It is true that the greater the amplitude of a sound wave, the louder the sound. Amplitude is defined as the measure of change in atmospheric pressure caused by sound waves.
Amplitude is measured in the amount of force applied over an area and is most commonly measured in newtons per square meter (N/m2). A newton is considered the amount of force it takes to accelerate a 1-kilogram object by 1 meter per second (m/s).
The lowest threshold that a human can hear sound is 0.00002 N/m2. The threshold of pain for hearing a sound is considered to be 60 N/m2. Both of these numbers can vary depending on the individual and age but can be used as general guidelines.