IEC 60118-6:1999 pdf download – Hearing aids -Part 6: Characteristics of electrical input circuits for hearing aids

IEC 60118-6:1999 pdf download – Hearing aids -Part 6: Characteristics of electrical input circuits for hearing aids.
This part of IEC 60118 specifies the electrical and safety characteristics of a circuit for an external electrical input to a personal hearing aid in order to ensure compatibility with external electrical or electroacoustic signal sources. In this standard, the hearing aid may include an adaptor (audio shoe) which incorporates connector systems described in IEC 60118-12.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of lEG 60118. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of lEG 60118 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of IEC and ISO maintain registers of currently valid International Standards.
IEC 60065, Audio video and similar electronic apparatus – Safety requirements
lEG 60118-0, Hearing aids — Part 0: Measurement at electroacoustical characteristics Amendment I
IEC 601 18-12, Hearing aids — Part 12: Dimensions of electrical connector systems
3 Electrical characteristics
3.1 Input impedance
The modulus of the impedance at the signal input terminal shall be at least 2 000 fi in the frequency range 200 Hz to 10 kHz and shall be specified by the manufacturer.
3.2 Input sensitivity
The input sensitivity level at the signal input terminal is that voltage level relative to 1 V in decibels, which gives an output from the hearing aid equal to that generated by an input sound pressure level to the microphone relative to 20 l4Pa of 70 dB at the same gain setting at the reference test frequency of 1 600 Hz, or 2 500 Hz according to IEC 6011 8•0 as appropriate. The input sensitivity level relative to I V shall be —54 dB and the tolerances on this value shall be staled by the manufacturer.
The signal Input terminal shall be designed to withstand a d.c. voltage of at least 1.5 V and an ac. voltage of at least 1.0 V (r.ms, value),
4 Mechanical characteristics and electrical function of connector system for electrical input
It is recommended to use one of the threeterminal connector systems (the three-terminal polarized plug or the three-terminal circular connector system) described in IEC 60118-12. The piflS of the three-terminal polarized plug shall have the following electrical functions: thick pin:
common; mid pin: supply voltage (ii used) and third pin: signal. The pins of the three-lerminal circular connector system shall have the following electrical functions: pin 1: common; pin 2:
supply voltage (ii any) and pin 3: signal.
5 ElectrIcal safety
A hearing aid shall not be connected to mains-operated equipment If the equipment does not meet the safety requirements laid down in IEC 60065 andor in appropriate national standards.