BS EN 50332 tests for headphones and earphones with portable music players

Prolonged exposure at high volume settings to the sound from headphones or earphones can damage a user’s hearing.

To minimise the risk of hearing impairment, a European standard has been issued which specifies test procedures for measuring the sound levels from the headphones and earphones of personal music players and similar consumer equipment. 

This standard, EN 50332, has two parts.  Part 1 covers “one package equipment”, where the headphones and the music player are supplied together as a unit.  Part 2 covers the matching of headphones and players which are sold separately. 

EN 50332:2013 Part 1

Measured programme simulation noise spectrum, with tolerance

EN 50332 Part 1 requires a specified test signal to be replayed from the device under test.  The test signal, or “programme simulation noise” is a pink noise signal which has been filtered to change the spectrum shape and then soft-clipped to reduce the crest factor.  The test signal is recorded or uploaded to the player at a specified level. 

The test signal is played from the player at the maximum volume setting and the sound levels from the attached headphones are measured using a Head and Torso Simulator or “HATS”.  At ISVR Consulting we use a Kemar manikin as our HATS.  Our Kemar conforms to International Standard IEC 60318-7 and is fitted with ear simulators with microphones at the eardrum positions.  The sound levels recorded at the manikin's eardrum microphones are converted to the equivalent free-field or diffuse field sound levels. The test is repeated five times with the headphones refitted before each test.

EN 50332:2013 Part2

EN 50332 Part 2 uses the same programme simulation test signal as Part 1.  When testing a player without headphones, the signal is replayed at the player’s maximum volume setting and the voltage at the player’s headphone socket is measured across a 32 ohm load.

The Kemar manikin

When testing headphones without a player, the test signal is replayed from a source through an amplifier to the headphones under test.  The headphones are placed on the HATS or manikin as in Part 1, and the sound level is measured.  The voltage required to produce a sound level of 94 dB(A) is measured. 

When a player producing 150 mV or less is combined with headphones which require 75 mV or more to produce a sound level of 94 dB(A), the sound level of the combination must be 100 dB(A) or less.

Sound level limits

The 2013 version of EN 50332 specifies a test method.  The actual limits are specified in other standards (EN 60065 or EN 60950-1). 

For “one package equipment” tested to EN 50332-1:

• If the maximum sound level is 85 dB(A) or less when tested according to EN 50332-1, the equipment does not require any specific safety features.
• At volume settings for which the sound level is greater than 85 dB(A), the user must be informed by a visual or audible signal, and must acknowledge the signal, before he or she can override the volme limit to allow replay at these settings. The warning has to acknowleged at regular  intervals. The equipment must default to a setting which gives less than 85 dB(A) when switched on.
• The sound level must, in any case, be 100 dB(A) or less at maximum volume.

For combinations of player and headphones not supplied as a package, tested to EN 50332-2.

• If the electrical output at the player's headphone socket is 27 mV or less when tested according to EN 50332-2, the equipment does not require any specific safety features or provision.
• At volume settings for which the output voltage is greater than 27 mV, the user must be informed by a visual or audible signal, and must acknowledge the signal, before he or she can override the volume limit to allow replay at these settings. The warning has to acknowleged at regular  intervals. The equipment must default to a setting which gives 27 mV or less when switched on.
• The output voltage at the player's headphone socket must, in any case, be 150 mV or less at maximum volume.
• For a sound level of 94 dB(A), the analogue input voltage to headphones or earphones must be 75 mV or less. 

Note that if a player produces 150 mV or less, and the headphones require 75 mv or more to produce 94 dB(A), the maximum sound level of the combination will be 100 dB(A). Also, if the palyer produces 27 mV or less, the maximum sound level from the headphoneswill be 85 dB(A) when replaying the test signal.

Labelling

“One package equipment” capable of generating more than 85 dB(A), or any player providing a headphone socket with more than 27 mV output, must be accompanied by a warning either on the equipment, packaging or instructions.  The warning comprises a symbol, as shown on the left, with a minimum height of 5 mm, and the following, or similar, wording: To prevent possible hearing damage, do not listen at high volume levels for long periods.

Scope of EN 50332

EN 50332 applies only to battery-operated portable consumer audio entertainment equipment with mono or stereo headphones or earphones, intended for presenting broadcast or recorded sound or video, for example CD players, MP3 players, MP3 players in mobile phones, or PDAs and tablets.  This standard does not cover mains-operated Hi-Fi or audio equipment, nor does it cover headphones used to aid the hard of hearing.  It also does not cover headphones or headsets used at work, e.g. headsets used with two-way radios or headsets in call centres, control rooms, or broadcasting.  Headphones used at work are covered separately by the requirements of the Control of Noise at Work Regulations 2005.  As well as testing to EN 50332, ISVR Consulting is able to measure sound levels and noise exposures from headsets and earpieces to assess compliance with the workplace regulations.

Legal status of EN 50332 and the sound limits

In France, the maximum sound level from headphones and earphones used with personal music players is limited by law to protect hearing.  It has been reported that all personal music players sold in the EU must restict headphone sound levels, as of February 2013, but at the moment this is not a legal requirement in member states apart from France. However, to avoid country-specific modifications or software and to sell the same model of music players or headphones throughout the EU, it is likely the players will need to comply with French law. Conforming to the recommended noise limits is also a sensible precaution to defend against personal injury claims for hearing impairment allegedly caused by personal music players and similar devices.

References

EN 50332-1:2013 Sound system equipment - Headphones and earphones associated with personal music players - Maximum sound pressure level measurement methodology  - Part 1  General method for “one package equipment”  (Identical to BS EN 50332-1:2013 in Britain, NF EN 50332-1:2013 in France or DIN EN 50332-1;2013 in Germany.) Back to text.

EN 50332-2:2013 Sound system equipment - Headphones and earphones associated with personal music players - Maximum sound pressure level measurement methodology - Part 2  Matching of sets with headphones if either or both are offered separately, or are offered as one package equipment but with stanardised connectors between the two allowing to combine components of different manufacturers or different design. (Identical to BS EN 50332-2;2013 in Britain, NF EN 50332-2;2013 in France or DIN EN 50332-2:2013 in Germany.) Back to text.

EN 60950-1:2006 with amendment A12:2011 Information technology equipment - Safety. part 1: general requirements.  (NB A later amended version was published in 2013, but EN 50332 specifies the 2011 version.) Back to text.

EN 60065:2002 with amendment A12:2011 Audio, video and similar electronic apparatus - safety requirements. Back to text