Foto: Flex Acoustics
Foto: Flex Acoustics

Great audio demands advanced research

Electrotechnology Sound
Cutting-edge research in optimal sound at pop and rock concerts is Danish, and has resulted in an invention that is now being installed in exclusive concert venues around the world.

Sound absorption and its significance to concert audio at rhythmic music venues is the theme of a new research project at DTU Electrical Engineering.

“A relatively comprehensive body of research into acoustics in venues for classical concerts already exists, but there aren’t many of us who are interested in the acoustics at venues for jazz, pop and rock. This is quite strange, given that it is in no way proportional to the number of venues and concerts staged in the two different branches of music,” explains Cheol-Ho Jeong, Associate Professor at DTU Electrical Engineering.

The new project is a collaborative venture with the internationally recognized researcher and specialist Niels Werner Adelman-Larsen, who is the only person in the world today who has devoted himself to in-depth study of the acoustics in venues for rhythmic music.

“The project focuses on reverberation time, using methods including taking a range of acoustic measurements in line with the ISO 3382 standard at selected venues. These measurements will then be backed by a survey among musicians and sound technicians, as well as statistical processing of the results,” adds Cheol-Ho Jeong.

As a part of his previous research, Niels Werner Adelman-Larsen has drawn up a set of guidelines for setting up music venues that host performances in different music genres, both classical and rhythmic. This is because different requirements apply to the reverb in the room depending on the genre of music.

“Classical music demands drawn-out reverberation, while the requirements for rhythmic are the diametric opposite. As such, the big pop and rock bands sound best at concerts if the lowest frequencies—i.e. the bass notes—have only a short period of reverb,” explains musician and MSc Eng Niels Werner Adelman-Larsen, who has been researching this area since his time studying at DTU

Research resulted in new product
Niels Werner Adelman-Larsen is not just a researcher, however. He is also a budding inventor. This combination has resulted in the company Flex Acoustics, which sells an inflatable membrane for use in concert halls, where it allows variable absorption of the low frequencies in the music.

Simply put, his invention is shaped like a giant, floating lilo, made of ultra-thin, fire-retardant plastic with a high level of inner damping that ‘swallows up’ the vibrations. When the concert hall is to be used for classical performance, air is released to extend the reverberation time. Conversely, air is pumped into the membrane to prepare for concerts of rhythmic music.

Thus far, membranes have been used at numerous events including the European Song Concert, which was held in Copenhagen in 2014, and have been sold to major international concert halls in countries such as Dubai, Kuwait and Korea. Most recently, the invention was used for a huge Rihanna concert at the Amsterdam ArenA.

Niels Werner Adelman-Larsen has neither finished his research nor completed work on refining his product.

“It is my interest in—and love of—music and pure sound that powers the work. I used to be a musician, and have travelled all over the country with my band. From personal experience, I know what a difference the acoustics make at a venue, and what this means for the concert experience as a whole,” he concludes.