r at frequencies that would decrease the signal-
to-noise ratio specified in Item 4, then it is recommended that,
unless the noise can be reduced, an induction loop system not be
considered.

2.

If the electromagnetic signal produced by a nearby induction loop
system spills over into a new user area being considered for a
different induction loop system and produces an average magnetic
field strength exceeding 15 mA/meter, then it is recommended that,
unless the use of each system can be scheduled so as not to occur
simultaneously, an induction loop system not be considered in the new
area.

3.

Given an input signal to the amplifier that has a constant level over
a minimum frequency range of 100 Hz to 8,000 Hz, the measured frequency
response of the magnetic field generated by the induction loop system
over that range shall not vary by more than +/- 3 decibels from the
value at 1,000 Hz. In actual usage, graphic equalization of the output
signal is allowed.

4.

Given an output power level equal to the average value specified in
Item 6, the minimum signal-to-noise ratio of the program signal carried
by the electromagnetic field shall be at least 30 decibels.

5.

Given a 1,000 Hz input signal to the amplifier that has a level
sufficient to produce the minimum signal-to-noise ratio specified in
Item 4, the harmonic distortion between the input signal and the
program signal carried by the electromagnetic field shall not vary by
more than 5 percent over the field strength range specified in Item 6.

6.

Given a l,000 Hz sinusoidal input signal, at a level equal to the
long-time average level of a speech signal, the average value of the
magnetic field strength generated within the user area by the loop
shall equal 100 mA/meter +/- 3 decibels.

The maximum value of the magnetic field strength for a system set to the
above recommended average value shall be 400 mA/meter (derived on the basis
that the difference of the maximum short-time average level between a speech
signal approximately 0.125 seconds and the long-time average level is
approximately 12 decibels).

Both measurements shall be made 48 inches (1219 mm) above floor level at
any point within the user area.

7.

If a hand-held receiver with earphone(s) is used, the specifications
in Items 3, 4 and 5 shall apply. Additionally, the sound pressure
level generated by the receiver and earphone(s) shall be at least 80
decibels. The maximum high-frequency average sound pressure level generated
by the receiver earphone(s) shall not exceed 130 decibels.

8.

The system must have inputs capable of accepting signals at line
level and microphone level and must be capable of interfacing with
existing public address systems or stand-alone.

9.

Any stand-alone devices powered by 110-120 volt AC used as part of the
system must have been tested by an approved laboratory.

10.

All input and output wiring must comply with the New York City Electrical Code.

11.

The installation of all stand-alone components of the system must
comply with the New York City Electrical Code.

SECTION BC N103
INFRA-RED SYSTEM

N103.1 Infra-red system specifications.

1.

If the ambient infra-red light (generally caused by other infra-red
light-generating devices or direct sunlight) produces interference, it
is recommended that, unless the interfering infra-red light can be
reduced, infra-red systems not be considered.

2.

Given an input signal to the transmitter at the levels
specified in Item 6 over a minimum frequency range of 200 Hz to 8,000
Hz, the measured frequency response of the output signal generated by
the receiver and transducer over that range shall not vary by more
than +/- 5 decibels from the value at 1,000 Hz. In actual usage, graphic
equalization of the output signal is allowed.

3.

Given an input signal to the transmitter at the levels
specified in Item 6, the minimum signal-to-noise ratio of the output
generated by the receiver and transducer shall be 35 decibels at all
frequencies specified in Item 2.

4.

Given an input signal of 1,000 Hz to the transmitter at a level
sufficient to produce the minimum signal-to-noise ratio specified in
Item 3, the harmonic distortion produced by the receiver and
transducer shall not be more than 5 percent.

5.

Given a 1,000 Hz sinusoidal input signal at the levels

specified in Item 6, the following are the possible transducers:

5.1. If using a neckloop as an output transducer, generate a
magnetic field strength of at least 150 mA/meter. The peak field
strength shall not exceed 600 mA/meter. Measurements shall be
made at the geometric center of the plane of the neckloop.

5.2. If using a silhouette as an output transducer, generate a magnetic
field strength of at least 50 mA/meter (the peak field strength
shall not exceed 200 mA/meter). Measurements shall be made at a
distance of 10 centimeters from the silhouette.

5.3. If using a miniature earphone as an output transducer, generate a
sound pressure level of at least 80 decibels. The maximum high-
frequency average sound pressure level shall not exceed 130
decibels.

5.4. If a direct input cable is used between the output of the receiver
and the input of a hearing aid boot or shoe, generate a minimum
voltage range of 2 mV to 800 mV and match a boot/shoe input
impedance of 50 ohms or greater. The plugs at either end shall be
molded 2-pin, 3-pin and/or 3.5-millimeter mini-plug (stereo or
mono).

6.

The system must have inputs capable of accepting signals at line
level and microphone level and must be capable of interfacing with
existing public address systems or stand-alone.

7.

The minimum light level of the transmitted infra-red carrier signal
must be sufficient so that a receiver can produce the specifications in
Items 2, 3, 4 and 5 at any point within the user area.

8.

Any stand-alone devices powered by 110-120 volt AC used as part of
the system must be tested by an approved laboratory.

9. All input wiring must comply with the New York City Electrical Code.

10.
The installation of all stand-alone components of the system must
comply with the New York City Electrical Code.

SECTION BC N104
FM SYSTEM

N104.1 FM system specifications.

1.

If an ambient FM signal (generally caused by other agencies on the
same frequency or major power supplies) produces interference, it is
recommended that, unless the frequency can be changed, an FM system not
be considered.

2.

Given an input signal to the transmitter at the levels
specified in Item 6 over a minimum frequency range of 100 Hz to 8,000
Hz, the measured frequency response of the output signal generated by
the receiver and a transducer over that range shall not vary by more
than +/- 5 decibels from the value at 1,000 Hz. In actual usage,
graphic equalization of the output signal is allowed.

3.

Given an input signal to the transmitter at the levels
specified in Item 6, the minimum signal-to-noise ratio of the output
generated by the receiver and transducer shall be 35 decibels at all
frequencies specified in Item 2.

4.

Given an input signal to the transmitter at 1,000 Hz. at a level
sufficient to produce the minimum signal-to-noise ratio specified in
Item 3, the total harmonic distortion between the input signal and the
program signal produced by the receiver and transducer shall not be
more than 10 percent.

5.

Given a 1,000 Hz. sinusoidal input signal at the levels

specified in Item 6, the following are among the possible transducers:

5.1. If using a neckloop as an output transducer, generate a magnetic
field strength of at least 150 mA/meter. The peak field strength
shall not exceed 600 mA/meter. Measurements shall be made at the
geometric center of the plane of the neckloop.

5.2. If using a silhouette as an output transducer, generate a magnetic
field strength of at least 50 mA/meter. The peak field strength
shall not exceed 200 mA/meter. Measurements shall be made at a
distance of 10 centimeters from the silhouette.

5.3. If using a miniature earphone as an output transducer, generate a
sound pressure level of at least 80 decibels. The maximum high-
frequency average sound pressure level shall not exceed 130
decibels.

5.4. If a direct input cable is used between the output of the receiver
and the input of a hearing aid boot or shoe, generate a minimum
voltage range of 2 mV to 800 mV and match a boot/shoe input
impedance of 50 ohms or greater. The plugs at either end shall be
molded 2-pin, 3-pin and/or 3.5-millimeter mini-plug (stereo or
mono).

6.

The system must have inputs capable of accepting signals at line
level and microphone level and must be capable of interfacing with
existing public address systems or stand-alone.

7.

The minimum sensitivity of the receiver shall be at least 2 �V at 12
decibel SINAD. The maximum RF signal generated by the transmitter
shall not exceed 8,000 �V/meter at 30 meters.

8.

Any stand-alone devices powered by 110-120 volt AC used as part of
the system must be tested by an approved laboratory.

9.

All input and output wiring must comply with the New York City Electrical Code.

10.

The installation of all stand-alone components of the system must
comply with the Ne