If weak sound is converted into a loud sound, _____________ increases. 

The loudness of the sound is characterised by the energy of sound. A loud sound is heard till a greater distance whereas a feeble sound diminishes in a smaller distance and is not heard at far off points. Recall the elements that influence the volume or intensity of sound.

Sound frequency is defined as the number of vibrations per second. It is simply the inverse of time. It is measured in Hertz. The largest displacement of the wave from the mean location is defined as the amplitude. The speed of sound is defined as the distance travelled by sound per unit time.

The distance between two adjacent crests or troughs of a sound wave is defined as its wavelength.

Among these, amplitude is the quantity that governs how loud a sound is.

The amplitude of sound is exactly proportional to its loudness. The greater the amplitude, the louder the sound and the greater the energy contained in the sound waves. As a result, when we transform a weak sound into a loud sound, we increase its amplitude.

Hence, If we change a weak sound into a loud sound, we increase amplitude.