Which of the following sound properties can help us to increase the sound from feeble to loud?

When we change feeble sound to loud sound, we increase its amplitude.
Sound frequency is defined as the number of vibrations per second. It is simply the inverse of time. It is measured in $\mathrm{Hertz}$. The maximum displacement of the wave from the mean position 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 in a sound wave is defined as its wavelength.
Among these, the amplitude is the quantity that determines how loud a sound is.
The amplitude of the sound is directly proportional to its loudness. The larger the amplitude, the louder the sound and the more energy the sound waves contain. As a result, when we convert a weak sound to a loud sound, we increase its amplitude.