G.R.A.S. Sound &Vibration A/S
Artificial Ear Dilemma
Historical
IEC 60318
IEC 60711
Anatomical variations
Combined coupler and pinna
Closed-coupler testing
Free-field testing
Zwislocki to IEC correction
G.R.A.S. Sound &Vibration A/S
Historical
French Artificial Ear made by CNET
G.R.A.S. Sound &Vibration A/S
Historical
Swiss Artificial Ear made by the Swiss P.T.T.
G.R.A.S. Sound &Vibration A/S
NBS 9-A Earphone Coupler
Historical
G.R.A.S. Sound &Vibration A/S
The IEC 60318-1 ear. The impedance and lumped parameter electrical network is shown in the IEC 60318-1 standard.
IEC 60318
G.R.A.S. Sound &Vibration A/S
IEC 60318
Frequency response obtained by a ½”condenser microphone receiver and transmitter mounted concentrically at the top and bottom of the variously shaped coupler volumes. Valid for the range 500-20000 Hz. All coupler dimensions are given in millimeters. Vertical scale 2dB per line, 50dB full scale.
G.R.A.S. Sound &Vibration A/S
IEC 60318
Detailed measurements to determine the optimum dimensions for the best possible linearity over the widest frequency range. 10dB full scale. 0.4 dB per line.
G.R.A.S. Sound &Vibration A/S
IEC 60711
G.R.A.S. RA0045 occluded ear simulator as used in KEMAR
G.R.A.S. Sound &Vibration A/S
Ear moulds from same person. Right and left ears. The width at the most narrow passage is 6mm for the left ear and 9.6mm for the right ear.
Anatomical variations
G.R.A.S. Sound &Vibration A/S
Combined coupler and pinna
Type 43AG Ear and Cheek Simulator with IEC 60711 Coupler
G.R.A.S. Sound &Vibration A/S
Closed-coupler testing
Telephone Test Head Type 45AA showing:
Left; fitted with a G.R.A.S. Mouth Simulator & IEC 60318 Ear Simulator Type 43AD.
Right; computer rendering outlining its chief components
G.R.A.S. Sound &Vibration A/S
Speaking positions according to current recommendations
Closed-coupler testing
Speaking Position Recommendation
LRGP ITU-T Rec. P76
AEN ITU-T Rec. P76
HATS ITU-T P58
REF OREM A
G.R.A.S. Sound &Vibration A/S
Closed-coupler testing
Showing where the Lip-ring of the Mouth Simulator (Type 44AA or 44AB) should be for both AEN and REF positions. The angular distances of 39° and 13° (in that order) will move the handset from the AEN position to the LRGP
G.R.A.S. Sound &Vibration A/S
Free-field testing
KEMAR with positioning device
G.R.A.S. Sound &Vibration A/S
Free-field testing
KEMAR with reference microphone for linearization
G.R.A.S. Sound &Vibration A/S
Free-field testing
Auricle Measures used in KEMAR
G.R.A.S. Sound &Vibration A/S
Free-field testing
Mean values of frequencies of pressure maxima and minima at the open ear canal entrance for 12 male and female subjects; sound incidence from 90; loudspeaker source at 1m.
Equivalent lengths based on c=354 m/sfor l1 and l3, c=349.5 for L1 and L3.
G.R.A.S. Sound &Vibration A/S
Free-field testing
Ear canal entrance sound pressure, 12 females (above), 12 males (below), sound source at 90º azimuth angle, 1m.Free field is the reference pressure condition
G.R.A.S. Sound &Vibration A/S
Free-field testing
KEMAR Ear drum sound pressure for a free sound field with source azimuth angles of 0°, 90°, 180°, and 270°.
G.R.A.S. Sound &Vibration A/S
Zwislocki to IEC correction
15 IEC Modulus values of the acoustic transfer impedance function from IEC 711-1982 relative to the ANSI modulus values of the acoustic transfer impedance function.
