BS EN ISO 11904-2:2004 – Acoustics — Determination of sound immission from sound sources placed close to the ear — Part 2: Technique using a manikin

1 Scope
This part of ISO 1 1 904 specifies basic framework measurement methods for sound immission from sound sources placed close to the ear. These measurements are carried out with a manikin, equipped with ear simulators including microphones. The measured values are subsequently converted into corresponding freefield or diffuse-field levels. The results are given as free-field related or diffuse-field related equivalent continuous A-weighted sound pressure levels. The technique is denoted the manikin technique.
This part of ISO 1 1 904 is applicable to exposure to sound from sources close to the ear, for example during equipment tests or at the workplace to sound from earphones or hearing protectors with audiocommunication facilities.
This part of ISO 1 1 904 is applicable in the frequency range from 20 Hz to 1 0 kHz. For frequencies above 1 0 kHz, ISO 1 1 904-1 can be used.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
IEC 60942:2003, Electroacoustics — Sound calibrators
IEC 61 260:1 995, Electroacoustics — Octave-band and fractional-octave-band filters
IEC 61 672-1 , Electroacoustics — Sound level meters — Part 1: Specifications
ITU-T P.58:1 996, Head and torso simulator for telephonometry
GUM:1 993 , Guide to the expression of uncertainty in measurement. BIPM, IEC, IFCC, ISO, IUPAC, IUPAP,1 )
OIML, 1 995
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
manikin sound pressure level
L M,exp,f
equivalent continuous sound pressure level in one-third-octave frequency bands with nominal midband frequency f, measured with the microphone of an ear simulator integrated in a manikin when the manikin is exposed to the sound under test
3.2
free-field frequency response for use with manikins
∆L FF,M,f
average human free-field frequency response for use with manikins, corrected for the difference between the sound transmission inside the average human ear canal and the corresponding transmission of the manikin ear simulator
NOTE 1 For applicability with manikins, the eardrum reference is replaced by the output of the manikin ear simulator in tabulated values of ∆L FF,M,f .
NOTE 2 The free-field frequency response for use with manikins is identical to the amplitude of the head-related transfer function (HRTF) for frontal sound incidence.
NOTE 3 The human free-field frequency response is defined in ISO 1 1 904-1 .
BS EN ISO 11904-2:2004 – Acoustics — Determination of sound immission from sound sources placed close to the ear — Part 2: Technique using a manikin