We’ll Lend You Our Ears – When the Music Gets Loud

Let HATS take the blast and not your own ears. Increasingly, the European standard EN 50332 is being enforced. This standard is about the maximum sound pressure level permitted from portable audio players and requires the use of a Head and Torso Simulator (HATS) for the measurements.

The way we listen to music began changing with the introduction of the original Sony® Walkman® back in 1979 (cassette based). The change caught on when portable CD players became available, and with the introduction of MP3 players, portable devices with head- or earphones have become dominant. An increasing number of them include audio capabilities, and at times it's difficult to say whether the music player doubles as a cell phone or vice versa.

Not surprisingly, concern about possible damage to people's hearing, in particular children's hearing, is growing. Irrespective of the kind of portable device, EN 50332 sets a limit of 100 dB for the maximum sound pressure level allowed when using it for audio.

The standard requires the use of a HATS conforming to IEC 60959, and ear simulators conforming to IEC 60711 (in telecommunication terms this means that Type 3.3 ear simulators must be used). A specific test signal, programme simulation noise, defined in IEC 60268-1 is played at full volume and the maximum A-weighted sound pressure level is measured using an averaging time of 30s or more. The measurement is repeated five times - each time including a new mounting of the headphone - and the results averaged. The measured level is the level at the eardrum. In order to align this with epidemiological studies this level is converted into a free-field value. This correction can be applied during post-processing. However, if using a PULSE™ Data Acquisition and Analysis System, this is made automatically in real-time during measurement.