While decibel reduction must adhere to a rigid set of standards, manufacturers can make all kinds of claims about audio quality and clarity. Music, conversation, environmental ambience and so on will take a hit regardless, but the impact varies between brands – some do a much better job at retaining audio quality than others.
We teamed up with the National Acoustic Laboratories (NAL) and the HEARing Cooperative Research Centre (co-founders of HEARsmart), to test manufacturer's claims.
In this article:
NAL conducts research in the areas of hearing assessment, hearing loss prevention and hearing rehabilitation, using on-site laboratories, high-end hearing equipment and volunteer participants. The experts at NAL test:
- decibel reduction claims on the box (attenuation tests), and
- real-world scenarios where filtered earplugs are typically worn (field tests).
Overall score and weighting in each category are determined by CHOICE.
Experts at NAL conduct two tests:
- A controlled environment test to determine the effective decibel reduction. This effectively checks the claims made on the box by manufacturers. The results are called an attenuation score.
- A field test, to assess other aspects important to the user such as sound quality, conversation clarity and comfort.
Filtered earplugs reduce volume by the number presented on the package, they do not drop decibels to that amount. For example, earplugs rated at 12dB will drop the volume in a 100dB environment (such as a concert or club) to 88dB. This number is called an attenuation value, which is presented on the package as a Noise Reduction Rating (NRR), or Single Number Rating (SNR). You can read about these international ratings in our filtered earplugs buying guide.
Australia does have a standard that applies to all earplugs (AS/NZS 1270) which is displayed as an SLC80 rating *(Sound level conversion), but manufacturers aren't required to put this attenuation value on the packet (unless they wish to demonstrate compliance with the standard). NAL's attenuation test is based on the AS/NZS1270 standard and displayed as an SLC80 rating.
SLC80 is the testing regime set out by the Australian standard. It requires that test subjects fit earplugs based on package instructions (without professional assistance) to determine their effectiveness in the hands of the average person. This means there's lots of variation in the results, and testers apply a correction to ensure that the stated degree of noise reduction is obtained on 80% of occasions. In other words, 80% of users should experience the stated SLC80 decibel reduction.
Earbuds are assessed in a variable acoustic room using 100 untrained participants, to establish an SLC80 rating. The level of reverb is adjusted to adhere to the AS/NZS 1270 standard. The test procedure is implemented using a computer equipped with signal acquisition and generation hardware and software that automates all signal presentations and collects and compiles the data.
The attenuation of a hearing protector is determined by measuring each subject's hearing thresholds with and without a hearing protector fitted. The difference between these two thresholds determines the 'real-ear attenuation' of the device. This procedure is repeated for seven test frequencies at each octave from 125Hz to 8kHz.
Real-ear attenuation of each device is calculated by subtracting the open-ear reference thresholds from the occluded-ear thresholds at each frequency. Results vary, due to the requirement that participants do not receive professional assistance when inserting the earplugs.
Single number rating (SNR)
In addition to SLC80
, NAL also calculates an SNR in accordance with ISO 4869-5, although we note that testing was conducted in accordance with the requirements of AS/NZS 1270 only. The SNR rating is comparable to SLC80
in that it also uses the real-ear attenuation threshold method but there are differences in the test procedures and calculation methods.
Fifty-three subjects provided data for the field trial. Each participant was allocated two different earplugs, and asked to wear them at music venues and other locations of their choice over several weeks. Subjects ranged in age from 19 to 48; they were 22 females, 27 males, and 4 respondents indicated they were of indeterminate/intersex/unspecified gender. Most participants had worn earplugs or earmuffs previously, with 15 participants reporting that they frequently or almost always wore earplugs at music venues.
Prior to conducting the field trial, subjects were asked to attend a briefing with a member of the research team. At the meeting, subjects were provided with two sets of earplugs (including instructions and different size options where applicable). The researcher showed each subject how to properly fit the earplugs, and discussed possible venues where the earplugs might be worn. At weekly intervals thereafter subjects were asked to provide feedback on their experience with the earplugs during the preceding week
- Music and conversation quality: Participants used a scale from 1 to 7 to rate the quality of the music while wearing earplugs. Of the 22 earplugs, four scored 5.5 or more indicating a minimal effect of the earplugs on quality of music. The same scale was used when asking about the effect of the earplugs on conversation. Here, there were only three earplugs that scored 5.5 or more, indicating that these earplugs did not interfere with conversation.
- Comfort, fit and ease of handling: Subjects were asked to use a 5-point scale to indicate how they rated the earplugs in terms of comfort, fit, discreetness, ease of handling, and overall appearance.
- Movement: Participants were asked to indicate whether the earplugs interfered with dancing (did they move or fall out during periods of rigorous movement?).
We give each pair of earplugs a CHOICE test score so you can see at a glance which are the best and worst, plus how each model compares for music quality, conversation quality, comfort and features. You can make your own assessment on how important you consider each area of testing, however we've weighted the scores accordingly:
- Music quality score 25%
- Conversation quality score 25%
- Comfort and fit score 25%
- Movement score 20%
- Ease of handling score 5%
Note that NAL's tested SLC80
and SNR results do not contribute to the overall score.
If you want to know which earplugs we rate the best, read our latest review. For an introduction and extra information on the products, read our filtered earplugs buying guide.