Researchers from Oldenburg have discovered that lead singers used to be significantly louder in relation to the rest of their band than they are today – and piqued the interest of numerous media outlets with this finding.
A world-famous musician being interviewed about the results of research at the University of Oldenburg is certainly not an everyday occurrence, yet that's exactly what happened recently on US radio network NPR's afternoon radio programme All Things Considered. Indie rocker Beck, whose best-known hit "Loser" from 1993 is still popular today, talked about his views on the findings.
The interview was prompted by a paper published by Oldenburg hearing researcher and musicologist Dr Kai Siedenburg together with his former student Karsten Gerdes in the Acoustical Society of America's open-access journal JASA Express Letters. The two scientists analysed more than 700 songs that reached the top of the US Billboard Hot 100 charts or were nominated for a Grammy between 1946 and 2020, including several tracks by Beck. Their goal was to learn more about how popular songs are mixed and draw conclusions about how to mix music for people with hearing loss.
The researchers focused on the difference in volume between the lead vocal and the accompanying instruments and found that during the first 30 years covered in their study this difference had gradually decreased. In other words, the music was mixed in such a way that the volume of the lead vocal came ever closer to that of the instruments. This trend ended in the mid-1970s, when the difference in volume levelled off at an average of about one decibel, having peaked at around five decibels in previous decades. "Advances in recording technology probably played a role in decreasing the difference in sound levels," observes Siedenburg. "A big step was the possibility to mix music stereophonically, in other words, arrange it in such a way that, for instance, the rhythm guitars were placed on the outside of the mix and the vocals were centred." With this technique, the human voice gets the desired amount attention even if it is only minimally louder than the instruments.
Within this general trend, however, the researchers also observed measurable differences between the various music genres. They found that country songs have the loudest lead vocals in relation to the accompanying instruments, followed by rap, pop and then rock. Metal was at the lowest end of the scale: in this genre, the lead voice is generally mixed to be quieter than the instruments.
The results of the Oldenburg research sparked a wave of interest in mainstream media after the scientific journal published a press release on the paper. The German dailies Tagesschau.de and Tagesspiegel as well as radio station Radio Eins, the UK's Daily Mail, Austrian state broadcaster ORF and many other outlets reported that "lead vocalists are getting quieter". Siedenburg was surprised by the level of interest his article has generated. "I suspect it has to do with the fact that the paper's message is catchy and easy to understand," he says. "Besides, you can put a picture of your favourite star next to it," he adds with a chuckle.
The hearing and music researcher was particularly pleased to be contacted by American radio station NPR, which he himself used to enjoy listening to when he was a student. In addition to Siedenburg, the radio station's reporter also interviewed Reba Meyers, lead singer of the 2021 Grammy Award-winning hardcore punk band Code Orange. Meyers explained that many rock and metal bands mix their songs on the computer, where an endless amount of tracks are available, so they can use a lot of layers that then end up competing with the vocal. The songs by singer Beck, whose music doesn't have much to do with metal, were also conspicuous in the study in that the lead vocal is mixed to be uncharacteristically quiet, and sometimes even quieter than the instruments. This effect is deliberate. As Beck explained in the interview: "I came up more in the indie rock genre, alternative music. And the ethos of that time was to really bury the vocal. You didn't want people to hear what you were saying."
For Kai Siedenburg, by contrast, intelligibility is a top priority. When it comes to adapting music to ensure that it sounds good also to people using hearing aids, the lead-vocal-to-accompaniment-level-ratios play a key role. "Now we know that there are genre-specific volume ratios, this is a basis we can build on when making further genre-specific modifications," says Siedenburg.