of jazz have long been discussed and debated in the pages of magazines, newspapers, and journals, and in films and other media, as critics, scholars, and musicians have expressed opinions on what qualifies as real jazz" (p. 70). According to Tucker (2012), "In jazz studies, as one can see quickly by reading recent titles of books, articles, and conference papers, many of us are not content to shore up a cohesive singular narrative about jazz, but we have been asking about the musics that were called jazz but are not called jazz now" (p. 276). Ake, Garrett, and Goldman (2012) believe that the processes of labeling music according to its musical style and genre have a fundamental role in the way jazz is taught, learned, created, evaluated and accessed (Ake et al., 2012, pp. 3-4).

The richness and diversity of the musical, aesthetical, and technical approaches that developed throughout history make strict definitions of jazz very problematic (Gridley et al., 1989). For that reason, the establishment of a set of criteria functioning as a foundation for the development of a definition of jazz becomes a very complex and multi-dimensional task. Charles Hersh (2008) discusses the problems with the concept of jazz tradition and distinguishes two groups of people with divergent perspectives. For one side, Hersh identifies people who see jazz as a tradition connected to a particular group of musicians, compositions, iconic recordings, practices and stylistic features that evoke early jazz, rooted in the blues and swing aesthetics - the "neotrads" (2008, p. 7). On the other hand, Hersh identifies the "antitrads", who oppose to any closed concept of tradition, and defend that a narrow perspective on jazz suggests a hegemony, exclusivity and restrictiveness that are artificial. The "antitrads" conceive jazz as something open to stylistic and cultural diversity. Hersh postulates that the discourse on an alleged evolutive tradition of jazz is relatively recent (p. 9), starting to develop in the end of 1960's, based on the ideas of writers such as Mar- tin Williams and Gunther Schuller. Wynton Marsalis, as the artistic director of Jazz at Lincoln Center in New York, stood out as a "neotrad" after continually programming sets of concerts that refer to a traditional canon, and affirming publicly the determination to "recover" and keep "authentic" and intact the jazz tradition, saving it "from dumbing-down and pop opportunism" (Nicholson, 2005, p. 24). According to Hersh, "by the 1980s Wynton Marsalis, drawing on the ideas of Albert Murray and Stanley Crouch, became the public face of a 'new traditional- ism' championing the work of Armstrong, Ellington, and others as part of a well- defined tradition" (2008, p. 9).

As representations of anti-traditionalism, Hersh points out the works of Scott DeVeaux, Krin Gabbard, David Ake and Sherrie Tucker. These perspectives imply a broader concept of jazz, or even in some cases, its complete rejection. However, in the scope of this discussion, it is crucial also to consider political, cultural and racial motivations, besides the obvious musical aspects. Charles Hersh (2008) accuses neo-traditionalists of underestimating innovation (p. 10), of being anti-democratic (p. 13) and elitists (p. 14). On the other hand, he labels anti-traditionalists as self- contradictory - "the idea of an open tradition is an oxymoron" (p. 19) - accusing them of overlooking the risks of an excessively broad concept of jazz (p. 20), and of being evasive in terms of establishing borders, even when they recognize these as necessary.

Although Ake et al. (2012) present an open understanding of a set of different styles and musical practices that can be regarded as 'jazz', they also acknowledge the dangers of falling into a radical relativism in the concept's construction process:

We accept that viewing jazz as an open-ended, multifaceted, ever-changing idea or set of discourses, rather than a prescribed and proscribed set of musical devices, names, places, or styles opens the door for charges of radical relativism: if anything and anyone can be seen, heard, or described as jazz, then the category becomes meaningless. (...) Jazz covers immense terrain, sonic and otherwise, but it does not extend everywhere (Ake et al., 2012, p. 6).

Hersh, in the context of his critique of anti-traditionalists' assumptions, states however that identifying musical aspects associated with jazz can contribute as a "large step in defining a discrete tradition" (2008, p. 19).

Possibilities - the concept

The key concept of the album Possibilities rests on the choice of the participant artists, without any previous selection of repertoire (Hill, 2005). The main idea is to explore the musical possibilities that emerge from artistic collaboration between performers. According to Michael Hill in the album's liner notes: "Just the desire to find performers, who, like him [Herbie Hancock], might be eager to step away from defined roles or familiar territory, and make a creative leap of faith" (2005). Hill tries to convey the idea that this album is a product of 'authentic' collaborations that result from physical and creative proximity: "Forget long distance digital alchemy or disembodied duets, this one's all about face to face, heart to heart, real to reel" (ibid.). We can argue that, by stressing the album's alleged authentic character, Hill is implicitly criticizing the typical modus operandi of pop music recording and production processes, characterized sometimes by the lack of synchronic physical interaction between musicians or other participants in the process. Although there's synchronic physical interaction between these musicians, each one of the ten tracks was recorded in a different studio, with different people involved.

Possibilities - the instrumentation and the musicians

Ake (2002) points out that the analysis of an album's instrumentation can be crucial for the discussion of its cultural references (p. 156), while Hersh (2008) states that the performance instrumentation can serve as fundamental criterion for its connotation (or lack of) with the jazz tradition. In Possibilities, every Hancock's improvised solo is played on the acoustic piano. However, only two tracks don't include electric or electronic keyboards: "I Do It for Your Love" - a song Hancock considers more jazz sounding (Hill, 2005) - and "Don't Explain", a composition co-authored by Billie Holiday.

Besides "Sister Moon", recorded with acoustic double bass, only one track - "I Just Called to Say I Love You" - doesn't have electric bass. In this piece Hancock uses electronic elements extensively, and every sound that resembles a rhythm section is electronically generated, including the bass. According to some "strict definitions of jazz" (Gridley et al., 1989), the use of the acoustic double bass instead of the electric bass is a culturally significant aspect in terms of instrumentation and can become an important criterion in the discussion over 'what is jazz'. The presence of the electric guitar is very noticeable in the album's first two songs. Guitarists John Mayer and Carlos Santana are the first two guests here. Even though both are improvisers, they will hardly be depicted as 'jazz musicians' by jazz critics. Their approach to improvisation is based on blues and rock elements, not only in terms of timbre, but also in the articulation and phrasing. The same applies to Jonny Lang, the guitarist in "When Love Comes to Town". Paul Simon's acoustic guitar, inspired by the American folk tradition, assumes it's expected role with a discreet accompaniment in "I Do It for Your Love". The acoustic guitars in "Hush, Hush, Hush" (collabo- ration with Annie Lennox) and "I Just Called to Say I Love You" (collaboration with Raul Midón) also assume a very subtle character.

In this album, the drum kit spans a wide specter of styles, both in terms of timbre and the way it is played. It is used in every song, except in "I Just Called to Say I Love You", where the rhythms are electronically generated. The way the drum kit is played will be discussed in the following section of this paper. Percussion functions as a complement to the drums, contributing to the construction of timbres and textures in the rhythm section. Although it emerges in jazz history via latin jazz (Davis, 2012, p. 5), percussion is not common in bebop, hardbop, or cool jazz recordings. Half of the songs in Possibilities have percussion.

According to Herbie Hancock in his autobiography, "Possibilities was the first one [album] I did in which all the songs had lyrics" (Hancock & Dickey, 2014, Chapter 23). Vocals are predominant in this album and Hancock invited singers from musical areas other than jazz, knowing that he was selecting prominent pop-rock names that would likely attract the attention of a wider public. This fact is also relevant for the categorization process of Possibilities as a jazz or 'non-jazz' album. In the following section, we will analyze the interpretative aspects of this recording.

Possibilities - the performances

In some moments of this album, it is noticeable that the invited artists are trying to musically transcend their comfort zone. In other instances, they are merely replicating what they usually do while performing with their own projects. When this hap- pens, Hancock is the one who tries to adapt to the others' musical approach.

"A Song for You" is a 'non-jazz' African-American standard with a clear soul and R&B character, which is prone to vocal virtuosic demonstrations. Christina Aguilera's interpretation refers to the history of the song and its key performers (Donny Hathaway, Ray Charles, Cher, Whitney Houston), while Hancock, as elsewhere in the album, brings a more interactive musical approach. Similar moments occur during the album, namely the collaborations with Carlos Santana and Angélique Kidjo, Jonny Lang and Joss Stone, and Raul Midón. The session with Carlos Santana and Angélique Kidjo sounds as if it was taken from a typical Santana album. The musical approach, timbres, rhythms and the sound of Santana's guitar are unmistakable. In this song, everything sounds like Santana, except Hancock's improvised solo that starts at minute 3:13. Listening to this track out of context can create the illusion that Herbie Hancock is Santana's guest and not the other way around.

Jonny Lang and Joss Stone also perform in a 'safe area'. "When Love Comes to Town" is performed in a slower tempo than the original U2 version (Rattle and Hum, 1988), but Lang's guitar keeps the same blues register as B.B. King's in the original recording. In his solo, Herbie Hancock creates complex rhythms and uses more chromaticism when compared to his guests, who use essentially soul and blues-rock melodic motifs.

Stevie Wonder's "I Just Called to Say I love You" features an electronic arrangement and a more daring harmonization. However, Raul Midón's interpretation is stylistically close to Stevie Wonder's original. In the second half of the song, an electronic percussion with a soft pop-rock rhythmic pattern emerges, just before a joint solo by Herbie Hancock and Stevie Wonder himself.

In the remaining tracks, it is possible to observe greater distance between guest artists and their comfort zone. For example, the opening track was created in the studio from a rhythmic idea by John Mayer. Although he doesn't consider himself a "jazz musician" (Fricke, 2007), this procedure resembles the process of a jazz studio recording. "Stitched Up" developed spontaneously, with impro- vised words and melodic ideas that were being written down on the spot. Mayer's arrangement, even though with a pop-funk rhythmic character, is loose and light, providing enough space for Hancock's musical commentaries during his comping.

"Don't explain", by Arthur Herzog and Billie Holiday, is interpreted by Damien Rice e Lisa Hannigan. This song is performed like a classic jazz ballad, with the piano comping alone the beginning of the melody exposition. Later, the drums, played with brush sticks, and the bass join in, creating a typical jazz rhythm section texture. In the middle of the form, there's a small cello solo, an uncommon instrument in this kind of musical context.

"Hush, Hush, Hush" features a compound meter, a medium/slow groove and a sophisticated harmony. The song begins with a free piano introduction by Hancock, that latter becomes a 12/8 groove. Annie Lennox's voice enters accompanied initially only by the piano. The rhythm section and the guitar join in later, with a subtle, free and interactive feel. Some keyboards appear at 2:50, bringing a cinematographic atmosphere to the song. From here on, the performance starts to develop into what could have been an extended Herbie Hancock's solo, but a fade out brings the song to an end.

In this album, British musician Sting interprets his own "Sister Moon", built on an insistent 12/8 vamp performed by the bass, guitar, keyboards and drums. The arrangement involves a polyrhythmic character that spans across the whole track. Piano and percussion fill the spaces interactively, while Sting interprets the melody. At 3:07, Herbie Hancock starts an improvised solo on the main vamp, using complex rhythms and a considerable amount of chromaticism. In the last two minutes of the song, the musicians - including Sting - explore some group improvisation.

The collaboration with Paul Simon is considered by Hancock as one of the songs in Possibilities that sounds more like "jazz" (Hill, 2005). "I Do It for Your Love" has a more harmonically dense arrangement than the original. It starts with a free piano introduction, after which Simon exposes the melody alongside Hancock's freely improvised short melodies, with no settled tempo. After 2:18, the drums and two percussion kits build a hypnotic feel, with an African influenced compound meter, and set the mood for Hancock's piano solo. The whole performance sounds acoustic and smooth, without the rhythmic rigidity of rock, accomplished with a soft touch of African rhythms. Hancock's piano delivers a sophisticated texture.

We can argue that in the whole album, the most distinctive jazz element is Herbie Hancock's musical approach to piano playing. In some moments, what happens around him lacks stylistic cohesion. In other instances of Possibilities, the arrangements and the participant musicians contribute to a collective sound that can be associated with jazz. Given the nature of the concept of diversity that Hancock explores by putting together this album, the result would hardly be other than a mixture of styles and textures.

River: The Joni Letters - The concept

Just like in Possibilities, Hancock's main purpose in River: The Joni Letters was to explore, with several guest singers, Joni Mitchell's poems and songs. However, unlike the previous recording, this album doesn't have liner notes explaining its concept. In the case of River: The Joni Letters, this information is contained in Hancock's autobiography: "Her lyrics were the driving force, but the music was the stylistic creation of the band and the guest vocalists" (Hancock & Dickey, 2014, Chapter 23). Only two songs weren't written by Mitchell: "Nefertiti" by Wayne Shorter and "Solitude" by Duke Ellington. Besides these two instrumentals, there are two more voice- less tracks - "Both Sides Now" and "Sweet Bird". In a total of ten tracks, four are instrumentals. By contrast, in Possibilities, only one track is instrumental. The guest singers in this album are Norah Jones, Tina Turner, Corinne Bailey Rae, Luciana Souza, Leonard Cohen and Joni Mitchell herself.

River: The Joni Letters - The instrumentation and the musicians

In River: The Joni Letters, the same group of musicians plays in the entire album: Dave Holland on double bass, Vinnie Colaiuta on drums and Lionel Loueke on guitar, who had already recorded one track in Possibilities. For the saxophone, the invitation was addressed to renowned musician Wayne Shorter. The instrumentation of piano, double bass and drums, along with Shorter's saxophone, form a traditional jazz quartet. In some of the tracks, these instruments are joined by the guitar. There aren´t any keyboards or electronic instruments and there is no electric bass nor cello. According to Jackson (2002) "Small ensembles consisting of saxophone, trumpet, piano, acoustic bass and trap drum set, or big bands featuring choirs of trumpets, trombones and saxophones, are indelibly associated with jazz" (p. 89). Also David Ake (2002) refers instrumentation as a cultural meaning element: "Musical instruments not only produce sound; they also articulate cultures. . . . In jazz, the trumpet and the saxophone most signal the genre" (p. 156). Barry Kernfeld, quoted by Ake, describes the instrumentation in jazz as a "circumscribed body of instruments" (ibid.). While discussing the instrumentation in Wynton Marsalis's album Standard Time, Ake considers the quintet formed by trumpet, saxophone, piano, double bass and drums as a "marker of genre 'purity' for many contemporary jazz musicians and listeners" (2002, p. 157). We believe that the acceptance of River: The Joni Letters as a 'jazz album' by certain critics is partially related to the use of a more 'traditional' instrumentation.

River: The Joni Letters - the performances

This album has a very homogeneous sound. Most of the tempos are slow or medium, the drums are mostly played with brush sticks, the rhythm section is dynamically restrained, and the music has an introspective character. The album starts with a free piano introduction that provides a melancholic ambience and leads to the song "Court and Spark". The remaining rhythm section and the guitar come in later to establish the tempo and general mood of the song. The drums are played with brush sticks emphasizing even-eighths subdivision, the bass lines are strong tempo- anchored, and the guitar improvises some long note effects, leaving substantial space for the piano and voice to come in later. In this song, the guest artist is Norah Jones, frequently mentioned in debates on the establishment of boundaries in jazz. After the first section of the song, Wayne Shorter's soprano saxophone comes in to make minimalistic comments. The whole band plays in a loose way, without rigidity imposed by rhythmic patterns, interacting and finding space in the performance. The performance is simultaneously interactive and contained. For example, Shorter, in his first remark, plays just some isolated notes, without ever building a complete melody. The arrangement has several solo sections, featuring Shorter, Hancock, and in the end, the whole band.

Other songs, such as "River" sung by Corinne Bailey Rae, or "Amelia", by Luciana Souza, are characterized by the absence of solo sections. Nevertheless, Hancock and Shorter improvise through the entire performance, commenting and creating an interactive accompaniment along with the voice. "Edith and The Kingpin", sung by Tina Turner, and "Tea Leaf Prophecy", by Joni Mitchell, follow the same scheme as "Court and Spark", with open sections of improvised solos, but without having prolonged or intense improvisations. The improvised solos are always played by Hancock or Shorter, which is unusual for a jazz album. Because of the way they are played, instrumentals "Both Sides Now", "Sweet Bird", "Nefertiti" and "Solitude", could appear in any other Herbie Hancock's or Wayne Shorter's acoustic jazz album.

Discussion

Possibilities and River: The Joni Letters were recorded with a two-year gap. Both albums present originally pop-rock repertoire; feature renowned guest singers from non-jazz genres; and were musically oriented by Herbie Hancock. However, there are certain differences between them that cause an impact in the way they are ascribed to a certain musical genre by critics, musicians and other agents in the jazz milieu.

There's no doubt that Herbie Hancock's approach is deliberately different in both albums. In Possibilities, there's an exploration of improbable situations of collaboration between the pianist and a group of guest artists. There isn't a compromise of style: diversity and heterogeneity are welcome. Hancock travels musically through different areas and genres, overpassing boundaries, in search for some kind of musical globalization. This concept was further developed in The Imagine Project, released in 2010.

River: The Joni Letters was recorded after Possibilities and is - according to Hancock (Hancock & Dickey, 2014, Chapter 23) - radically different. This time, by previously exploring the texts from Joni Mitchell's songs, Hancock developed a different concept. Besides focusing on the repertoire of just one author, the band remains the same throughout the entire album and features renowned jazz musicians. Although Hancock plays piano in both albums, in Possibilities he also plays keyboards. In River: The Joni Letters the sound is deliberately acoustic, except for the electric guitar which, nevertheless, is subtle in the entire album.

The repertoire in Possibilities was not pre-established. Two of the collaborations resulted in two new compositions, created on the spot. The remaining collabo- rations used as material, songs from the non-jazz repertoire and, depending on the guest artist, ended up with an arrangement more or less filled with jazz elements. The arrangements were accommodated to each different guest.

The repertoire in River: The Joni Letters is also, in its majority, from a non-jazz origin. However, Joni Mitchell's biography reveals her proximity to this music. As Hancock recognizes, Mitchell's music "had the basic elements of jazz already in place" (Hancock & Dickey, 2014, Chapter 23), which suggests that his plan, this time, was to create a jazz album.

It is relevant to recall Whitesell (2008) as he tries to make clear that not all popular music is made with commercial purposes. The author criticizes the processes and discourses of a cultural prestige categorization based in the distinction between "high and low art" (p. 4). According to Whitesell, 'high art' relates to the classical music of western tradition, while 'low art' comprises popular music produced and commercialized by the music industry for the masses. Whitesell states that these categorizations of cultural prestige act like "preconceptual filters, sorting artists into piles marked from the start as 'superior' and 'inferior' before engaging with their work on its own merits" (2008, p. 4). He also refers that Joni Mitchell's music has been classified as a "legitimate art form" since the early days:

As Bernard Gendron has demonstrated, this general situation underwent changes in the 1960s, when certain popular musicians (notably the Beatles and Bob Dylan) began to acquire the status of serious artists rather than mere entertainers, and rock itself began to gain respect as a "legitimate art form". Arriving on the heels of this advancement in status, [Joni] Mitchell was able to overcome the lowbrow distinction to a limited extent. Already early in her career, critics were describing her music in terms of an art song aesthetic (Whitesell, 2008, p. 4).

The attribution process of 'cultural prestige' to Mitchell's music helps accommodating River: The Joni Letters in a more 'serious' setting. The discourses on 'high art' and 'low art', resulting from the construction and adoption of evaluative and normative criteria, are also evident in the jazz world (Berliner, 1994; Feld, 1988; Jack- son, 1998, 2002; Monson, 1996; Pinheiro, 2011, 2012). The participation of Christina Aguilera in Possibilities, for example, can be regarded by the more conservative critics (or "neotrads") as part of a commercial strategy, due to her pop-star status. This fact can be crucial for explaining the difficulty critics find in accepting this collaboration as 'jazz'. On the other hand, we can argue that for some, Joni Mitchell's name validates the ability of jazz to open its doors to pop-rock music without 'discrediting' its status as an alleged 'high art genre' in the non-classical music context.

A similar phenomenon can occur in terms of the choice of guest singers in both albums. Most of them have musical careers outside the jazz world. But a deeper analysis reveals that the singers in River: The Joni Letters, besides Joni Mitchell, are: Norah Jones, whose albums are catalogued as jazz in certain contexts; Corinne Bailey Rae, a renowned British soul music singer, with access to festivals and radios with a more commercial vocal jazz orientation; Luciana Souza, a singer whose work is somewhere between Brazilian popular music and contemporary jazz, with access to these same channels; Leonard Cohen, a singer-songwriter, poet and writer, with a similar musical career as Mitchell's, that started also in the United States in the 60's. Tina Turner is undoubtedly the album's most unexpected guest. Nevertheless, both the guest artists' profiles and the music performed in River, might fit in an elitist and prestigious popular culture ideal, positioned somewhere between jazz and 'high art song'.

Regarding the instrumentation, in Possibilities diversity is once more a crucial feature. Besides Herbie Hancock's piano, most of the tracks have keyboards and several other electronic sounds, used also as percussion and bass. It is also notice- able the predominance of the electric bass in the majority of the tracks; the strong presence of the electric guitar with distortion; the acoustic guitar; and the percussion kit. In River: The Joni Letters, the instrumentation is constant throughout the album. There are no electric or electronic keyboards; Wayne Shorter's saxophone is almost always present (in Possibilities there is no saxophone); Dave Holland's double bass is the only bass instrument (there are no electric or synthesized basses); Lionel Loueke's electric guitar appears in a subtle way, with a spacey and ethereal approach; and the percussion kit is totally absent.

The drummers' musical approach is different in both albums. In a general way, the collaborations in Possibilities that are closer to jazz have the drum kit played loosely in the different pieces, with the basic time keeping and the subdivisions played in the mounted cymbals, with soft dynamics, frequently with brush sticks. In the tracks that are closer to rock, pop, or funk, the drums are played in a stiffer way, with the purpose of providing the rhythmic drive for the performance, through repeated patterns supported basically in the three main pieces - bass drum, snare drum and hi-hat cymbals. The many different approaches to playing drums in jazz and rock are difficult to delimit but, in a general way, some basic differences like the ones described here can denounce the musical direction of the performance and the listeners' perception. In River: The Joni Letters, the drums are played constantly with brush sticks. We can argue that Vinnie Colaiuta's approach in this album fits the realm of jazz drumming iconic performances.

Among the wide number of musicians that play in Possibilities we can highlight, for example, Steve Jordan or Greg Phillinganes. The presence of musicians that are best known for participating in many pop albums - the so-called session musicians - can contribute to the idea that this recording lacks an organic group sound, resembling mass-produced records without 'greater' artistic concerns. For many members of the jazz community, the commercial success of pop music is linked to an alleged lack of musical and artistic identity. These qualities are much appreciated in jazz and this fact encourages the construction and development of a unique artistic voice among its musicians (Berliner, 1994; Jackson, 1998; Monson, 1996). Based on this premise, to the critics' ears, some performances in Possibilities face the risk of sounding too 'stereotyped'. This aspect may represent an important criterion for the recognition of this as a 'jazz album'. In River: The Joni Letters, not only the musicians are the same in the entire album, as their choice took in account their own musical status in the jazz community, especially in the cases of Dave Holland and Wayne Shorter.

While River: The Joni Letters is not an entirely vocal album (has four instrumental tracks), Possibilities presents itself as totally vocal, with an added instrumental track in the end. The more homogeneous sound of River: The Joni Letters is sup- ported by the choice of voices that feature a musical and expressive accent much closer to jazz. In Possibilities, the voices and interpretations of Christina Aguilera or Raul Mídon, for example, are highly aligned with R&B, soul and pop. In fact, this album has several moments in which the overall sounding of certain collaborations ends up leaning more into the guest artist's musical area. As examples, we can name the collaborations with Carlos Santana and Angélique Kidjo, or with Jonny Lang and Joss Stone. In these cases, the overall sounding is much closer to the music usually performed by these artists and farther away from the jazz of River: The Joni Letters.

Conclusion

Herbie Hancock's albums Possibilities and River: The Joni Letters share several common elements. However, if the latter is indisputably a jazz album, acclaimed by the critics and awarded as such, the former is not usually acknowledged by the jazz community. The definition of jazz and the placement of its boundaries aren't con- sensual and are subject to constant debate. The genre classification of an album like Possibilities faces a similar problem: of staying close to the boundaries of jazz for some, and beyond borders for others.

Eventually, instead of asking if Possibilities is a jazz album, we might as well ask, what are its 'jazz moments', or what is the amount of "jazzness" in a particular moment of the album. The concept of "jazzness", suggested by Gridley et al. (1989), determines that in "Sister Moon", for example, we may find several jazz elements, such as improvisation, some instrumentation, the rhythmic patterns, the harmony, the openness of the structure, the different dynamics and tension degrees in the performance. But the question remains: are these elements enough to categorize this piece as a jazz performance?

On the other hand, the reasons that might lead to the acceptance of River: The Joni Letters as a jazz album don't reside solely in the musical realm. The musicians in this album may be playing jazz, but it is important to note that the repertoire is not endemic to jazz, just like in the case of most of the guest singers. However, the choice of Joni Mitchell's music may represent an element of prestige, as this artist is looked upon by the critics as a 'high art song' persona. As for the singers' choice, except for Tina Turner, the remaining artists inhabit a pop musical sector that is, in cultural and interpretative terms, closer to jazz or to the same 'high art song' milieu as Mitchell's.

The inherent complexity and contradictions in the attempts of defining jazz, with its constant changes and reinventions, lead Ake et al. (2012) to the assertion that jazz doesn't possess any essential features. According to these authors:

Some jazz performances swing; others feature a different groove or no groove at all. Some jazz highlights improvisation; some of it is meticulously planned in advance. . . . Some jazz adopts an unflinchingly "important" and anticommercial stance; much of it openly courts the marketplace or invites us simply to have a good time. Some musicians possess a strong moral compass and toil to build a more just society; others are self-centered louts (Ake et al., 2012, p. 5).

Neotraditionalists certainly don't agree with this idea, but it allows us to con- sider jazz as something in permanent mutation. Despite some resistance, Herbie Hancock demonstrates in these albums that the possibilities are there, waiting to be explored.

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