What do the numbers in 7.1.4 mean?
Speakers at ear level, then LFE channels, then speakers overhead. 7.1.4 is seven, one and four.
The dotted names are industry shorthand. IAMF spells them out: surround channels, then LFE channels, then height channels.
The ITU’s own names are letters, from System A to System J. Each comes with a count of speakers above, at ear level and below.
A few everyday layouts have no ITU letter. 7.1.2 and 9.1.6 are two of them.
The largest layouts add a fourth number, for speakers below ear level (section 5).
| Layout | ITU name | What it adds |
|---|---|---|
| Stereo | System A, 0+2+0 | Two speakers in front. |
| 5.1 | System B, 0+5+0 | A centre, two surrounds and an LFE. |
| 5.1.2 | System C, 2+5+0 | Two overhead, towards the front. |
| 5.1.4 | System D, 4+5+0 | Four overhead, front and back. |
| 7.1 | System I, 0+7+0 | Side and rear surrounds, in place of two. |
| 7.1.4 | System J, 4+7+0 | 7.1 with four overhead. |
| 9.1.6 | None | 7.1.4 with two wides and two more overhead. |
| 22.2 | System H, 9+10+3 | Three layers and two LFEs, built for 8K television (section 5). |
SoRead a layout name as ear level, LFE, overhead. The ITU counts overhead first and leaves the LFE out.
Where do the ear-level speakers go?
Left and right at 30° either side. A centre straight ahead. Surrounds at the sides, and in 7.1, behind you too.
| Speaker | Stereo | 5.1 | 7.1 and 7.1.4 |
|---|---|---|---|
| Left, right | 30° | 30° | 30° to 45° |
| Centre | None | 0° | 0° |
| Side surrounds | None | 100° to 120° | 85° to 110° |
| Rear surrounds | None | None | 120° to 150° |
Stereo is the familiar triangle: the speakers span 60°, with you at the point. The ITU says the same.
In 5.1, the surrounds can sit anywhere from 100° to 120°. The ITU says the exact spot is not critical.
7.1 splits them in two: sides at about 90°, rears at about 135°. Their ranges don’t overlap.
Angles count from straight ahead, mirrored left and right. ITU documents write left angles as positive, which some tools reverse.
SoEach speaker has a range, not a single spot. Get every speaker inside its range, fronts at ear height, and pairs mirrored.
Where do the height speakers go?
Above the front and rear speakers, between 30° and 55° up from your ears.
| Speaker | Around you | Up |
|---|---|---|
| Top front, in 5.1.2, 5.1.4 and 7.1.4 | 30° to 45° | 30° to 55° |
| Top back, in 5.1.4 | 100° to 135° | 30° to 55° |
| Top back, in 7.1.4 | 100° to 150° | 30° to 55° |
The heights are a second ring, smaller and higher than the first. In 7.1.4 there are four: two in front, two behind.
The range is wide, so a real ceiling can usually meet it. Orbit’s reference layout uses 45°, near the middle.
5.1.2 has only the front pair. That is the ITU’s System C. A 5.1.2 with heights at the sides is a different layout.
SoMount the heights 30° to 55° up, above the front and back. Measure the angle from your ears.
What do 9.1.6 and bigger add?
9.1.6 is 7.1.4 plus two wides at ear level and two more speakers overhead, at the sides.
The wides fill the gap between the fronts and the sides, at about 60°. The top sides fill the gap overhead, at 90°.
9.1.6 is not one of the ITU’s systems. Its angles come from ITU-R BS.2094, which lists positions but no ranges.
IAMF describes 9.1.6 as part of the ITU’s largest layout, System H, better known as 22.2 (section 5).
Bigger is not always more useful. The ITU’s emission profile accepts no speaker bed larger than 7.1.4, short of 22.2.
So9.1.6 has no ITU ranges, so treat its angles as targets. Bigger rooms, up to 22.2, are their own ITU systems.
What about speakers below ear level?
The largest layouts add a third ring, below your ears. Their names gain a fourth number, which counts those speakers.
Most layouts are a dome: ear level and overhead. A few add speakers below, so sound can come from underneath too.
IAMF names these with four numbers. Read them as ear level, LFE, overhead, then below.
| Layout | ITU name | What it is |
|---|---|---|
| 7.1.5.4 | None | 7.1.4 plus one speaker straight overhead and four below, front and back. IAMF builds it on System J. |
| 10.2.9.3 | System H, 9+10+3 | The layout usually called 22.2. Ten at ear level, two LFEs, nine overhead and three below, in front. |
| No common name | System E, 4+5+1 | 5.1.4 with one speaker below. |
IAMF doesn’t define the fourth number. Its own reference software does label it: 7.1.5.4 is stored as 7 surround, 5 height and 4 bottom.
So read a fourth number as speakers below ear level. It is common usage, not yet a standard’s definition.
What is 22.2, and who uses it?
22.2 is NHK’s layout for 8K television, which NHK calls Super Hi-Vision. It is 24 channels in three layers.
Nine speakers sit overhead, including one straight above you. Ten sit at ear level, and three sit low, across the front. Two LFEs complete it.
The low three sit below the screen, 15° to 30° below ear level. With the layers above, they let sound sit anywhere across a large picture.
NHK’s own mixing puts water and ground sounds there, such as the sea, or the ground in a shot from above.
It is a standard three times over: SMPTE ST 2036-2 in 2008, ARIB STD-B59 in 2014, and the ITU’s System H.
NHK’s 8K satellite service has carried it since 1 December 2018, with a stereo version alongside. NHK has also tested it with MPEG-H 3D Audio.
We found no other broadcaster, and no streaming service, delivering 22.2. 9.1.6 is a part of it, with the bottom layer and some speakers left out.
SoA fourth number means speakers below you. Few rooms have them, so check the delivery spec before you mix for one.
Where does the LFE go?
Wherever it sounds best. The ITU gives the LFE no set position in 5.1, 7.1 or 7.1.4.
Low frequencies are hard to place by ear. So one subwoofer can serve a whole layout.
The LFE carries up to 120 Hz. By the ITU’s rule, it is recorded 10 dB down and played back 10 dB up, within its band.
Music formats often use no offset. Check your delivery spec before you calibrate.
The ITU is clear about its role:
“The LFE channel must therefore be considered as, at most, an enhancement, and definitely not as an essential part of the mix.”
ITU-R BS.775-4, annex 7
The LFE is not bass management. Bass management sends the low end of every channel to your subwoofer. That is a monitoring choice, not part of the mix.
SoPlace the subwoofer where the room sounds smoothest. Treat the LFE as extra low end, never as part of the mix you need.
Why is 7.1.4 the reference?
No standard says so. But the tools you deliver with all centre on it, so it has become the common bus.
Look at where the work ends up, and 7.1.4 keeps appearing.
- Apple’s Logic ProApple recommends a 7.1.4 speaker setup for immersive mixing. Logic’s renderer always outputs 7.1.4, even when you monitor on fewer speakers.
- The ITU’s emission profileITU-R BS.2168 accepts beds up to 7.1.4, then jumps to 22.2. 9.1.6 is not on its list.
- IAMF7.1.4 is the largest of IAMF’s scalable layouts. Some smaller ones are defined as parts of it.
Orbit works the same way. Its monitoring and metering all come from one 7.1.4 bus. Its documentation puts it like this:
“Binaural, Apple Spatial Audio, stereo fold-down and loudness are always derived from Orbit’s internal 7.1.4 bus …”
Orbit documentation, Monitoring
One bus means one truth. Your headphone mix, your stereo fold-down and your loudness meter all hear the same thing.
SoMix and check on 7.1.4, in a room or on headphones from a 7.1.4 bus. Your other monitoring is derived from it.
My room doesn’t match. Now what?
Get each speaker inside its range, keep pairs mirrored, then fix distance and level electronically.
- A speaker can’t reach its exact angle.
- Anywhere inside its range is fine. That is what the ranges are for.
- The two sides of the room differ.
- Pairs more than 45° off-centre, like the sides and rears, may be up to 10° out of mirror. Pairs at 45° or less should match exactly. Every speaker stays inside its range.
- Some speakers are nearer than others.
- Delay the nearer ones, so every speaker arrives at your head at the same time. Surrounds shouldn’t sit closer than the fronts without it.
- Some speakers sound louder.
- Play pink noise through each speaker in turn, and set them to the same level at your seat. The ITU does this for its listening tests.
- The ceiling is too low or too high.
- Anywhere from 30° to 55° up works. Measure the angle from your ears, not the height from the floor.
SoAngles first, then mirror the pairs. Then delay the nearer speakers, and match every speaker’s level with pink noise.
How do I describe my own room?
Write down where each speaker really is. The ITU says those positions should be stored as metadata.
BS.2051 expects real rooms to differ, and says the positions used should be stored as metadata. A description of the room does that.
OSLSAn open file format, from us, that describes a speaker rig: where each speaker is, and its ITU label. Build one in the 3D designer at osls.io.
OrbitImport an OSLS file and Orbit outputs to your rig, up to 64 channels. Binaural and stereo still come from its 7.1.4 bus.
An OSLS file describes the rig and nothing more. It doesn’t render, and it doesn’t decide which output feeds which speaker.
SoMeasure your room once and describe it in an OSLS file. Then monitor on the speakers you really have.
Five questions before you go
Question 1 of 5Glossary
- 7.1.4, 9.1.6
- Industry shorthand for a layout: speakers at ear level, then LFE channels, then speakers overhead.
- 22.2
- NHK’s 24-channel layout for 8K television: nine overhead, ten at ear level, three low at the front, two LFEs. The ITU’s System H.
- System letter
- The ITU’s name for a layout in ITU-R BS.2051, from System A (stereo) to System J (7.1.4).
- 4+7+0
- The ITU’s count of speakers above, at ear level and below. It leaves the LFE out.
- Azimuth
- The angle around you, from straight ahead. In ITU documents, positive angles are to the left.
- Elevation
- The angle up from ear level. 90° is straight overhead.
- LFE
- The low-frequency effects channel: the “.1”. It carries up to 120 Hz, and has no set position in 5.1, 7.1 or 7.1.4.
- Bass management
- Sending the low end of every channel to a subwoofer. A monitoring choice, separate from the LFE channel.
- Bottom layer
- Speakers below ear level. A fourth number in a layout name, as in 7.1.5.4, counts them.
- Wides
- A pair of ear-level speakers between the fronts and the sides, at about 60° in 9.1.6.
- Reference bus
- One layout that every mix is rendered to first, so every other output is derived from the same thing.
- OSLS
- An open file format from South Loop Studios that describes a speaker rig: where each speaker is, and what it is.
Further reading
ITU-R BS.2051 sets the layouts and their ranges, and BS.775 covers stereo and 5.1. Both are free to download.
- ITU-R BS.2051-3, “Advanced sound system for programme production,” 2022. itu.int
- ITU-R BS.775-4, “Multichannel stereophonic sound system with and without accompanying picture,” 2022. itu.int
- ITU-R BS.2094-2, “Common definitions for the audio definition model,” 2025. itu.int
- ITU-R BS.2168-0, “Audio definition model and serial representation of audio definition model profile for advanced sound systems emission,” 2025. itu.int
- ITU-R BS.1116-3, “Methods for the subjective assessment of small impairments in audio systems,” 2015. itu.int
- Alliance for Open Media, “Immersive Audio Model and Formats,” v2.0.0, 24 August 2026. aomediacodec.github.io/iamf
- Apple, Logic Pro User Guide for Mac: monitoring formats, and surround formats in an immersive mix. support.apple.com · support.apple.com
- Orbit documentation, “Monitoring,” “Speaker Configuration” and “OSLS.” docs.orbitspatial.io
- South Loop Studios, OSLS: specification and SDK, Apache 2.0. github.com/South-Loop-Studios/osls · Designer: osls.io
Written by the people who make Orbit.