Processing of audio signals is one of the most important and widely used applications of digital signals processing. It is being used in many fields such as communication, broadcasting audio signals for radios, television etc. It primarily includes analysis of audio signals that fall in the human hearing frequency by mathematical. The audio signals that fall in the human auditory range depend both on physical and psychological factors. A separate branch has been introduced to study the same and is called psychoacoustics.
Wherever signals are concerned, one has to deal with two different viz. digital and analogue types. The techniques that are used to deal with these two types of audio signals are different. In analogue audio signals, the pressure transformations are usually represented electrically in the form of voltage levels.
The digital representation of audio signals is usually in the form of binary digits used to represent the pressure variations. One should note that the digital representation of the audio signals is used only to facilitate the use of computers in the same analysis. In the real world, these signals are continuous or analogous in nature. However, as human ears’ capacity is limited, digital representation of the same is possible provided that the sampling rate of the audio signals is high. Also, noise is always present with the audio signals that are required. Thus, quantisation of the audio signals does not result in the loss of a large amount of actual information.
The generated audio is often converted into other forms to transfer it at greater rates and with less loss. For example, in optical fibres, the sound is converted into light energy and is then transferred to the desired location. Such conversion of audio into other forms is a part of audio processing as well.
Other applications of audio processing include broadcasting of sound, enhancement of audio etc. Before an audio signal is broadcasted, a large amount of processing is done on it. This includes mixing, different steps in recording, noise reduction etc. From the processing that is carried out, later on, various audio formats are generated depending on the method used for audio encoding, the amount of original audio that is retained. Then, when the audio signal is received on devices at your homes or other places, some amount of processing is done on it once again. This may include amplification of the audio to increase its loudness, noise reduction once again, and add various effects to it such as surround sound. To obtain the surround sound effect, two audio signals are generated from the original one and are made out of phase with each other.
Apart from these, the other applications of audio processing are innumerable. Thus, it will always be among the most popular fields in which signal processing is applied as it finds its use in some of the most popular devices such as television, cell phones etc.