(SOUNDBITE OF SONG, "ALL SHOOK UP")
ELVIS PRESLEY: (Singing) Well, a-bless my soul, but what's wrong with me?
JUANA SUMMERS, HOST:
On Elvis Presley's 1957 hit "All Shook Up," you can hear his voice floating above the rollicking sound of the band.
(SOUNDBITE OF SONG, "ALL SHOOK UP")
PRESLEY: (Singing) I'm all shook up, mm-mm (ph).
SUMMERS: It was a common feature of music back then - vocals in the foreground, band behind.
SACHA PFEIFFER, HOST:
But acoustic scientists in Germany have found that lead singers have been getting quieter over the years in relation to their bands.
KAI SIEDENBURG: We find that vocal levels are decreasing in popular music.
PFEIFFER: Kai Siedenburg and his colleague analyzed hundreds of chart-topping songs from 1946 to 2020, and when they compared the loudness of singers to everything else - guitars, drums and so on - they found that trend was particularly true for certain genres.
SIEDENBURG: The differences across musical genres are quite substantial, so rock and metal have really much-reduced vocal levels, especially metal.
(SOUNDBITE OF SONG, "UNDERNEATH")
CODE ORANGE: (Singing) The guinea pigs of a generation.
SUMMERS: One example from the study - the 2020 track "Underneath" by the group Code Orange. Here's guitarist and singer Reba Meyers.
REBA MEYERS: So it's a different style. It kind of treats the voice slightly more as an instrument as opposed to the lead.
(SOUNDBITE OF SONG, "UNDERNEATH")
CODE ORANGE: (Singing) I was just too deep in to fail.
SUMMERS: She says modern recording technology could be a factor.
MEYERS: In rock music and metal music, a lot of bands are writing songs in digital workstations, on the computer where you have an endless amount of tracks to use, so it's really easy to use a lot of layers that then end up competing with the vocal.
PFEIFFER: Another song that exemplifies the trend is Beck's 1996 track "Where It's At."
(SOUNDBITE OF SONG, "WHERE IT'S AT")
BECK: (Singing) Where it's at. I got two turntables and a microphone.
PFEIFFER: Beck had several songs in this analysis, all of which have vocals about the same loudness or quieter than the instruments. And he said for him, lowering the vocals was a deliberate act.
BECK: Like, I came up more in the indie rock genre, alternative music. And the ethos of that time was to really bury the vocal. People - you didn't want people to hear what you were saying.
(SOUNDBITE OF SONG, "WHERE IT'S AT")
BECK: (Singing) And your whip-flash tones. Members only, hypnotizers. Move through the room...
The track and the rhythm has to be at the forefront if you want to move people. As soon as you put the vocal up at the forefront, the track loses its energy and its immediacy.
(SOUNDBITE OF BECK SONG, "NAUSEA")
SUMMERS: Not that the scientist behind the study, Kai Siedenburg, expects artists like Beck to be reading the Journal of the Acoustical Society of America, where his research appeared.
SIEDENBURG: They should just do what they do and generate the music they love.
SUMMERS: Even if that means the lead vocals aren't leading the way as much as they used to.
(SOUNDBITE OF SONG, "NAUSEA")
BECK: (Singing) And we're gone. It's nausea, oh, nausea, and we're gone. Transcript provided by NPR, Copyright NPR.