nnovations in analog-to-digital conversion methods have improved the accuracy by which analog sound is replicated. Example,DVD audio.

Sound is created by a vibrating object. Sound travels as a wave through a medium, for example, a liquid (such as water), a solid (such as the seafloor), or a gas (such as air).

The recording method plays a big role
Sound waves can be stored on an analog master record and then transformed to a digital audio format using an analog-to-digital converter (ADC), or it can be recorded directly on a digital medium. Once the audio is played the digital signal is converted back into an analog sound wave using a digital-to-analog converter (DAC). Having suffered compression and then expansion, the integrity of the original sound is compromised.

Analog sound
Sound itself is a continuous wave; it is an analog signal. This means that one cannot detect the precise moment the pitch changes.

Digital sound
Digital sound is not a recording of the actual sound, but rather a combination of binary code, the utmost simplest machine language of zeros and ones, representing the sound's intensity and pitch at precise intervals with relative accuracy.

Sound can also be propelled through water by small variations in the water pressure. The human ear is not suited to this, but a whale has excellent underwater hearing .