The main goal for acoustic design in a space is to keep the background noise levels low enough that normal speech (or other special sound, like music) is easily understood. Since humans detect frequencies differently, sound criteria are measured with curves across a range of frequencies.

For instance, a 40 dB sound at 1000 Hz frequency would seem louder than a 50 dB sound at 80 Hz frequency – even though the sound pressure is higher in the 80Hz sound, our ears are not as sensitive to it as they are to the 1000 Hz frequency. Outside of that general range, we aren’t concerned about whether the sound levels are very high or low (for architecture, at least).īefore you can begin to understand the various rating criteria, it is important to understand that humans detect varying frequencies differently because the human ear is less sensitive to very high and very low frequencies. They can easily detect a 5 dB change in sound level under most conditions.ĭecibel A : dB(A) is simply a filter that adjusts decibels for the frequency range that the human ear is capable of hearing, which is in the range of 1 kHz to 4 kHz. Humans can just barely detect a 3 dB sound level difference. As a general rule of thumb, an increase of 10 dB means the sound is perceived to be twice as loud – however this can vary based on the type of sound and the listening conditions. Keep in mind that sound pressure increases on a logarithmic scale. There are different measurements for different conditions, so let’s take a look at them.ĭecibels : The decibel is used in acoustics as the standard unit of sound pressure level, or the loudness of a sound. Unfortunately, it isn’t as simple as saying the sound in a bedroom should be 30 dB or lower. Measuring Sound Levelsīefore you can determine the appropriate sound level for your space, we need to discuss the various ways of measuring sound. Be sure to check our article Architectural Acoustics - Controlling Sound, which talks about design methods for controlling sound. Part of that is to control sound sources.

This article discusses acceptable sound levels within a room. Table of Acceptable Room / Space Sound Levels.So Which Noise Criteria Should be Used?.

Sound decibel chart