How much sound intensity is needed to perceive sound as being twice as loud?

To perceive sound as being twice as loud, an increase of approximately 10 decibels (dB) is necessary. This is based on the logarithmic nature of human hearing and sound intensity perception. The decibel scale is logarithmic, meaning that each increase of 10 dB corresponds to an intensity increase by a factor of ten.

However, our perception of loudness is not linear but rather exponential, where a change of about 10 dB is often equated with a doubling or halving of perceived loudness. Hence, if you start at a certain intensity level and increase it by 10 dB, the sound will be perceived as roughly twice as loud. This principle is widely established in audiology and acoustics, making 10 dB the correct choice for this question.