ASTM E596-96 Explained: What It Tests and What Replaced It
Open a sound booth data sheet and you’ll often find a NIC rating. ASTM E596-96 is the laboratory method that produces it, measuring the noise reduction of a complete sound-isolating enclosure in a reverberation room.
We build reusable temporary walls at STARC Systems for renovations in occupied hospitals and airports. For this guide, we read the ASTM listings for the 1996 and 2022 editions and a 2023 conference study of working booths.
What Is ASTM E596-96?
ASTM E596-96 is the 1996 edition of ASTM’s lab test for enclosures built to isolate sound, a method ASTM first approved back in 1977.
In the test, labs compare the sound pressure level in the reverberation room with the level inside the enclosure in each one-third octave band. The difference in each band is the noise reduction (NR), and ASTM E413 rolls those bands into a single number, the noise isolation class (NIC).
The “-96” is easy to misread. ASTM tags each standard with a hyphen and the last two digits of the year it was accepted or last revised, so “-96” means the last substantive revision landed in 1996. A year in parentheses, like (2009) or (2016) on older listings, marks a reapproval since then.
The current edition is E596-22, approved October 1, 2022, so the ASTM store now lists E596-22 as active and E596-96(2016) as historical. If a spec on your desk still cites E596-96, ask which edition the lab actually followed.
How the ASTM E596 Test Works
The lab places the finished enclosure in a reverberation room of at least 200 m³ effective volume and mounts it on the floor the way it sits in normal use.
Before the measurement, any built-in ventilation runs for 10 minutes and is switched off, and every door and access panel is opened and closed at least 10 times, so the result reflects how the enclosure seals after real handling.
A loudspeaker outside the enclosure, kept out of its direct field and usually aimed into a room corner, plays bands of random noise. Microphones read one-third octave band levels at six or more points in the room and four or more inside the enclosure.
The noise reduction in each band is the difference between the average level outside the enclosure and the average level inside.
Background noise inside has to sit at least 10 dB below the test signal; between 5 and 10 dB the lab corrects for it, and under 5 dB the measurement is only a lower-limit estimate that the report has to flag.
The standard sets tighter precision at higher frequencies, within 1 dB from 315 to 4000 Hz, and it expects a given enclosure to produce the same result from one lab to the next.
Parameter | Requirement |
Reverberation room | Effective volume (room minus enclosure) not less than 200 m³ |
Test signal | Bands of random noise, one-third octave bands 125–4000 Hz (may extend higher) |
Sound source | Outside the enclosure, kept out of its direct field |
Microphone positions | At least 6 in the room, at least 4 inside the enclosure |
Instrumentation | Type 1 sound level meter with a one-third-octave filter set (ANSI S1.4 / S1.11) |
Background noise | At least 10 dB below the test signal; 5–10 dB corrected; under 5 dB flagged as a lower-limit estimate only |
Result | Noise reduction per band, converted to a single NIC by ASTM E413 |
What an ASTM E596 Test Reports
Booth makers publish E596 results as a table and cite the numbers to compare one booth with another. A typical audiometric booth table reports noise reduction from outside to inside for octave bands from 125 Hz to 8000 Hz, with the NIC alongside.
Read the band values before the NIC. A single rating hides the frequencies where an enclosure leaks. If your noise sits low, check the 125 Hz and 250 Hz columns first.
Door seams and vents tend to leak at the high end instead, and because NIC is figured only from the 125–4000 Hz bands, a high-frequency leak can leave the single number looking better than the booth performs. A test on the finished enclosure records the combined effect of every leak, high bands included.
ASTM E596 Limitations
ASTM E596 produces a clean NIC in the lab, but three limits decide where that number applies.
ASTM E596-96 provides generic enclosure data for any sound source, so it never singles out speech. A 2023 conference study judged ISO 23351-1 the better fit for phone booths, where speech is the main sound source.
It reads in one direction. The test measures noise entering an enclosure, so a NIC rates protection from outside noise. Speech escaping a booth needs a different rating.
The test also runs in a laboratory. Your jobsite brings its own room and background noise, so use a lab NIC to rank enclosures against each other.
ASTM E596 vs ISO 23351-1
E596 rates the noise that gets in, and ISO 23351-1 rates the speech that gets out. The ISO method places a loudspeaker inside the booth and measures sound power in a test room, first with the booth absent and then with it in place.
Octave-band differences from 125 Hz to 8000 Hz become one number, speech level reduction (DS,A), which expresses the drop in A-weighted sound power level of standard speech. The standard also defines booth classes from A+ to D.
The study’s authors ran four phone booths through both methods. Octave-band results from E596-96 estimated DS,A about 0.5 dB higher than the ISO values on average. Four booths is a small sample.
ASTM E596 vs ASTM E90 and STC
ASTM E90 rates a partition, and E596 rates an enclosure. A lab seals the E90 specimen into the opening between two reverberation rooms and measures how much sound reaches the receiving room.
Sound transmission loss comes out in one-third octave bands. ASTM E413 then fits a reference curve to the bands from 125 Hz to 4000 Hz and returns one number, the Sound Transmission Class (STC).
E90 covers panels and other space-dividing elements, which makes STC the rating for a temporary partition between a work zone and an occupied area.
Panel build and perimeter sealing both shape the STC, so the number only holds for the exact wall system the lab tested.
Who Uses ASTM E596
E596 covers any enclosure built to isolate a space from sound, so its results describe more than hearing booths. Audiometric and hearing-test booths are the clearest fit, which is why IAC Acoustics rates its 40a Series at a minimum of 25 dB at 125 Hz and 62 dB at 8000 Hz with E596 as the named test method.
Equipment and machinery enclosures fall under the same scope, and office phone booths and pods have been specced against it as well, though ISO 23351-1 fits speech-dominated spaces better.
Anyone who specifies or designs an enclosure can use the results three ways, according to the standard:
Ranking enclosures by NIC
Estimating the highest outside band levels that keep inside levels within set limits
Estimating inside band levels for given outside levels
ASTM E596-96 PDF Download
ASTM’s E596-96 page points to E596-22 as the current edition, sold through the ASTM store. To get the PDF:
Buy ASTM E596-22 from the ASTM store.
Sign in at astm.org.
Open My Digital Documents.
Read the PDF in ASTM’s web viewer.
Reseller catalogs still list the 2009 reapproval of E596-96, but ASTM has superseded or withdrawn it.
Check whether your employer or library holds an ASTM subscription. The free Reading Room covers only standards cited in U.S. regulations, and copies there show the edition the regulation names.
How to Choose a Sound Rating
Each test fits one kind of product, and the table below sorts them.
ASTM E596 | ASTM E90 | ISO 23351-1 | |
Tests | Enclosure | Partition | Booth |
Reports | NR and NIC | STC | DS,A |
Best for | Hearing-test booths | Temporary walls | Phone booths |
A patient corridor beside demolition calls for an E90 rating, and a hospital’s sound management plan sets the target.
Ask each vendor for the test standard and the configuration tested. Loose doors and penetrations let noise leak even when the panels perform well, so confirm the lab tested a full temporary construction enclosure.
ASTM E596-96 and STARC Temporary Walls
RealWall™, our flagship panel, is built 1 inch thick around a sound-attenuating foam core, with precision-sealed joints that close the seams. It cuts renovation noise by up to 50% under ASTM E90 (STC 21), which is why we recommend it for long-term, high-visibility jobs in airports and offices.
Sarasota-Bradenton International Airport put that to the test. With some 3.7 million passengers moving through its two-level terminal, airport officials replaced one escalator with two, which meant enclosing a 30-foot atrium.
Modular Wall Solutions, a subcontractor to GC DeAngelis Diamond, placed LiteBarrier™ panels over the existing tall wall and used RealWall for noise reduction and security. The first install ran from 10:00 PM to 7:00 AM, and passengers walked past the double doors with no idea crews were cutting structural slab on the other side.
When a renovation also carries fire-code requirements, FireblockWall™ carries STARC’s highest lab-tested sound number at STC 40.
A temporary wall also has to go up fast and move on, one of the tough jobsite challenges temporary walls solve. A two-person crew installs up to 100 linear feet of STARC wall in an hour with a single tool, and each panel can be reused more than 50 times, with break-even after 2 to 4 uses versus drywall.
Poly can cover a one-day partition; a renovation in a building that stays open needs panels that survive repeated reinstalls, and that is where STARC fits.
To undisrupt your next renovation, answer a few questions in the Wall Wizard to match a STARC system to your project, or request a quote and we’ll help you spec the right wall for the sound rating your job calls for.
Frequently Asked Questions
What is ASTM E596-96?
ASTM E596-96 is the 1996 edition of ASTM’s lab test for sound-isolating enclosures, first approved in 1977. Labs report noise reduction by one-third octave band and derive a single NIC.
Where can you download ASTM E596-96?
You can buy the current edition, ASTM E596-22, from the ASTM store. After checkout, you read the PDF in ASTM’s web viewer under My Digital Documents.
Is ASTM E596-96 still current?
No, ASTM E596-96 is no longer current. It’s a superseded edition. ASTM approved E596-22 on October 1, 2022, and the ASTM store lists E596-22 as active.
What does NIC mean in ASTM E596?
NIC stands for noise isolation class. ASTM E413 converts the band-by-band noise reduction from an E596 test into one number that ranks enclosures.
What does ASTM E stand for?
In ASTM designations, E stands for miscellaneous subjects, one of seven letter categories from A to G. E596 and E90 both carry it.
What is ASTM E-90?
ASTM E90 is the laboratory test method for airborne sound transmission loss of partitions such as walls, doors, windows, and panels. ASTM E413 converts the results into an STC.
Is ASTM E596 the same as ISO 23351-1?
No. ASTM E596 rates noise entering an enclosure, and ISO 23351-1 rates speech escaping a booth in octave bands from 125 to 8000 Hz.
