Digital sound has won out: The long and winding road from mono to 3D

Illustration: Laurids Hovgaard

When the old Radio Centre in Frederiksberg, Copenhagen first began to broadcast news, classical music and radio plays, it was done using analogue methods, on mono, reel-to-reel tapes. That was in 1940.

Today, the house is still filled with beautiful wooden panels and classical instruments – but now the music is played by the students of the Royal Danish Academy of Music, which has taken over the building. However, if you look closely along the walls and ceiling of the trapezoidal concert hall, modern technology is evident everywhere.

Tonmeister Jesper Andersen is currently making spatial, three-dimensional recordings of classical music in the Dolby Atmos format. The recordings can be played back in 3D through 44 speakers and four subwoofers placed in a hemisphere around the hall, creating a so-called sound field where the music envelops the listener.

In many ways, the Radio Centre Concert Hall tells the story of the explosive development in the technology of recording and reproducing music, which is barely 100 years old.

“It’s pretty amazing to think that just 100 years ago, people only heard music when it was played by musicians, in church or in concert halls. Today, we all walk around with music players in our pockets and speakers in our ears,” says Jesper Andersen, head of the Academy’s tonmeister programme.

He is also a Grammy-nominated producer, sound engineer and pianist, and has recorded some 100 CDs and produced music for radio, television and theatre.

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Despite the name, the training of sound engineers and producers is not an engineering degree in acoustics.

“We don’t work with sound, but with music, which also happens to be sound. So our use of technology depends on the music that we are recording or playing,” says Jesper Andersen.

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The great sound war

Ever since the first digital recordings replaced analogue, reel-to-reel tapes back in the 1970s, the debate has raged among audiophile engineers about which technology provides the best sound quality.

But now, whether you ask professors of acoustics at the Technical University of Denmark (DTU), or B&O in Struer, or the sound engineers in the Radio Centre, the debate has moved on from a two-sided war between analogue and digital to a multifaceted discussion about a broad palette of technologies that can be mixed and matched across the board.

Mads Græsbøll Christensen, professor of acoustics at Aalborg University, sums it up well:
“I think most people have realised that the possibilities of digital far outstrip analogue. But I still use a valve amp when I play guitar.”

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Today, the music defines the choice of technology – not so much the other way round. At one end of the scale we find classical music, which should preferably be reproduced as transparently as possible.

“Mozart is the star, and his music is so brilliant that it’s still hard to understand how it was possible for him to write so much of it. On the other hand, when we listen to pop music, it’s the artist who is the star, while few people know who the composer is,” explains Jesper Andersen, who hastens to point out that he enjoys both Lady Gaga and Mozart.

Here, Danish DPA Microphones and DAD – Digital Audio Denmark – are among the most used microphones and converters for classical music recordings, where the sound must be reproduced without colouration, and where there is room for large fluctuations in volume.

On the reproduction side, B&O’s Head of Research Søren Bech is an expert in how to quantify human sound impressions – i.e. how to measure sound quality.

“Digital vs. analogue has ended up as a religious war, and I’m not very interested in that. We wanted to be able to objectively measure how people experience reproduced sound, and here we can see that carrying out listening tests with both trained sound engineers and ordinary consumers is the best way to evaluate sound quality,” he says.

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Music on the move

Ever since the Danish American Peter L. Jensen presented the first commercial moving-coil speaker in 1915, sound quality has been getting better and better. Just think of the revolution when sound engineers went from recording a single mono channel to recording in 24 tracks and delivering a result in stereo.

But on the cusp of the 1980s, things started to move in a different direction. Sony introduced the Walkman portable cassette player, and digital formats gained ground in the wake of Motorola’s famous 6502 8-bit processor, which drove down the price of microchips.

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“Traditionally, recording technology was developed for use by a very small market of music professionals. The big shift from analogue to digital came when we were able to use computers for music. Then the price of the equipment dropped, and the possibility of making good recordings was no longer so exclusive,” says Jesper Andersen.

Music production was suddenly available to all. But that availability also came at a price, which was compressed audio, because storage space was extremely limited. It was the start of a period that led many music lovers to swear by analogue formats like vinyl.

Louder, louder...

This only got worse in the mid-1990s, when MP3 players took off. Now the sound really had to be squeezed into very little space. While CDs have a bit rate of 1,411 kbit/s (a sampling rate of 44.1 kHz times 16 bits, times two channels), the MP3 format has just 320 kbit/s.

At the same time, the volume war began.

“Producers began to compete to record as loudly as possible. This was a cheap trick to get attention on the radio. Scientific experiments show that if one recording is played back slightly louder than another, people tend to mistake it for better sound quality,” says Jesper Andersen.

This quickly compromised the dynamics of the music, which are expressed as fluctuations in volume. A good example is the monster hit Wonderwall by the British band Oasis, which was cranked all the way up to the point at which the amp can no longer work with the input voltage and starts clipping the top and bottom of the signal.

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In the hour of need, it was – somewhat surprisingly – YouTube and Spotify who finally put an end to the volume war. They did this with the LUFS standard, ‘Loudness Units relative to Full Scale’, which means that producers can no longer score cheap points by turning up the volume.

“It really made the champagne bottles pop in the music industry when loudness was no longer rewarded, and we could once again make music with space and dynamics that would still be highlighted on the streaming services,” says Jesper Andersen.

But the combination of compressed MP3 sound, high sound volume and cheap speakers has left its mark on generations from the 1990s onwards.

“The experience of ordinary people, especially the young, is very different today, compared to a few decades ago. My daughter is used to listening to music on her tiny ear buds, and when she comes home and listens to music on my speakers where the bass is good, she has an ‘aha’ experience. She can quite simply hear elements in the music that were previously hidden, because the frequency range was restricted,” says Søren Bech.

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Sound goes 3D

Because we are all now online with access to unlimited cloud storage space, there is a growing range of new, lossless music services, offering high-end streaming with high sample and bit rates.

“If you have both a good converter and good speakers or headphones, then high sample rates might make sense. But if you mostly listen to pop music then it’s hard to hear the difference, because the dynamics are very limited,” says Jesper Andersen.

Several streaming services now offer music at a 96 kHz sampling rate, compared to the traditional 44.1 kHz. It looks better on paper, but not everyone will notice.

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“The human hearing range goes from 20 to 20,000 Hz, so it shouldn’t make much difference. It might have a slight impact when recording, because the processing functions better at higher sample rates. But I wouldn’t bet much that I could hear the difference between ordinary streaming and the new high sample rate services if I’m listening to pop music on my smartphone,” says Jesper Andersen.

Either way, Jesper Andersen has plenty of audio optimism:

“I think we’re heading back towards better sound quality. Storage space is no longer a bottleneck, and you can now also buy very good equipment for relatively little money – even the wireless ear buds are approaching good quality.”

That’s why he’s teaching the next generation of producers and sound engineers how to handle the recording and playback of 3D sound in Dolby Atmos.

He predicts that in the future, new music will come in three formats: conventional stereo, binaural recordings targeted at headphones, and 3D sound in Dolby Atmos targeted at a large speaker system with more than ten speakers.

“But I don’t think we can expect everyone to have lots of speakers in the living room, so the stereo format will live on,” says Jesper Andersen.

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Photo captions:

Jesper Andersen is head of the tonmeister (recording director) study programme at the Royal Danish Academy of Music. Here it is the music, rather than the technology, that dictates how recordings are made. Illustration: Laurids Hovgaard

The Royal Danish Academy of Music moved into the Radio Centre in 2008, when the Danish Broadcasting Corporation moved to the Copenhagen district of Ørestad. Illustration: Laurids Hovgaard

At the Academy of Music, recordings are made with both digital 3D Dolby Atmos and old-fashioned analogue tools. Illustration: Laurids Hovgaard