Fundamentals of Digital Sound Technology

Digital Sound Fundamentals

Sound is a vibrational phenomenon transmitted in the form of waves propagating in a determined elastic medium. When the vibrations are produced arbitrarily, without any rhythmic sequencing, we are talking about noise.

Characteristics of Sound

• Tone: Wave magnitude that tells us the number of complete vibrations that take place during 1 second. It is measured in Hz. Sound waves lower than the audible limit are called infrasound, and the higher ones are ultrasonic.
• Intensity: Depends on the magnitude of the vibrations of the body that produces them. A sound becomes stronger the greater its amplitude is. The sound intensity is measured in decibels (dB).
• Pitch: Quality of the sound that allows us to distinguish between two sounds of the same intensity and tone. There are always other sounds produced which accompany it; some of them are named harmonics.
• Sample Rate: The number of times per second that a sample is taken from an analogue sound signal to digitalize it.
• Channels: The number of points from which the sound is emitted. A mono sound has a single channel, a stereo sound has two channels, and a 5.1 sound has five channels.
• Sample Size: Indicates the amount of information (bits) that the sample occupies.

Advantages of Digital Audio

• Large store capacity of information, comparing prices, size, and capacity with analogue audio.
• By increasing the sample rate and the resolution in bits, we have an increase in quality.
• The possibility of making copies without losing quality.
• The durability of the original is enhanced.
• There is more variety of supports, and they are more comfortable.
• The possibility of fast and accurate finding of a fragment.
• The ever-smaller size of the devices.
• The infinite advantages of non-linear editing: undoing, copying, pasting, etc.
• It is easier to transmit, store, or handle.
• The digital signal is immune to noise and less sensitive than the analogue signal to interferences.
• A sound sample can be taken and change any of its parameters to generate a different sound.
• By the loss of a certain amount of information, the digital signal may be rebuilt.

Disadvantages of Digital Audio

• It requires a prior analogue-to-digital conversion and a later decoding at the reception time.
• When converting the continuous information into discrete, there is a loss of information.
• Each process we may perform with the signal will take longer the more quality it has.
• The increase of quality of the signal implies an increase in the amount of memory required.
• The transmission of the digital signal requires accurate synchronization between transmitter and receiver.
• If lossy compression is used, it will be impossible to rebuild the original signal.