BS EN 60268-7:2011 pdf download

BS EN 60268-7:2011 pdf download.Sound system equipment -Part 7: Headphones and earphones.
7.2 Standard conditions for measurement
A headphone is working under standard conditions for measurement when all of the following conditions are fulfilled
a) At east one earphone is applied to the appropriate coupler or ear simulator, with the rated application force.
b) A sinusoidal voltage at the standard measuring frequency Is applied. In series with the rated source impedance. The voltage shall be such that a sound pressure level of 94 dB (reference 20 pPa) Is generated in the coupler or ear simulator. Unless otherwise stated, the standard measuring frequency shall be 500 Hz. The input signal shall be applied at the point where the signal from an amplifier or other equipment Is applied when the headphone Is in use. This point may be the input of a piece of auxiliary equipment, such as a preamplifier.
As an alternative, the manufacturer may specify this condition as being a signal voltage which dissipates a power of 1 mW in a pure resistance equal to the rated impedance of the earphone being measured.
NOTE EI.cirostat.c, pi.zo-.I.ctric, .l.ctret condenser and cordless headphones ar, within the scope of this standard. The signal may be sent to the headphone by infra-red. radio, light or magnetic induction feather directly to the transducers or to a magnetic pick-up device and amplifier). These types of headphone are more easily dealt with by specifywig th sound pressure level to be generated (the input signal being applied to the transmitter unit). rather than by specifying the power in the rated impedance.
C) Unless otherwise specified by the manufacturer, volume controls are set at minimum attenuation. For headphones supplied with a preamplifier, and for cordless headphones, the manufacturer shall specify a reference position of the gain control for use in measurements. Other controls shall be set at the designated normals positions, or at stated positions. preferably those giving the greatest range of frequency response. Balance controls shall be set for equal voltages at the terminals of the Channels. Crosstalk controls shall be set for minimum crosstalk.
d) If the headphone requires a power supply, the rated supply voltage and frequency are applied.
7.3 Couplers and ear simulators
The manufacturer should use the coupler or ear simulator which is specified in the international standard for the measurement of the headphone or earphone, for which results are to be published. The manufacturer shall state the type of the used coupler or ear simulator In the results.
NOTE Examples the internstional standards specifying th, couplers and ear simulators are IEC 80318.1.
PEC 60318-2, IEC 60318-3, iEc 60318-5, iEc 60711, ITU.T Recommendation P.57, 4.3 and the ear part of HATS
(Head and torso simulator) In IEC 60959
For the measurement using the ear part of HATS (Head and Torso Simulator). the manufacturer should use the model specified in IEC 60959 or equivalent. see ITU Recommendation P.58 Hardness of the rubber pinna used shall be stated in the results, see ISO 7619-1 (2004).
Information for the pinna simulator suitable for measurements of headphones is given in Annex A.
If the coupler or ear simulator except specified in the international standards was used, the manufacturer shall state its physical parameters, shape, dimension, volume of the cavity. etc., to maintain repeatability of measurement,
7.4 Measurement conditions for simulated programme signal
The conaition spocif ted in 7.2 are applied except that the simulated progrrnme signal specified In IEC 60268-1 shall be applied. The following fillers can be used to process the output signal of the ear simulator:
75.2 Free-field comparison conditions
A headphone is working under free-field comparison conditions when both of the following conditions are fulfilled:
a) the headphone is worn by a test person in accordance with the manufacturers instructions or in the usual way for that type. It is necessary to fit the headphone in accordance with the manufacturers instructions. so that the earphones are correctly positioned. and the application force is close to the rated value:
b) the reference sound field simulates a progressive plane wave The acoustic signal shall have a specified bandwidth and Sound pressure level at a stated reference point, in the absence of the test person.