engineering

NOS stereo technique

NOS stereo technique is a engineering 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 NOS stereo technique rather than just read about it. In short: The Nederlandse Omroep Stichting (NOS) stereo technique is a method of capturing stereo sound. The Nederlandse Omroep Stichting (English: Dutch Broadcast Foundation) found a stereo main microphone system by a number of practical attempts in the 1960s.

Key takeaways

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

Reference excerpt

The Nederlandse Omroep Stichting (NOS) stereo technique is a method of capturing stereo sound. The Nederlandse Omroep Stichting (English: Dutch Broadcast Foundation) found a stereo main microphone system by a number of practical attempts in the 1960s. This system resulted in a quite even distribution of the phantom sources (hearing event direction) on the stereo loudspeaker base, with two small cardioid characteristic microphones, and a recording angle of the microphone system of ±40.5° = 81°. This system got empirical an axle angle of α = ±45° = 90° and a microphone distance (microphone basis) of a = 30 cm. With this system are frequency-independent level differences effective and time of arrival differences working together in the same direction as interchannel signals (interchannel loudspeaker signals). This technique leads to a realistic stereo effect and has a reasonable mono-compatibility. These interchannel differences have nothing to do with interaural differences which come only from artificial head recordings. Even the spacing of a = 30 cm has nothing to do with human ear distance, because a useful microphone system for a set of stereo loudspeakers should be developed and not for ear phones. This recording technology is called mixed stereo or equivalence stereo. Usually this special microphone system must be built up from two single small diaphragm microphones. One should not use double diaphragm microphones because of the produced unbalanced directional characteristics and the larger phase responses. It appears advisable to experiment with the two parameters the axle angle α and the microphone basis a to which there are practical microphone mounting devices. A similar technique is known as the ORTF stereo technique, devised by the French ORTF. With this technique is the angle between the microphone axes α = ± 55° = 110° and the distance between the cardioid microphones (microphone basis) is in this case a = 17 cm and gives a total recording angle of 96°. The choice between one and the other depends on the recording angle of the microphone system and not on the distance to and the width of the sound source, the orchestra angle.

See also Blumlein pair, 90° figure-of-eight ORTF stereo technique, 2 cardioids

External links Visualization NOS Stereo Microphone System - Cardioid/Cardioid - 90° 30 cm Equivalence Stereo - SRA Recording angle

Illustrations

Worked examples

Example 1 — a first encounter with NOS stereo technique

Start with the simplest possible case. Write down what NOS stereo technique claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, 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 NOS stereo technique 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 NOS stereo technique 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 NOS stereo technique

In research: NOS stereo technique appears in engineering 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 NOS stereo technique 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: NOS stereo technique is common in secondary-school and first-year university syllabi. It links to neighbouring topics Audio engineering, Dutch inventions, Microphone practices, so understanding it makes those chapters shorter.
In everyday life: Look for NOS stereo technique 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 NOS stereo technique in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NOS stereo technique 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 NOS stereo technique out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NOS stereo technique in simple terms?

Why does NOS stereo technique matter?

Because it connects several engineering 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 NOS stereo technique?

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 NOS stereo technique.