Carrie Underwood singing in concert

Country superstar Carrie Underwood performing on the LP Field stage during CMA Fest 2013 in Nashville, Tennessee. (Photo by tncountryfan is licensed under CC BY 2.0. To view a copy of this license, visit

WASHINGTON — A new study reveals that the volume of lead singers in chart-topping songs has gradually decreased over the past 75 years. Traditionally, music has focused on emphasizing the lead singer’s voice, but researchers have discovered that these vocals are becoming increasingly quieter compared to the rest of the band.

Previous research has suggested that studios mix lead vocals at a higher volume than other instruments on the track. However, scientists at the University of Oldenburg (UO) in Germany found the opposite to be true when they analyzed a more comprehensive selection of songs representative of popular Western music.

The research team examined the top four tracks from the Billboard Hot 100 each year between 1946 and 2020, choosing this particular chart for its diversity and independence. They isolated lead vocals from other sounds in the 300 selected songs to calculate the lead vocal-to-accompaniment ratio (LAR).

The study attributes the decline in LAR to changes in music technology, but researchers also suggest that it could be related to the “stylistic evolution” of pop songs. In a follow-up investigation, study authors found country music has the highest LAR, followed by rap and pop. Rock music had an almost zero LAR, while metal had a negative LAR, and solo singers had a much higher LAR than bands.

The Billboard Charts are considered independent and representative due to their diversity. Our analysis showed a significant downward trend in the LAR, from about 5 decibels in 1946 to approximately 1 decibel in 1975, after which the LAR remained constant,” explains Karsten Gerdes, an MA student at UO, in a media release.

music volume by genre
Estimated lead-to-accompaniment-ratio, LAR, for songs in five genres from 1990-2020. Purple circles correspond to solo artists and green squares to bands. CREDIT: Kai Siedenburg

Is the guitar the new ‘lead vocal’?

Since most recordings are not available as separate tracks for individual instruments, researchers utilized software to divide each song into tracks for vocals, bass, percussion, and other remaining sounds. The program also removed backing vocals to measure the volume of only the lead singer.

To investigate whether changing pop song styles contributed to quieter leads, the researchers examined tracks nominated for Grammy Awards in the genres of country, rap, pop, rock, and metal. They calculated sound amplitudes by subtracting the decibel level of the track from the maximum decibel of the lead vocal.

“Another possibility involves the stylistic evolution within popular music. Guitar riffs are a distinctive feature of rock and metal, with guitars taking a position comparable to lead vocals,” concludes UO’s Kai Siedenburg.

The study is published in the journal JASA Express Letters.

What is the Billboard Hot 100?

The list is a weekly chart that ranks the top 100 songs in the United States. It is compiled by Billboard, a popular music industry magazine and website. The rankings are based on a combination of factors that measure the popularity of songs, which include:

  • Radio airplay: The number of times a song is played on various radio stations across different formats (such as pop, adult contemporary, and R&B/hip-hop) is measured through Nielsen Broadcast Data Systems (BDS). Radio airplay data are gathered from over 1,600 radio stations in the United States.
  • Streaming data: The number of streams on popular on-demand music streaming services like Spotify, Apple Music, and Amazon Music are also taken into account. This data is provided by Nielsen Music Connect.
  • Sales data: Digital downloads and physical sales of singles also contribute to the Billboard Hot 100 rankings. Nielsen SoundScan is responsible for tracking sales data from digital retailers, brick-and-mortar stores, and direct-to-consumer transactions.

The data from these sources is combined to create a points-based system, with each component (airplay, streaming, and sales) weighted differently. This system is then used to determine the rankings for the Billboard Hot 100 chart, which is updated and published on a weekly basis.

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South West News Service writer Pol Allingham contributed to this report.

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