The intensity of sound is typically measured in decibels (dB), which is a logarithmic scale. When the intensity of a sound is doubled, it corresponds to an increase of approximately 3 dB.
To clarify, a faintest audible sound is often defined as having an intensity of around 0 dB, although it can vary depending on the individual and the context. If we double this intensity, we would have an intensity of approximately 3 dB. Similarly, if we double the intensity again, we would have an intensity of approximately 6 dB.
Keep in mind that this is a simplified explanation, and the actual perception of loudness can be influenced by various factors, including the frequency content of the sound and individual hearing capabilities.