NCIDQ IDFX Practice Exam

How noticeable is a noise reduction change of 3dB in a space?

1. Very noticeable

2. Hardly noticeable

3. Moderately noticeable

4. Extremely noticeable

The correct answer is: Hardly noticeable

A change in noise level of 3 dB is considered hardly noticeable to the average listener. This is primarily because human perception of sound is logarithmic rather than linear; meaning we perceive changes in sound levels relative to the current sound level. A 3 dB reduction signifies a halving of the sound intensity, but this reduction is generally beyond what most might recognize without being specifically tuned into the change or measuring it. In practical terms, for indoor environments, people often require a change of about 5 dB to perceive a difference in volume as noticeable. Consequently, while there may be theoretical changes that are measurable, the actual auditory experience of a 3 dB change is subtle and likely goes unnoticed in the context of typical background noise levels.