Monday, February 9, 2015

More bass, please.

Newcomer Sam Smith and veteran Beck dominated the 57th edition of the Grammy Awards. Other outstanding winners were my favorite Eddie Vedder, now under his pseudonym 'Jerome Turner' and Pearl Jam's Jeff Ament scoring Best Recording Package. Beyonc√© took home Best Surround Sound Album.
As I was reviewing the winner list, I came across an interesting study by Alex Wilson, PhD Student at the Acoustics Research Centre, University of Salford, England. In his study, Mr. Wilson reflects on the fact that for the last thirty years, pop music has been... all about that bass.
Mr. Wilson came to this conclusion by analyzing trends in audio production, calculating audio features from 10 songs per year since the launch of the Compact Disc in 1982 and plotting the data against year of release. A revealing feature to look at is the bass (low-frequency content).

Mr. Wilson observed the percentage of the total spectral energy below 80 Hz (LF energy). This frequency was chosen because this is a typical crossover frequency for high-end studio subwoofers.

Frequency spectrum
Figure 1. Frequency spectrum of All About That Bass by Meghan Trainor

The figure below uses LF Energy to demonstrate the gradual trend of increasing bass in music. 

Increase in LF-ENERGY
Figure 2. Increase in bass (LF Energy) over 33 years

A quick Internet search reveals an insight into how we understood the term “bass” in 2014. The top result is the song, performed by Meghan Trainor, All About That Bass. Under the assumption that the song’s lyrics are literal and refer to preferred frequency balance in pop music, we can test the notion that All About That Bass is truly all about that bass and also has “no treble”.

As shown in Figure 2 above, however, the LF Energy value for Trainor’s song is right on the smoothed line, and so the amount of bass is typical for 2014. Perhaps it is simply the lyrics that draw our attention to the bass instruments in the mix. Perhaps these results can shed some light on the songs popularity – that the frequency content is not too much or not too little of any particular parameter and sits in the “Goldilocks Zone”, where conditions are perfect for a hit record.

There have been studies on the perception and preference of “exaggerated bass”. There are also a number of possible reasons for modern productions having more bass.
  • While acoustic instruments would typically be quite large in order to generate low-frequencies (think of large drums or organ pipes), the increased use of electronic instruments and synthesis means this is no longer a restriction.
  • Loudspeaker technology has improved such that we can reproduce these lower frequencies more easily in the home without the need for excessively large loudspeakers.
  • Innumerable songs which refer to the Roland TR-808 drum machine, particularly it’s bass drum sound, as something desirable, since many experts agree that  “nothing sounds quite like an 808”.
This is supported by a recent study in which the spectral characteristics of pop music recording since 1950 were gathered [3]. This has shown that the amplitude has increased at low frequencies and the frequency at which the bass is loudest has also decreased. This is dependent on genre, with hip-hop showing the highest bass levels and the lowest for jazz, which may rely more on acoustic instruments. Perhaps unsurprisingly, pop music lies in the middle.
Bass content of different genres
Bass content of different genres [3]

All About That Bass” was nominated in the Record Of The Year and Song Of The Year categories at the 57th Annual Grammy Awards. The winner of both categories was Sam Smith.  

References: Alex Wilson post 'All about that bass' 02.07.2015


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