How many dB change is required for people to perceive a change in sound that is either twice or half as loud?

The perception of sound loudness is somewhat logarithmic, meaning that our ears perceive changes in sound levels in a specific way. To perceive a sound as being either twice as loud or half as loud, a change of approximately 10 decibels (dB) is generally required. This threshold is based on the way human hearing works; it is widely acknowledged in acoustics that a change of about 10 dB corresponds to a perceived doubling or halving of loudness.

For instance, if a sound is measured at 70 dB, increasing it to 80 dB would typically be perceived as being significantly louder—around twice as loud—by most people. Conversely, reducing that 70 dB sound to 60 dB would generally be perceived as about half as loud. This concept is essential in audio engineering and sound design, as professionals consistently apply this understanding to create appropriate audio levels for various environments and applications.

Other options present sound level changes that exceed the threshold needed for perceived loudness adjustments. Therefore, while changes of 5 dB, 15 dB, and 20 dB do represent loudness adjustments, they are not the thresholds most commonly associated with the auditory perception of doubling or halving volume.