Described in detail herein are methods and systems for estimating storage capacity of a storage unit disposed in a facility based on echoes detected by microphones. The microphones can detect sounds generated in the warehouse and reflected off the storage unit structures. The microphones detect the intensity of the sounds. The microphones can encode the sounds and the intensity of the sounds in time- varying electrical signals and transmit the time-varying electrical signals to a computing system. The computing system can decode the sounds and the intensity of the sounds from the time- varying electrical signals and estimate storage capacity of a storage unit from which the sounds reflected off of based on the intensity of the sounds.