Difference Between Noise and Signal

In the world of communication, there are two types of data that we encounter frequently, noise, and signal. These two terms are often used interchangeably, but they are not the same. Noise refers to any unwanted or random interference that occurs in a signal, while a signal is the desired information being transmitted. In this essay, we will discuss the differences between noise and signal in detail.

What is Noise?

Noise is described as any unwanted sound that is judged as overly loud and disruptive to hear. From a physics point of view, noise is regarded as indistinguishable from the signal as both are vibrations that happen through a medium such as air or water. The main difference between the two is realized when the brain receives and perceives a sound and categorizes it based on the surrounding and activities of the time.

Different Types of Noises

Noise can be categorized in any sound, size, and shape. It is part of our day-to-day lives, but before one can accurately measure it, they need to know its various types. The types are as listed below −

  • Continuous noise − This is a noise produced in a continuous flow, for example, by a machine that runs without interruption.

  • Intermittent noise − This category refers to the noise whose levels keep increasing and decreasing. This noise is produced by such things like aircraft overhead, factory equipment operating in cycles, or trains passing by some place.

  • Impulsive noise − An impulsive noise is commonly associated with the construction and demolition fields. It is usually as a result of sudden bursts and can startle anyone nearby due to its fast and surprising nature.

  • Low-frequency noise − A low-frequency noise is associated with our daily soundscape. Such noise could be from power plants humming in the background or large diesel engines roaring in low frequencies.

What is Signal?

A signal can take different forms ranging from movements to actions, motion, and sound. In this case, we look for the sound meaning of a signal.

From a physics standpoint, a signal is any electromagnetic field or electric current that is used to convey data from one point to another. When it comes to deeper communication systems, electrical engineering, and signal processing, it is defined as a function used to convey information about the attributes or behavior of some phenomenon. It can also be taken to mean any observable change in any quantifiable entity.

Different Types of Signals

Signals are categorized into two, namely analog and digital signals. The main types are quantified using various signals. The types are as explained below −

  • Motion − When an object makes a motion, it can be considered to be a signal. It can also be monitored using various sensors to provide signals.

  • Sound − A sound is a vibration through a medium such as air. It associates a pressure value to values of time and three space coordinates. Usually, for sound to qualify to be a signal, it has to be converted into an electrical signal by a microphone.

  • Images − An image or picture consists of a color signal or brightness. The object appears as a reflected or emitted electromagnetic wave, a form of electronic signal.

  • Other signal types are videos and biological membrane potentials.

Differences: Noise and Signal

One key difference between noise and signal is that a signal is intentional and carries meaningful information, while noise is unintentional and does not carry any information. In other words, a signal is created to transmit a specific message, while noise is an unwanted addition that can interfere with the message. A signal is usually a specific frequency or pattern that can be decoded, while noise is unpredictable and random.

Another difference between signal and noise is that the signal is typically stronger than the noise. The signal needs to be strong enough to overcome any interference that may be present. If the signal is weak, the noise can overpower it, making it difficult to decode the message. Therefore, a strong signal is essential to ensure that the message is transmitted accurately.

In addition, signal and noise can be measured using different parameters. Signal is typically measured in terms of amplitude, frequency, and phase, while noise is measured in terms of signal-to-noise ratio (SNR). SNR is the ratio of the power of the signal to the power of the noise. A higher SNR indicates that the signal is stronger than the noise, while a lower SNR indicates that the noise is stronger than the signal.

Furthermore, signal and noise can affect the accuracy and reliability of the message being transmitted. Noise can distort or corrupt the signal, leading to errors in the received message. To minimize the impact of noise on the signal, various techniques such as error-correcting codes, filtering, and modulation are used. These techniques can help improve the accuracy and reliability of the message being transmitted.

The following table highlights the major differences between Noise and Signal −





Noise, on the other hand, is any unwanted sound or effect on signals.

A signal is an information carrier which is a space and time-varying quantity and is used to send the information it carries.


Noise is the unwanted one that should be eliminated.

A signal is usually the wanted part.


The signal to noise ratio of noise is low.

A signal qualifies to be of high quality since its signal to noise ratio is high.


In conclusion, noise and signal are two critical concepts in communication systems. While both are related to the transmission of information, they are not the same. Signal is the desired information being transmitted, while noise is any unwanted or random interference that can affect the quality of the signal.

A strong signal is essential to overcome any interference that may be present, and various techniques are used to minimize the impact of noise on the signal. Understanding the differences between noise and signal is crucial in designing and implementing effective communication systems.

Updated on: 19-Apr-2023


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