Mike Daley - essay - Black English and rap music: a comparison

"You hear me when I moan": timbre and style in the singing of Robert Johnson1
Mike Daley York University

Through the popularity and influence of only 29 songs (41 performances in total including alternate takes), Robert Johnson has come to be seen as one of the most important, and certainly the most famous, of the Delta bluesmen. One of the most striking qualities of the handful of recordings which comprise Robert Johnson's output is the great variety of sounds and styles emanating from a single performer with an acoustic guitar. In this paper, I will examine some aspects of Johnson's voice and vocal style as documented in these 41 recordings, waxed between November 23, 1936 and June 20, 19372 .
The study of vocal style has little in the way of precedent. This is probably due to the necessary emphasis on timbre, which is still the most woefully underdeveloped area of musical analysis. Despite acknowledgments of the sorry state of timbre research in much of the literature, actual work is hard to find. Some examples which have guided me in my own work are Robert Cogan's New Images of Musical Sound(1984), which uses a spectrographic approach, and Alan Lomax's Cantometrics project (1968), which, though heavily criticized in its time, remains one of the only studies to systematically identify and classify voice qualities. I worked out a few methods in my master's thesis, "'One who sings with his tongue on fire': Change, continuity and meaning in Bob Dylan's vocal style, 1960-66" (Daley 1997), some of which will be applied here, and I will attempt to establish some new approaches in the present work.

Robert Johnson's vocal performances alone could easily warrant a book-length study. In the interests of relative brevity, then, I will largely confine my commentary to the timbral aspects of his work, with reference to melodic considerations where they impact on timbral choices. I use a series of verbal descriptors to classify gross voice types in Johnson's work, and cross-reference the uses of these voice types to other musical and textual (in the sense of lyric text) parameters. That, in a nutshell, is the substance of my analysis here. I am working with the hypothesis that Robert Johnson's varied vocal sounds and techniques are not random, but can be seen as parts of a reasonably systematic and coherent expressive system. In this way, I am taking a microcosmic approach to Delta blues in general by positing that the whole can only begin to be understood through the close reading of specific artifacts.

I have employed here a series of informal verbal descriptors to identify various general "voices" used by Johnson throughout the 41 performances. Some songs employ a single "voice" virtually unchanged throughout, while others will cycle through two or more "voices", often with the change dependent on phrase positions. In addition to specific "voices", I have also tracked the keys, melodic ranges, lyric themes, and melodic "blues family" according to the typology developed by Jeff Todd Titon in his pioneering Early Downhome Blues(1982). Though this data does exist in a computerized spreadsheet form, I have demurred here from employing the types of mathematical machinations used to detect patterns in Lomax's Cantometrics and in my thesis on Bob Dylan's vocal style. I believe that the sample used here is sufficiently small to permit (unlike those two very large projects), and would be ultimately better served, through an impressionistic, "manual" approach to comparison.

I have also noted the ranges of Johnson's performances in terms of scale degrees, rather than semitones. This allows for the use of concepts such as the tenth, which will have more meaning to the musically trained reader than "17 semitones".

It has been noted about blues lyrics that, rather than conforming to a narrative like Euro-American ballads, verses are drawn from a pool of circulating stanzas and assembled anew for each song without regard to narrative thread or thematic unity. In spite of this, Robert Johnson's lyrics tend to each convey a fairly cohesive theme, even as they employ the blues technique of combining verses from the "public domain". Scott Ainslie comments in his book (co-authored with Dave Whitehill) of Robert Johnson transcriptions about "When You Got A Good Friend": "Like almost all of Johnson's tunes, it is thematically much tighter than the bulk of the Delta blues that had been recorded previously" (Ainslie and Whitehill 1992:24). In my endeavour to classify these lyric themes, I have been inspired by Matt Vanderwoude's survey of blues lyric classification schemes in his master's thesis on the early work of Muddy Waters (Vanderwoude 19 ). These schemes tend to be quite general, as is necessitated by the great breadth of blues lyrics. Again, though, with such a small sample of unique lyrics (29 in all), I have chosen to develop a new scheme specifically with Johnson's songs in mind3.

1 romantic dissatisfaction (including loneliness)
2 travel
3 metaphorical sexuality (including the use of euphemisms for genitalia)
4 violence
5 humor/hokum
6 occult/evil
7 the blues themselves
8 alcohol

The centerpiece of my analytical schema for Robert Johnson is the description of his various "voice types". There are four general voice types in my system, along with a set of "rules" that apply to situations where timbral variation occurs.

Voice types:

1. "singing"
-sharply articulated consonants
-resonant "chest voice"
-slightly nasal due to a closed supraglottis (upper throat).
-usually with a slight vibrato

2. "kissing"
-lips extruded
-emphasizes the "oo" vowel sound (the "oo" vowel has some of the lowest formants of all the vowels - Johnson's use of the "kissing" sound tends to lower the formants of other vowels as well)
-reduced tongue movement and thus duller articulation of consonants (which in turn makes Johnson's delivery slurred and lyrics harder to decipher)
-has the acoustic effect of increasing upper midrange frequencies in the voice, which in turn aids in projection (see Ry Cooder's speculations on Johnson's use of the acoustic principle of "corner loading" during his hotel room recording sessions, Cooder 1990)
-sometimes predominant in a song, sometimes used for timbral contrast

3. "speaking"
-lips spread
-smoother timbral quality
-reduced articulation of consonants
-elimination of vibrato
-used for spoken passages and special situations
-some accentuation of lower formants - a "deeper" timbral quality

4. "harsh/narrow"
-closed supraglottis - nasal sound
-lateral pressure on the vocal cords causes harsh, noisy voice quality
-used sparingly except in the special humourous situation of "They're Red Hot"

Rules of timbral variation:

1. Johnson tends to efface the timbral differences between vowels in certain passages, particularly those where low formants are more prevalent.

2. Johnson tends to hold nasal consonants when they have the final position in a phrase, and he tends to "close" and darken vowels when they are held in the final position. This often occurs at the ends of the antecedent sub-phrase in the A and B lines of three-line stanzas.

3. In three line stanzas, Johnson tends to vary line C in timbre.

4. Johnson tends to vary bridge sections in timbre.

5. Generally, Johnson uses more timbral variations in lyrics that are particularly derivative or repetitious.

With this scheme in mind, what follows is a take-by-take breakdown of Johnson's performances, in chronological order4 .

"Kindhearted Woman Blues"
recorded November 23, 1936.
key: B
range: a tenth
theme: romantic dissatisfaction
blues family: 4

Two takes exist of this song. Generally, the "singing" voice is used. The first take is a good example of the second rule, as Johnson holds the final note of phrases in a nasal consonant or a closed vowel. In this line, Johnson holds the nasal consonant [n] (in "women") as well as the final vowel [i] (in "be"), "darkening" the vowel by closing his mouth slightly.

but these evil-hearted women, man they will not let me be listen

There is quite a bit of timbral variation in the bridge of this song. Johnson affects a narrow timbre for the first line, switching to the "kissing" voice for the first half of the second line, then back to an opening singing voice for the remainder of the second line and the third and fourth lines. This variation might be connected to the prevalence of certain vowel sounds in these lines. The first line contains a preponderance of high formant vowels, namely [a] ("ain't", "makes") and [I] ("thing", "drink"), which lend to a certain nasality. Johnson seems to respond to this by rendering the entire line more nasal. That is, he may have desired a variation in timbre because of the structural position of this line (the first line in the contrasting bridge section of the song), and used the timbral profile of the prominent vowels (they are prominent largely because they are rhymed) to suggest which "voice" to use.

A-ain't but the one thing - makes Mr. Johnson drink
I's worried 'bout how you treat me baby - I begin to think:
Oh, babe - my life don't feel the same
You breaks my heart when you call Mr. So-and-So's name listen

A similar explanation can be given for his use of the "kissing" voice in the first half of the second line. This section contains a number of low formant vowels - [ou] ("worried", Johnson's pronunciation of "you") and [ow] ("bout", "how"), which work well for that voice type. In fact, when these vowels cease to be used, with the word "treat" in the second line, so does the "kissing" voice. The change back to a "singing" voice is precipitated by Johnson's use of falsetto throughout the third line - he breaks out of the "kissing" voice in the second half of the second line as if to prepare for the falsetto, a vocal technique which requires "singing" production.

The timbral variation displayed in the first take of "Kindhearted Woman Blues" is virtually duplicated in the second take, even as other details change (slight alteration of lyrics, the replacement of the guitar break with an extra verse).

"I Believe I'll Dust My Broom"
recorded November 23, 1936
key: E
range: a tenth
theme: romantic dissatisfaction
blues family: 1

Apart from Johnson's use of timbral variation corresponding to the second rule, this is fairly uniformly sung in the "singing" voice. The held nasals and closed final vowels are conspicuous in the third and sixth stanzas. In the third, the word "woman" is sung in such a way that the [n] nasal consonant is prolonged, while the [e] directly preceding is almost imperceptible. In the sixth stanza, the final vowel of ñChinaî is closed to the point that it begins to sound like a nasal consonant.

I don't want no woman - wants every downtown man she meet listen
I'm 'on call up China - see is my good girl over there listen

"Sweet Home Chicago"
recorded November 23, 1936
key: F#
range: a tenth
theme: travel
blues family: 2

One of the most interesting aspects of "Sweet Home Chicago" vocally is Johnson's variations on the syllable "oh" throughout the first and second stanzas. His pronunciations vary from [o] to [ou] to [ow], with every point in between. Here, edited together are all four occurrences of the syllable:

"Oh" listen

"Sweet Home Chicago" marks the first appearance on record of Johnson's "speaking" timbre. Most noticeably, it can be heard in the second lines of the third, fourth and fifth stanzas. Here is an example from the third stanza:

Now one and one is two - two and two is four,
I'm heavy loaded baby - I'm booked, I got to go
Cryin' baby - honey, don't you want to go?
Back to the land of California, to my sweet home Chicago. listen

Apart from this, Johnson's performance is notable for the unusual pronunciation of "California" in the song's refrain ("Californoo"). He extrudes his lips for this word, perhaps giving a preview of the "kissing" voice, which appears more prominently in the word "Chicago", the last word of each verse. It's unclear why Johnson would choose to use the "kissing" voice for the two place names in the song (Ainslie and Whitehill, presumably following Stephen LaVere in the Robert Johnson: The Complete Recordings liner notes transcribe the last verse as containing a reference to Des Moines, Iowa; I have serious reservations about this).

"Ramblin' On My Mind"
recorded November 23, 1936
key: F#
range: a tenth
theme: travel
blues family: 1

For the most part, "Ramblin' On My Mind" features the "singing" timbre, albeit in a rather high tessitura. The two takes of this song have somewhat different lyric texts, and in the second take, Johnson introduces a harsh timbre on the word "believe". This might be connected to the high brightness of the [i] vowel as well as the high pitch of the note itself. Probably these two factors along with an wish to give the word emphasis account for this rather isolated occurrence of vocal rasp.

I believe - I believe my time ain't long
I believe - I believe that my time ain't long
But I'm leaving this morning
I believe I will go back home listen

"When You Got A Good Friend"
recorded November 23, 1936
key: F#
range: a tenth
theme: romantic dissatisfaction
blues family: 1

This song shares an number of musical parameters with "Ramblin' On My Mind", and accordingly it shares some common details of vocal performance. Like the earlier song, "When You Got A Good Friend" is in F#, with a similar range and melodic type and thus many tones in common. And, like "Ramblin' On My Mind", this song contains some occasional vocal rasp, on the high third scale degree and on an [i] vowel. In this case, the rasp falls on the word "sweet" in the third stanza (in the second take only - in the first take the word is thrown away too quickly for rasp to be audible).

She's a brownskin woman - just as sweet as a girlfriend can be listen

This song also has pronounced and sustained nasal consonants in the terminal positions of phrases. The [n] sound is particularly common here.

"Come On In My Kitchen"
recorded November 23, 1936
key: B
range: an octave
theme: romantic dissatisfaction
blues family: n/a (the form does not conform to Titon's model)

Probably the most striking aspect of this performance is the prolonged use of the "kissing" timbre. Sometimes Johnson extrudes his lips so much as to be almost unintelligible. An explanation for the use of this timbre might be found in the occurrences of [o], [oo] and [ow] sounds in the refrain.

You better come on in my kitchen
babe, it's goin' to be rainin' outdoors listen

Johnson seems to take this as a cue to use the "kissing" timbre throughout the song, and to generally vary timbre as well. Even this refrain contains more nasal syllables, on the initial "you" and later on "in". The antecedent first phrase of the line is more in the "singing" voice than the second. Johnson continues to switch between more and less "kissing" timbres throughout the performance, including a spoken passage in the fourth stanza which is, predictably, performed in the "speaking" timbre.
The use of the "kissing" timbre is less pronounced in the second take.

"Terraplane Blues"
recorded November 23, 1936
key: B
range: a fifteenth
theme: metaphorical sexuality
blues family: 2

This is one of Robert Johnson's most stirring performances on record, with an active guitar accompaniment and a vocal performance full of surprising melodic turns and falsetto whoops. For the most part, he uses the regular singing timbre, with characteristic held nasals at the ends of some lines.

"Phonograph Blues"
recorded November 23, 1936
key: B
range: a fifteenth
theme: metaphorical sexuality
blues family: 4

This is an example where the two takes of a Johnson song differ radically, and must be discussed separately. The first take might be compared in sound and style to "Kindhearted Woman Blues", with which it shares its key and melodic type. This take contains a fair bit of timbral interest. In the second stanza, Johnson interposes the "kissing" timbre into the third line (it is his general tendency to vary the third line of three-line stanzas where variation occurs). The third stanza, which functions as a kind of bridge (by virtue of its contrasting stanzaic/melodic form and stop-time guitar accompaniment) features quite a bit of timbral variation from line to line. The different "voices" are mapped out below:

Now, we played it on the sofa, now [singing]
we played it 'side the wall [speaking (though the line is sung)]
My needles have got rusty, baby [speaking]
they will not play at all [speaking]
We played it on the sofa [kissing]
and we played it 'side the wall [singing]
But my needles have got rusty [kissing]
and it will not play at all [singing] listen

The second take is much more similar to "I Believe I'll Dust My Broom" in terms of melodic style and especially in terms of guitar accompaniment. Likewise, this take has none of the timbral variation of the first take, and is performed entirely in a rather strident "singing" timbre.

"32-20 Blues"
recorded November 26, 1936
key: A
range: a twelfth
theme: violence
blues family: 1

For the most part, Johnson affects an uncharacteristically deep "singing" voice throughout this song, except for two stanzas, both of which begin with the well-worn line "Ah-oh, baby where you stay last night". Johnson slightly contracts his supraglottis at these points, creating a smaller, less resonant sound. These stanzas also mark a variation in the guitar accompaniment, so it is likely that Johnson used these timbral changes as structural variations, rather than in connection to some preponderance of a vowel sound or textual meaning.

"They're Red Hot"
recorded November 30, 1936
key: C
range: a tenth
theme: humour/hokum
blues family: n/a (not a blues song)

This song is a rather singular one in Johnson's output. In addition to bearing almost no relation to his other songs in musical and lyric style, his voice is almost unrecognizable. Johnson sings almost the entire song in an affected nasal rasp, presumably for humourous effect given the type of lyrics he is singing. Only on occasion does he let this vocal conceit slip, and usually for brief spoken passages.

Hot tamales and they red hot
yes, she got 'em for sale
Hot tamales and they red hot
yes, she got 'em for sale
I got a letter from a girl in the room
Now, she got somethin' good she got to bring home soon, now
It's hot tamales and they red hot
yeah, she got 'em for sale, I mean
Yes, she got 'em for sale, yeah listen

"Dead Shrimp Blues"
recorded November 30, 1936
key: B
range: a fifteenth
theme: metaphorical sexuality
blues family: 4

This song is not unlike many of Johnson's performances, with his by now trademark held nasals at the ends of line. In the "bridge" stanza (Stanza 3) he varies his timbre significantly, using a change in voice quality to mark the halfway point division within the stanza. This technique is strongly reminiscent of Johnson's performance in the first take of "Phonograph Blues" (see above), which is, interestingly, based on a similar lyric theme and shares both key and melodic family with "Dead Shrimp Blues".

Everything I do, babe, you got your mouth stuck out (speaking)
Hole where I used to fish, you got me posted out (speaking)
Everything I do, you got your mouth stuck out (singing)
At the hole where I used to fish, baby (singing)
You've got me posted out (singing) listen

"Cross Road Blues"
recorded November 30, 1936
key: B
range: a twelfth
theme: occult/evil
blues family: 4

"Cross Road Blues" is a performance that features Johnson's "singing" voice pushed to its limit. At several points throughout the two takes of this song, Johnson slips into a rasp, probably caused by the tremendous sound pressure generated by Johnson's larynx. Even with such a careening, forceful performance, though, Johnson manages to slip some timbre variation into the final stanza of the first take.

And I went to the crossroad, mama (singing)
I looked east and west (singing)
I went to the crossroad, baby (kissing)
I looked east and west (kissing)
Lord, I didn't have no sweet woman (singing)
ooh-well, babe, in my distress (speaking) listen

"Walking Blues"
recorded November 30, 1936
key: B
range: an octave
theme: travel (?)
blues family: 1

This is probably the Johnson performance with the most timbral variation overall. The variation also seems more random than in other songs. This might be explained by the relative monotony of the lyric text (basically two repeated couplets per stanza). He might have felt the urge to 'spice up' the performance somewhat. The entire performance is full of unusual and copious variation, but a look at the first stanza should suffice to make the point:

I woke up (rasp) this mornin' (singing)
feelin' round for my (singing)
shoes...Know 'bout I got these (kissing)
old walkin' blues, woke (singing, with rasp)
Up this mornin' feelin' 'round, (singing)
oh, for my shoes (kissing)
But you know 'bout 'at I got these old walkin' blues (singing) listen

These variations are not seemingly connected to textual meaning; in fact, they cross over syntactical divisions quite easily. This suggests that Johnson was indulging in more "playful voicedness" than the conscious, rather systematic timbral variation of some of his other performances.

"Last Fair Deal Gone Down"
recorded November 30, 1936
key: A
range: a twelfth
theme: travel (?)
blues family: n/a (does not follow the three-line blues form)

Johnson's performance here exemplifies his practice of varying timbre from line to line or stanza to stanza when the lyric is particularly repetitious or derivative of other blues lyrics. He varies mildly between a regular "singing" timbre and more raspy, narrow vocal sounds, some of which recall the parodic flavour of "They're Red Hot":

My captain's so mean on me (raspy, narrow)
My captain's so mean on me (singing)
My captain's so mean on me, good Lord (raspy, singing)
On this Gulfport Island Road (singing) listen

"Preaching Blues (Up Jumped the Devil)"
recorded November 30, 1936
key: E
range: a tenth
theme: the blues themselves
blues family: 1

The use of the narrow, raspy timbre so prevalent in "They're Red Hot" can be generally linked to the November 30, 1936 session. It occurs in a few guises; in the present example, it is used as a timbre variation for the third line in the first stanza:

Mmmmmmm mmmmmm (all lines except the last one are in the "singing" timbre)
I's up this mornin'
ah, blues walkin' like a man
I's up this mornin'
ah, blues walkin' like a man
Worried blues,
give me your right hand (narrow, raspy) listen

In the fifth and final stanza, Johnson ventures a similar type of variation, though he substitutes the "kissing" timbre for the narrow, raspy one on the third line.

I been stutterin' (all lines except the last one are in the "singing" timbre)
oh, oh, drive, oh, oh, drive my blues
I been stutterin' and
I'm 'on drive my blues away
Goin' to the 'stil'ry
stay out there all day (kissing) listen

"If I Had Possession Over Judgement Day"
recorded November 30, 1936
key: A
range: a ninth
theme: romantic dissatisfaction
blues family: 3

This performance continues the pattern noted above of varying timbre on the third line of the three-line stanza. Rather than using the "singing" voice as the rule, though, Johnson uses a modified5 speaking timbre. For variation, he uses the singing voice, with its more nasal, strident quality.

And I went to the mountain (all lines except the last one are in the "speaking" timbre)
lookin' far as my eyes could see
And I went to the mountain
lookin' far as my eye would see
Some other man got my woman and the '-a (singing)
lonesome blues got me (singing) listen

"Stones In My Passway"
recorded June 19, 1937
key: A
range: a fourteenth
theme: travel
blues family: 3

"I'm A Steady Rollin' Man"
recorded June 19, 1937
key: Bb
range: a thirteenth
theme: travel
blues family: 4

"From Four Till Late"
recorded June 19, 1937
key: C
range: a tenth
theme: romantic dissatisfaction
blues family: 3

Johnson uses an unchanging "singing" voice throughout these performances. There is almost no rasp at all, which is probably due to the moderate tessituras of these songs.

"Hellhound on my Trail"
recorded June 20, 1937
key: E
range: an eleventh
theme: travel (?)
blues family: 1

"Hellhound on my Trail" features a particularly penetrating and tremulous variant of the "singing" voice. This performance is a breed apart from the previous three of the day's session, and this partly accounts for the song's legendary status in Johnson's oeuvre.

"Little Queen of Spades"
recorded June 20, 1937
key: A
range: a fifteenth
theme: metaphorical sexuality
blues family: 4

This performance is substantially similar to "Kindhearted Woman Blues" and its variants. The guitar accompaniment is almost identical, as is the vocal style (which is in the "singing" voice), though this song lacks a bridge section, and thus the timbral variation that would accompany it (see "Kindhearted Woman Blues" and "Phonograph Blues (take 1)" above).

"Malted Milk"
recorded June 20, 1937
key: Eb
range: an octave
theme: alcohol
blues family: 3

"Drunken Hearted Man"
recorded June 20, 1937
key: Eb
range: an octave
theme: alcohol
blues family: 4

Among many other similarities, these two songs (three performances in all) share the use of "speaking" vocal timbre throughout. This seems to suit the bathetic texts and wistful melodies of these songs.

(from take 1)
I been dogged and I been driven
ever since I left my mother's home
I been dogged and I been driven
ever since I left my mother's home
And I can't see the reason why
that I can't leave these no-good womens alone listen

"Me and the Devil Blues"
recorded June 20, 1937
key: Bb
range: a fifteenth
theme: occult/evil
blues family: 4

Like the other song here that I have classified as being in the "occult/evil" theme ("Cross Road Blues"), this performance has a very even, regular use of the "singing" vocal timbre. One might expect Johnson to give these dark, disturbing texts a more dramatic treatment, but he seems to reserve his most varied performances for those songs with more repetitive and derivative texts, like "Walking Blues" and "Last Fair Deal Gone Down".

"Stop Breakin' Down Blues"
recorded June 20, 1937
key: A
range: a seventeenth
theme: romantic dissatisfaction
blues family: n/a (does not follow three-line blues form)

"Travelling Riverside Blues"
recorded June 20, 1937
key: Bb
range: a twelfth
theme: travel
blues family: 3

Both of these songs (with two takes of "Stop Breakin' Down Blues") feature an unchanging "singing" timbre.

"Honeymoon Blues"
recorded June 20, 1937
key: B
range: a fifteenth
theme: romantic dissatisfaction
blues family: 3

This is one of the few performances from the June 20, 1937 session that features any timbral variation at all. What variation exists is slight - Johnson introduces a "kissing" timbre into the third line of the second stanza in what is generally a "singing" vocal performance.

"Love In Vain"
recorded June 20, 1937
key: A
range: a tenth
theme: romantic dissatisfaction
blues family: 3

This beautiful song is performed entirely in the "singing" voice. It is interesting, though, to compare the final stanzas of the two existing takes, Take 1 and Take 4. Both stanzas are composed almost completely of vocables, with the first take centering on phonetic variations of the [o] vowel:

Ou hou ou ou ou
hoo, Willie Mae
Oh oh oh oh oh hey
hoo, Willie Mae
Ou ou ou ou ou ou
hee vee oh woe
All my love's in vain listen

In the fourth take, Johnson has switched to vocables related to the [e] and [a] vowel sounds:

Eee eee eee eee ooo
hoo, Willie Mae
Ey ey ey ey ey ey ey
hoo, Willie Mae
hee vee oh woe
All my love's in vain listen

Such vocal extemporization is rare in Johnson's recorded output, just as he was seemingly modest about his guitar playing abilities6.

"Milkcow's Calf Blues"
recorded June 20, 1937
key: Bb
range: a seventeenth
theme: metaphorical sexuality
blues family: 2

This song is substantially similar to "Terraplane Blues", and it shares that song's reliance on a "singing" timbre with the usual held nasals at the ends of certain lines.

Conclusions

In reference to my goal of correlating Robert Johnson's vocal performances to other aspects of his repertory, I will make a few possible connections here. Any generalizations that I might formulate here must be tempered with a major extenuating factor: Johnson's body of work, though it is all we have, is far too small to produce statistically significant results. Thus any references to a cohesive expressive system are even more speculative than is usual in this type of work.

spreadsheet image

Looking at the distribution of various parameters (enumerated above) over the five recording dates in chronological order, what immediately jumps out is the fact that lyric themes are often grouped in twos, especially throughout the November 23, 1936 session. Other than that, it can be said that Johnson varied his themes more in later sessions than in that first session.
If the songs are grouped by theme, it can be seen that the amount of timbre variation is more or less equally distributed over the 29 songs, though there is more variety in the general voice types within the "romantic dissatisfaction" theme. The "metaphorical sexuality" songs tend to have the widest ranges, all of them wider than a fifteenth. The "alcohol" songs have identical general voice types, "speaking", and identical ranges and keys as well. And the single humour/hokum song, "They're Red Hot", has a voice type all its own, the "harsh/narrow" voice.

Though the sample is small, the amount of theme to voice type correlation suggests that Johnson's use of vocal timbres is not random. As noted above, the amount of timbral variation within a song also seems to be connected to the degree of repetition in a lyric or how derivative and cliched it is. There does not appear to be significant correlations between vocal timbre and other parameters beyond this.

Mike Daley - essay - Black English and rap music: a comparison