Beats and Bars:
A Journey Through Hip-Hop’s Identity

Born in the Bronx during the 1970s, hip hop has grown into a worldwide cultural movement, shaping music, language, fashion, and activism (Hip Hop: A Culture of Vision and Voice) . Its adaptability has led to the emergence of distinct subgenres, each reflecting unique regional styles, sounds, and narratives. From the hard-hitting beats of Gangsta Rap to the melodic hooks of Trap, hip hop continues to evolve while preserving its creative essence. In this project, we explore hip hop's subgenres through three key aspects:

Influence and Popularity Over Time: Charting the rise and evolution of subgenres across decades.
Musical Qualities: Examining rhythm, tempo, and melody that define each subgenre's sound.
Lyrical Themes & Language: Highlighting recurring topics and language that give each style its voice.

Chapter I: Trends

This chapter analyzes overarching trends across three key dimensions of hip-hop and rap: popularity, melody, and lyrics. By analyzing changes over time, Chapter 1 provides a view of how the genre has evolved and diversified.

1.1 Popularity Trends

This visualization explores hip-hop’s evolution from the 1970s to the 2010s, highlighting the growth and popularity of its subgenres. The upper area graph shows song popularity through views, while the lower line graph tracks the number of songs released in each subgenre over time, with peak years marked for key styles.

In the earlier decades, Trap wasn’t as prominent, in correspondence to hip-hop still carving out its space in the music industry. As hip-hop gained widespread recognition and became more mainstream in the 2000s and 2010s, Trap emerged as one of its most influential and defining subgenres.

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The peak year for the Trap subgenre was 2017, with 1,168 songs released. This signifies not just a peak in output but highlights the sheer prominence of Trap within the hip-hop landscape during that year.

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In terms of views, Trap songs collectively amassed over 242 million views in 2017, underscoring its popularity not only in production but also in listener engagement.

1.2 Melody Trends

This visualization presents trends over time in four key metrics for songs across subgenres: Duration, BPM, Pitch, and Volume. The graph includes individual data points for songs, and the red trend lines indicate overall changes in these metrics from 1991 to 2018. Songs are plotted by year and the white line represents the average value of the year, with the red line indicating the overall trends. This graph captures both subgenre-specific fluctuations and broader patterns in the evolution of hip-hop's sound.

Duration: Trap songs have maintained relatively stable durations, reflecting consistency in structure while other elements of the subgenre have evolved.

Pitch: Trap music’s pitch remains steady, supporting its signature deep basslines and atmospheric layers without major shifts over time.

Volume: The volume of Trap music has shown a consistent increase over time, indicating a trend toward louder, more impactful production styles.

You can further explore with the visualization by highlighting different genres to see how specific sub genres change over time and compare that with the general trend.

1.3 Lyrical Trends

The visualization, Word Category Trend, shows the rank of frequency for various word categories over three decades (1980-2000, 2000-2010, 2010-2020). Categories such as "relationships," "violence," and "time" have fluctuated in popularity, with "relationships" consistently ranking higher in lyrical focus.. Each category is represented as a unique shape and the connecting lines illustrate trends over time. The chart highlights how word categories such as relationships, violence, time, wealth, and emotion have shifted in prominence within hip-hop lyrics. You can click on individual datapoint (icon) for details about that word category in a specific decade, or click on the connecting lines to highlight the whole trend of a word category.

The second visualization, Unique Word Count Trend, tracks the number of unique words used in songs over time. This chart visualizes the unique word count in hip-hop lyrics over time, with each data point representing a single song. The x-axis shows the release year of the songs, while the y-axis displays the number of unique words in each song. A general decline in unique word count is observed, suggesting a trend toward more repetitive or standardized lyrics across all subgenres.

The decline in unique word count is slightly more pronounced in trap music compared to other subgenres. This highlights a shift in lyrical diversity over time, with trap increasingly focusing on repeated phrases or consistent themes.

Chapter II: Features

This chapter presents the foundational elements of hip-hop music by analyzing melodic and lyrical trends. It explores melodic features such as BPM, pitch, and volume, showcasing how these elements shape the soundscapes of different subgenres. The lyrical analysis focuses on word usage, unique word count, and category trends, illustrating shifts in thematic focus and lyrical complexity over time. By combining these melodic and lyrical insights, Chapter 2 highlights the relationship between musical composition and storytelling– how these elements shape the identity and expression of the genre over time.

2.1 Melodic Features: BPM

This dashboard explores the tempo characteristics of hip-hop subgenres, specifically focusing on beats per minute (BPM). It consists of three primary visualizations:

Average BPM: A line graph showcasing the average BPM for each subgenre, differentiated by musical type (Vocal or Background Music).

Detail BPM: A detailed slope chart of individual songs' BPM values per subgenre, connected by musical type, emphasizing distribution and variability.

BPM Distribution: Histograms representing the distribution of BPM values for each subgenre, separated into Vocal and Background Music.

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  • Most subgenres have higher BPM in Background Music than Vocals, except for drill and emo rap.
  • Trap has the highest average BPM for Vocals while Boom Amp has the lowest average BPM
  • Trap music's average BPM stands at 123.77 for Background Music (BGM) and 133.16 for Vocals. This positions Trap as a moderately fast-paced subgenre compared to others, maintaining energy while accommodating its signature layered rhythms and hi-hat rolls.
  • The distinction between BGM and Vocal tracks highlights how Trap uses tempo to create contrasting dynamics within its productions.
BPM Parity Between BGM and Vocal:

Almost half of the songs in Trap show similar BPM for their BGM and Vocal components. This highlights a significant proportion of tracks where the vocal rhythm is tightly synchronized with the instrumental beat.

Higher Vocal BPM in Many Tracks:

For approximately half of the remaining tracks, the vocal BPM surpasses the BGM BPM. This suggests that in these songs, vocal delivery is faster-paced, which could reflect the influence of double-time flows or rapid-fire lyrical styles, a common feature in Trap music.

2.2 Melodic Features: Pitch and Volume

In this visualization, we compare the pitch and volume of BGM and vocals across various subgenres. The right graph displays data points for all songs, using a kernel density plot to illustrate the distribution. The left graph aggregates the data by subgenre, showing an overview of pitch and volume trends. Additionally, we performed regression analysis to examine the correlation between pitch and volume for each subgenre. The width of the connecting lines represents the subgenre's popularity, measured by average views. Users can highlight different subgenres to gain more detailed insights.

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Freestyle as an Outlier

The peak year for the Trap subgenre was 2017, with 1,168 songs released. This signifies not just a peak in output but highlights the sheer prominence of Trap within the hip-hop landscape during that year.

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Drill Has the most Distinct Difference between Vocals and BGM

In terms of views, Trap songs collectively amassed over 242 million views in 2017, underscoring its popularity not only in production but also in listener engagement.

2.3 Lyrics by Sub Genre

The table and radar charts together provide a view of how lyrical themes vary across subgenres. The table highlights the top and bottom 3 rankings for themes such as relationships, violence, spirituality, and wealth, with each column representing a thematic category and rows displaying the highest-ranking subgenres. For instance, Trap leads in slang and substance, while East Coast dominates appearance and wealth. Complementing this, the radar charts visually compare the thematic focus of each subgenre, emphasizing distinct content areas like wealth, relationships, and emotion. By juxtaposing each subgenre with Trap, the charts offer a clearer understanding of thematic diversity and cultural influence within the lyrical content of these styles.

This radar chart metric visualizes the relative emphasis on lyrical categories across various hip-hop genres. Each axis represents a thematic category (e.g., wealth, violence, emotion), while the distance from the center indicates the percentage of words in that category relative to the total categorized words for the genre.

Axes Represent Themes: Each axis corresponds to a specific lyrical theme, such as "emotion," "wealth," or "violence."

Distance from Center: The farther a point is from the center, the higher the percentage of words associated with that theme, meaning the genre places more emphasis on it.

Normalized Metrics: The percentage calculation ensures normalization, allowing direct comparisons across genres regardless of their overall word counts. This metric reflects relative importance rather than raw frequency.

Boom Bap

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Conscious Hip Hop

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Dirty South

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Drill

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East Coast

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Emo Rap

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Freestyle

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Gangsta Rap

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Hardcore Hip Hop

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West Coast

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  • Boom Bag: Most subgenres have higher BPM in Background Music than Vocals, except for drill and emo rap.
  • Gangsta Rap: Trap has the highest average BPM for Vocals while Boom Amp has the lowest average BPM
  • Conscious Hip Hop: Trap music's average BPM stands at 123.77 for Background Music (BGM) and 133.16 for Vocals. This positions Trap as a moderately fast-paced subgenre compared to others, maintaining energy while accommodating its signature layered rhythms and hi-hat rolls.
  • Drill: The distinction between BGM and Vocal tracks highlights how Trap uses tempo to create contrasting dynamics within its productions.
  • Freestyle: Trap and Freestyle share similar emphasis on slang, reflecting the improvisational and laid-back nature of both styles

Chapter III: Songs

This chapter analyzes the lyrical sentiment and melodic attributes including pitch and volume. Analyzing sentiment visualizes the emotional journey within each song, capturing shifts between positivity, negativity, and neutrality between the verses. On the melodic side, pitch and volume visualizations highlight the tonal and dynamic layers that define hip-hop’s soundscape. Together, these analyses illustrate the emotional and auditory diversity that shapes the storytelling and energy of hip-hop music.

Click on the sub genre tabs below to explore how each song compares in sentiment and melody to other songs of the same sub genre.

3.1 Lyrical Sentiment

This sentiment barcode chart provides a detailed visualization of the sentiment trajectory within each song. Each bar corresponds to a lyric line, with color-coded sentiment scores ranging from -1 (blue, negative) to 1 (orange, positive). The horizontal arrangement represents the sequence of lyrics, forming a barcode for each song.

Individual Bars: Each bar represents a single lyric line, its color reflecting the sentiment score.

Barcodes for Songs: The entire horizontal barcode signifies the sentiment distribution throughout a single song's lyrics.

Color Gradient: Shades range from red for strongly negative sentiments, through white for neutral lines, to blue for highly positive sentiments.

You can click on each individual barcode to see the overall sentiment score of a song or click on each stick to see a verse and its sentiment score.

3.2 Pitch and Volume

We conducted a frame-by-frame analysis of pitch and volume for the top 10 songs in each subgenre, visualizing each song on a pixel display with the horizontal axis representing time. Each song features two tracks: the upper track for BGM and the lower track for vocals.

Similarities Among Top Songs: There are notable similarities among the top songs, particularly in their BGM. These include periodic high-frequency pitches and a generally fast tempo with higher volume levels. In contrast, vocals tend to dominate the higher frequencies but exhibit relatively lower volumes. While further insights could be drawn from direct comparisons between specific songs, we do not delve deeper here.

Differences in Time-Frequency Characteristics Across Subgenres: In addition to similarities, distinct differences in time-frequency characteristics can be observed across subgenres. For instance, the frequency of high-pitched sounds in the BGM of Boom Amp is significantly lower compared to Trap. This highlights Trap as a genre characterized by faster tempos and more frequent intermittent high-frequency sounds, distinguishing it from other subgenres.

3.2 Pitch and Volume

We conducted a frame-by-frame analysis of pitch and volume for the top 10 songs in each subgenre, visualizing each song on a pixel display with the horizontal axis representing time. Each song features two tracks: the upper track for BGM and the lower track for vocals.

Similarities Among Top Songs: There are notable similarities among the top songs, particularly in their BGM. These include periodic high-frequency pitches and a generally fast tempo with higher volume levels. In contrast, vocals tend to dominate the higher frequencies but exhibit relatively lower volumes. While further insights could be drawn from direct comparisons between specific songs, we do not delve deeper here.

Differences in Time-Frequency Characteristics Across Subgenres: In addition to similarities, distinct differences in time-frequency characteristics can be observed across subgenres. For instance, the frequency of high-pitched sounds in the BGM of Boom Amp is significantly lower compared to Trap. This highlights Trap as a genre characterized by faster tempos and more frequent intermittent high-frequency sounds, distinguishing it from other subgenres.

3.2 Pitch and Volume

We conducted a frame-by-frame analysis of pitch and volume for the top 10 songs in each subgenre, visualizing each song on a pixel display with the horizontal axis representing time. Each song features two tracks: the upper track for BGM and the lower track for vocals.

Similarities Among Top Songs: There are notable similarities among the top songs, particularly in their BGM. These include periodic high-frequency pitches and a generally fast tempo with higher volume levels. In contrast, vocals tend to dominate the higher frequencies but exhibit relatively lower volumes. While further insights could be drawn from direct comparisons between specific songs, we do not delve deeper here.

Differences in Time-Frequency Characteristics Across Subgenres: In addition to similarities, distinct differences in time-frequency characteristics can be observed across subgenres. For instance, the frequency of high-pitched sounds in the BGM of Boom Amp is significantly lower compared to Trap. This highlights Trap as a genre characterized by faster tempos and more frequent intermittent high-frequency sounds, distinguishing it from other subgenres.

3.2 Pitch and Volume

We conducted a frame-by-frame analysis of pitch and volume for the top 10 songs in each subgenre, visualizing each song on a pixel display with the horizontal axis representing time. Each song features two tracks: the upper track for BGM and the lower track for vocals.

Similarities Among Top Songs: There are notable similarities among the top songs, particularly in their BGM. These include periodic high-frequency pitches and a generally fast tempo with higher volume levels. In contrast, vocals tend to dominate the higher frequencies but exhibit relatively lower volumes. While further insights could be drawn from direct comparisons between specific songs, we do not delve deeper here.

Differences in Time-Frequency Characteristics Across Subgenres: In addition to similarities, distinct differences in time-frequency characteristics can be observed across subgenres. For instance, the frequency of high-pitched sounds in the BGM of Boom Amp is significantly lower compared to Trap. This highlights Trap as a genre characterized by faster tempos and more frequent intermittent high-frequency sounds, distinguishing it from other subgenres.

3.2 Pitch and Volume

We conducted a frame-by-frame analysis of pitch and volume for the top 10 songs in each subgenre, visualizing each song on a pixel display with the horizontal axis representing time. Each song features two tracks: the upper track for BGM and the lower track for vocals.

Similarities Among Top Songs: There are notable similarities among the top songs, particularly in their BGM. These include periodic high-frequency pitches and a generally fast tempo with higher volume levels. In contrast, vocals tend to dominate the higher frequencies but exhibit relatively lower volumes. While further insights could be drawn from direct comparisons between specific songs, we do not delve deeper here.

Differences in Time-Frequency Characteristics Across Subgenres: In addition to similarities, distinct differences in time-frequency characteristics can be observed across subgenres. For instance, the frequency of high-pitched sounds in the BGM of Boom Amp is significantly lower compared to Trap. This highlights Trap as a genre characterized by faster tempos and more frequent intermittent high-frequency sounds, distinguishing it from other subgenres.

3.2 Pitch and Volume

We conducted a frame-by-frame analysis of pitch and volume for the top 10 songs in each subgenre, visualizing each song on a pixel display with the horizontal axis representing time. Each song features two tracks: the upper track for BGM and the lower track for vocals.

Similarities Among Top Songs: There are notable similarities among the top songs, particularly in their BGM. These include periodic high-frequency pitches and a generally fast tempo with higher volume levels. In contrast, vocals tend to dominate the higher frequencies but exhibit relatively lower volumes. While further insights could be drawn from direct comparisons between specific songs, we do not delve deeper here.

Differences in Time-Frequency Characteristics Across Subgenres: In addition to similarities, distinct differences in time-frequency characteristics can be observed across subgenres. For instance, the frequency of high-pitched sounds in the BGM of Boom Amp is significantly lower compared to Trap. This highlights Trap as a genre characterized by faster tempos and more frequent intermittent high-frequency sounds, distinguishing it from other subgenres.

3.2 Pitch and Volume

We conducted a frame-by-frame analysis of pitch and volume for the top 10 songs in each subgenre, visualizing each song on a pixel display with the horizontal axis representing time. Each song features two tracks: the upper track for BGM and the lower track for vocals.

Similarities Among Top Songs: There are notable similarities among the top songs, particularly in their BGM. These include periodic high-frequency pitches and a generally fast tempo with higher volume levels. In contrast, vocals tend to dominate the higher frequencies but exhibit relatively lower volumes. While further insights could be drawn from direct comparisons between specific songs, we do not delve deeper here.

Differences in Time-Frequency Characteristics Across Subgenres: In addition to similarities, distinct differences in time-frequency characteristics can be observed across subgenres. For instance, the frequency of high-pitched sounds in the BGM of Boom Amp is significantly lower compared to Trap. This highlights Trap as a genre characterized by faster tempos and more frequent intermittent high-frequency sounds, distinguishing it from other subgenres.

3.2 Pitch and Volume

We conducted a frame-by-frame analysis of pitch and volume for the top 10 songs in each subgenre, visualizing each song on a pixel display with the horizontal axis representing time. Each song features two tracks: the upper track for BGM and the lower track for vocals.

Similarities Among Top Songs: There are notable similarities among the top songs, particularly in their BGM. These include periodic high-frequency pitches and a generally fast tempo with higher volume levels. In contrast, vocals tend to dominate the higher frequencies but exhibit relatively lower volumes. While further insights could be drawn from direct comparisons between specific songs, we do not delve deeper here.

Differences in Time-Frequency Characteristics Across Subgenres: In addition to similarities, distinct differences in time-frequency characteristics can be observed across subgenres. For instance, the frequency of high-pitched sounds in the BGM of Boom Amp is significantly lower compared to Trap. This highlights Trap as a genre characterized by faster tempos and more frequent intermittent high-frequency sounds, distinguishing it from other subgenres.

3.2 Pitch and Volume

We conducted a frame-by-frame analysis of pitch and volume for the top 10 songs in each subgenre, visualizing each song on a pixel display with the horizontal axis representing time. Each song features two tracks: the upper track for BGM and the lower track for vocals.

Similarities Among Top Songs: There are notable similarities among the top songs, particularly in their BGM. These include periodic high-frequency pitches and a generally fast tempo with higher volume levels. In contrast, vocals tend to dominate the higher frequencies but exhibit relatively lower volumes. While further insights could be drawn from direct comparisons between specific songs, we do not delve deeper here.

Differences in Time-Frequency Characteristics Across Subgenres: In addition to similarities, distinct differences in time-frequency characteristics can be observed across subgenres. For instance, the frequency of high-pitched sounds in the BGM of Boom Amp is significantly lower compared to Trap. This highlights Trap as a genre characterized by faster tempos and more frequent intermittent high-frequency sounds, distinguishing it from other subgenres.

3.2 Pitch and Volume

We conducted a frame-by-frame analysis of pitch and volume for the top 10 songs in each subgenre, visualizing each song on a pixel display with the horizontal axis representing time. Each song features two tracks: the upper track for BGM and the lower track for vocals.

Similarities Among Top Songs: There are notable similarities among the top songs, particularly in their BGM. These include periodic high-frequency pitches and a generally fast tempo with higher volume levels. In contrast, vocals tend to dominate the higher frequencies but exhibit relatively lower volumes. While further insights could be drawn from direct comparisons between specific songs, we do not delve deeper here.

Differences in Time-Frequency Characteristics Across Subgenres: In addition to similarities, distinct differences in time-frequency characteristics can be observed across subgenres. For instance, the frequency of high-pitched sounds in the BGM of Boom Amp is significantly lower compared to Trap. This highlights Trap as a genre characterized by faster tempos and more frequent intermittent high-frequency sounds, distinguishing it from other subgenres.

3.2 Pitch and Volume

We conducted a frame-by-frame analysis of pitch and volume for the top 10 songs in each subgenre, visualizing each song on a pixel display with the horizontal axis representing time. Each song features two tracks: the upper track for BGM and the lower track for vocals.

Similarities Among Top Songs: There are notable similarities among the top songs, particularly in their BGM. These include periodic high-frequency pitches and a generally fast tempo with higher volume levels. In contrast, vocals tend to dominate the higher frequencies but exhibit relatively lower volumes. While further insights could be drawn from direct comparisons between specific songs, we do not delve deeper here.

Differences in Time-Frequency Characteristics Across Subgenres: In addition to similarities, distinct differences in time-frequency characteristics can be observed across subgenres. For instance, the frequency of high-pitched sounds in the BGM of Boom Amp is significantly lower compared to Trap. This highlights Trap as a genre characterized by faster tempos and more frequent intermittent high-frequency sounds, distinguishing it from other subgenres.