CEDIA/CTA-RP22 explained: the four levels and their targets

What it is

The full title is the CEDIA/CTA‑RP22 Immersive Audio Design Recommended Practice. It is published by CEDIA, the association for the home technology industry, together with the Consumer Technology Association. The current version is 1.2, from September 2023, and CEDIA makes it available free of charge.

RP22 covers private rooms with at least five channels plus subwoofers, playing consumer formats. It replaced an earlier CEDIA/CTA document that covered reference-grade rooms only, so it now applies to a family media room as well as a dedicated cinema.

Four levels of performance

Rather than a pass or a fail, RP22 describes four levels. Each is a complete set of targets, and the levels are recommendations, not requirements.

Level 1The minimum for conveying the basic intent of the soundtrack.
Level 2Conveys that intent more accurately.
Level 3Meets or exceeds reference commercial cinema.
Level 4The highest performance achievable on every parameter.

The targets are grouped under three headings: spatial resolution (how many loudspeakers, and where), dynamics (how loud, and how quiet the room is) and timbre (how even the sound is across the frequency range and from seat to seat). A room reaches a level only when every target for that level is met, at the reference seat and at the seat next to it.

The key targets

Parameter	Level 1	Level 2	Level 3	Level 4
Screen channels, maximum level	99 dB	102 dB	105 dB	108 dB
Surround and height channels, maximum level	96 dB	99 dB	102 dB	105 dB
LFE, all subwoofers combined	109 dB	112 dB	115 dB	118 dB
Bass extension (−3 dB, in room)	35 Hz	30 Hz	20 Hz	18 Hz
Background noise, maximum	NCB 35	NCB 26	NCB 22	NCB 18
Screen channels, seat-to-seat variation	±5 dB	±3 dB	±1.5 dB	±1.5 dB
Minimum number of loudspeakers	5	11	15*	15*

Minimum values. Levels are the SPL capability in dB SPL, C-weighted, at the reference seating position after calibration, without clipping. *13 for Auro-3D rooms. RP22 also gives recommended values above each minimum. Seat-to-seat variation for screen channels is measured from 500 Hz to 16 kHz. Source: CEDIA/CTA‑RP22 v1.2 (2023), Table A.1.

For context, the SMPTE commercial cinema standard sets peak capability at 105 dB, surrounds 102 dB and the LFE channel 115 dB. Those are the Level 3 minimums, which is why Level 3 is described as matching reference commercial cinema.

It rates rooms, not loudspeakers

Every RP22 target is measured at the seats of a finished room. The level a cinema reaches depends on the loudspeakers, but also on the amplifiers, the room’s size and construction, the acoustic treatment, the layout and the calibration. There is no RP22 certification for products: a loudspeaker cannot be “Level 3” on its own, but a room built around it can be.

What a loudspeaker contributes is the ability to reach the level targets at a given distance without strain, and to cover the seats evenly. That is what a designer needs from a loudspeaker’s published data.

Baffle walls

RP22 recommends that conventional box loudspeakers are either built into a baffle wall or placed more than a metre in front of the wall. Baffle mounting smooths the low-frequency response and raises output below about 300 Hz. It only works if it is done properly:

The baffle should be stiff, heavy and well damped, so that it does not vibrate and radiate sound itself.
The loudspeakers should not touch the baffle directly: they sit on isolating pads, are gasketed in, and the cut-outs are oversized.
Loudspeakers not designed for baffle mounting need equalisation to remove the extra bass it creates.

Where a proper baffle wall is not possible, RP22 advises leaving it out and using absorption around the screen loudspeakers instead. Every AMP loudspeaker is designed for baffle-wall installation.

From specifications to a prediction

RP22 shows how to use manufacturers’ specifications to predict a system’s performance before anything is installed. The simplest case is peak level: sensitivity, amplifier power and distance to the seat give an estimate you can compare with the targets above.

When comparing loudspeakers, read maximum SPL figures with care. Manufacturers use different conventions: some add 6 dB for peaks and others 3 dB, and some add a further 6 dB for baffle-wall mounting to a sensitivity figure that already includes it. The same loudspeaker can be quoted several decibels apart, so the fairest comparison is the level each one delivers at your seats.

Try it with the calculator.

Checking the result

RP22 sets the targets; a companion document, CEDIA RP‑32 (Audio System Measurement and Verification), sets out how to measure a finished system against them. Ask for the measurements when a room is handed over.

How AMP uses RP22

Every AMP loudspeaker is designed to the performance targets of RP22: the Cinema Pro 8 for the screen channels, the Cinema Pro 6 for the surrounds and heights, and the Cinema Pro 18S subwoofers in pairs or fours. Each model’s specifications give its maximum output and the RP22 level it reaches at a stated distance, so designers can plan a room around it: the Cinema Pro 8 reaches the Level 3 screen level at 4 m through a screen, and four Cinema Pro 18S reach the Level 3 LFE target down to 20 Hz.

Source: CEDIA/CTA‑RP22 Immersive Audio Design Recommended Practice, v1.2, September 2023. This page summarises the document; refer to it for the full set of 21 parameters and their definitions.

RP22, explained.