science

Noise gate

Noise gate is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Noise gate rather than just read about it. In short: A noise gate or simply gate is an electronic device or software that is used to control the volume of an audio signal. Comparable to a limiter, which attenuates signals above a threshold, such as loud attacks from the start of musical notes, noise gates attenuate signals that register below the threshold.

Key takeaways

Noise gate belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Noise gate to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Noise gate from memory before moving on to harder problems.

Reference excerpt

A noise gate or simply gate is an electronic device or software that is used to control the volume of an audio signal. Comparable to a limiter, which attenuates signals above a threshold, such as loud attacks from the start of musical notes, noise gates attenuate signals that register below the threshold. However, noise gates attenuate signals by a fixed amount, known as the range. In its simplest form, a noise gate allows a main signal to pass through only when it is above a set threshold: the gate is open. If the signal falls below the threshold, no signal is allowed to pass (or the signal is substantially attenuated): the gate is closed. A noise gate is used when the level of the signal is above the level of the unwanted noise. The threshold is set above the level of the noise, and so when there is no main signal, the gate is closed. A common application is with electric guitar to remove hum and hiss noise caused by distortion effects units. A noise gate does not remove noise from the signal itself; when the gate is open, both the signal and the noise will pass through. Even though the signal and the unwanted noise are both present in open gate status, the noise is not as noticeable. The noise becomes most noticeable during periods where the main signal is not present, such as a bar of rest in a guitar solo. Gates typically feature attack, release, and hold settings and may feature a look-ahead function.

Controls and parameters

Noise gates have a threshold control to set the level at which the gate will open. More advanced noise gates have more features. The release control is used to define the length of time the gate takes to change from open to fully closed. It is the fade-out duration. A fast release abruptly cuts off the sound, whereas a slower release smoothly attenuates the signal from open to closed, resulting in a slow fade-out. If the release time is too short, a click can be heard when the gate re-opens. Release is the second-most common control to find on a gate, after threshold. The attack control is used to define the length of time the gate takes to change from closed to fully open. It is the fade-in duration. The hold control is used to define the length of time the gate will stay fully open after the signal falls below the threshold, and before the release period is commenced. The hold control is often set to ensure the gate does not close during short pauses between words or sentences in a speech signal. The range control is used to set the amount of attenuation to be applied to the signal when the gate is closed. Often, there will be complete attenuation, that is no signal will pass when the gate is closed. In some circumstances, complete attenuation is not desired, and the range can be changed. Advanced gates have an external sidechain. This is an additional input that allows the gate to be triggered by another audio signal. A variation of a sidechained noise gate used in electronic music production is a trancegate or just simply gate, where the noise gate is not controlled by an audio signal but a preprogrammed pattern, resulting in a precisely controlled chopping of a sustained sound. Noise gates often implement hysteresis, that is, they have two thresholds: one to open the gate and another, set a few dB below, to close the gate. This means that once a signal has dropped below the close threshold, it has to rise to the open threshold for the gate to open, so that a signal that crosses over the close threshold regularly does not open the gate and cause chattering. A longer hold time also helps to avoid chattering, as described above.

Roles

The basic function of a noise gate is to eliminate sounds below a given threshold. Noise gates are commonly used in the recording studio and sound reinforcement. Rock musicians may also use small portable stompbox units to control unwanted noise from their guitar amplification systems. Band-limited noise gates are also used to eliminate background noise from audio recordings by eliminating frequency bands that contain only static.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Noise gate

Start with the simplest possible case. Write down what Noise gate claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Noise gate before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Noise gate ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Noise gate

In research: Noise gate appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Noise gate in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Noise gate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Audio effects, Dynamics processing, Noise reduction, so understanding it makes those chapters shorter.
In everyday life: Look for Noise gate outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Noise gate in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Noise gate means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Noise gate out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Noise gate in simple terms?

Why does Noise gate matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Noise gate?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Noise gate.