Controlling bass frequencies – Espoo to reduce noise of outdoor concerts without compromising event experience

Espoo will control the lowest frequencies of open-air concerts, i.e. so-called bass frequencies, because they are the frequencies that carry over through building structures and cause the greatest noise nuisance to the neighbours. Espoo will implement C frequency weighting for bass frequencies when determining limit values for music noise. The heavy sound of a bass carries farther than, for example, singing and other higher sound frequencies of music, the intensity of which is measured by looking at the A frequency weighting.

“The idea of controlling bass frequencies arose from residents contacting us. Whenever residents complain about open-air concerts, the complaints are due to heavy bass. We want to minimise the noise nuisance of open-air concerts without compromising the vitality of events. In this way, organising events in Espoo will remain meaningful,” says Eero Lahtela, Environmental Inspector at the City of Espoo. 

Espoo is expected to host about ten large open-air concerts this summer, including the wine festival Espoon Viinijuhlat in Haukilahti and a series of events at Tapiolan kulttuuriaukio square. Event organisers have been very accepting of the new noise regulations and festival audiences need not worry about the sound quality of upcoming performances. 

“Musically, the festival atmosphere will be the same as before, because in the event area, you can still feel the rhythm of the bass in your body. The only change is that the neighbours will have a better chance of getting a good night’s sleep,” says Lahtela. 

The policy in Espoo is that if music is played in a large open-air concert after 20:00, the event organiser must submit a noise notification to Environmental Protection. The city’s noise notification decision obliges the organiser to control and monitor the noise nuisance. Espoo’s means for this are event-specific noise limit values, and the policy that if there is residential buildings near the venue, open-air concerts must end by midnight. 

Event organisers design the best noise management means themselves. Bass frequencies carrying over to neighbouring areas can be reduced by adjusting their volume, erecting noise barriers or using several small speakers instead of one big speaker.

Event organisers should orient their stages so that they cause as little noise nuisance as possible to the neighbourhood. Communication is also important: if nearby residents know about an event in advance, they can prepare for it by purchasing earplugs, spending the night elsewhere if possible, or closing the windows. 

“From the feedback we receive from residents during the summer, we can infer how limiting the bass frequencies affects the noise nuisance. Other municipalities can later benefit from the pioneering work carried out by Espoo,” Lahtela says. 

Urban events in Espoo in 2024 (in Finnish).(external link, opens in a new window)

Information about decibels:

• Decibel (dB) is the unit used to measure volume.
• The unit dB(A) is used to measure volumes that can be heard with human ears.
• dB(C) is used to measure the intensity of very high or very low frequencies. The low frequencies that a person feels as a vibration in their body are often referred to as bass or low frequencies.