Before improving office acoustics, it's essential to understand the current situation. Many interventions are based on subjective perceptions, but without concrete data, it's difficult to assess the problem and verify the solution's effectiveness. Measuring noise levels using a clear methodology allows for fact-based decision-making. This article explains the applicable regulations, the instruments used for measurement, and how to interpret the results.
Why Measure Before Intervening
In an office, noise rarely comes from a single source. Conversations, calls, equipment, air conditioning, and noise from the street all contribute. The result is a continuous background noise that is difficult to identify without instruments. Complaints from the team alone don't indicate where to intervene. Two areas can generate the same number of comments but have very different noise levels. Measurement provides an objective picture of the initial situation and a point of comparison to later verify whether the investment has paid off.
Reference Standards
There is no single standard regulating ambient noise in offices in Spain, but several references establish a clear framework. The INSST's NTP 503 is the most specific: it recommends a maximum of 40 dB(A) in offices and concentration rooms, and up to 50 dB(A) in more active administrative spaces. It is not mandatory, but it is commonly used as a criterion in assessments and projects. The WHO sets the threshold at 55 dB for customer service tasks and at 45 dB for work requiring sustained concentration.
At the construction level, the CTE DB-HR (Spanish Building Code, Basic Document on Noise Reduction) regulates noise transmission between rooms and from the outside. And the WELL and LEED certifications include acoustic comfort credits that require documented measurements before and after the intervention.
What is used to measure noise levels?
The main instrument is a sound level meter, which captures the sound pressure at a point and converts it into a decibel value. For office diagnostics, a calibrated Class 2 sound level meter is usually sufficient. If the results are for an expert report or a certification process, a Class 1 meter is required. The sound level meter must be calibrated before and after each session using a reference calibrator. If the reading has changed between the two checks, the data for that session is invalid.
Mobile sound level meter apps are useful for getting a quick idea, but not for a diagnostic assessment: the microphone is optimized for voice, and the typical margin of error is between 5 and 10 dB.
How to take the measurement
Representative points must be selected in each functional area: open workstations, meeting rooms, passageways, and break areas. As a general guideline, one point should be used for every 25 to 50 square meters in open areas and at least one point per enclosed room. The device should be positioned at ear level for a seated person, between 1.10 and 1.30 meters from the floor, and at least one meter away from walls and windows. On a table or against a partition, nearby reflections will distort the reading. Measurements should be taken during normal activity hours, in at least two different time periods, with recordings of at least 15 minutes per point. A measurement taken first thing in the morning or during a lunch break will not reflect the actual situation. Each measurement point should be accompanied by a contextual record: how many people were present, whether the air conditioning was on, and if there were any unusual noise sources. Without this information, comparing two measurements taken on different dates is meaningless.
Common Mistakes
The most common mistake is measuring at a single point and extrapolating the result to the entire floor. In an open-plan office, noise levels can vary by several decibels between areas separated by only a few meters.
Taking a single instantaneous reading is also common. The level fluctuates constantly, so a single reading reveals little about the actual experience of those working there.
And it's important not to confuse noise level with acoustic quality. A room can be below 45 dB(A) and still be uncomfortable if the sound echoes and conversations are difficult to understand from a distance.
How to Interpret the Results
The most widely used parameter is LAeq, the equivalent continuous sound pressure level, which expresses the average noise level during the measurement period. This is the data point that is compared with the limits of NTP 503 and with WHO recommendations. Along with this, it's advisable to consider LAFmax, which records the highest peak and detects very annoying isolated events even if they don't significantly affect the average, and L90, which estimates the background noise of the space. Reverberation time measures how long it takes for sound to decay once the source stops. In offices, values below 0.6 seconds are recommended in open areas and 0.5 seconds in meeting rooms. It's the parameter that best explains the feeling of a noisy room when the decibel level isn't high.
If you want to review the fundamentals, you can consult our article on basic acoustics concepts.
Best practices: from measurement to solution
Before intervening, it's advisable to take a complete measurement to serve as a baseline. Without this data, there's no way to verify if the acoustic solution has worked.
During the diagnosis, the data should be cross-referenced with the team's observations. Sometimes the area with the highest decibel level isn't the one generating the most complaints, because the type of noise matters as much as its volume.
With the results in hand, the appropriate intervention can be chosen. If the main problem is reverberation in open areas, Ideacustic ceiling panels effectively reduce reverberation time. If privacy is lacking for calls or meetings, Ideazone acoustic booths allow you to create enclosed spaces without any construction work. After installation, measurements must be repeated at the same points and under the same conditions. Comparing the before and after allows you to quantify the improvement and justify it to management. In our guide on acoustic conditioning in offices, we explain the most common solutions for this type of intervention.
Do you need a professional acoustic assessment?
If noise is a problem in your office, Ideatec can help. We design and manufacture custom acoustic conditioning solutions, from Ideacustic ceiling panels to Ideazone acoustic booths for creating privacy zones within open-plan offices.
Consult with our team and plan your intervention based on real data.