Telecommunications Industry Association
TR41.3.3-05-12-009
Document Cover Sheet
Project Number
SP-3-4352-RV2
Document Title
Maximum acoustic pressure comparison to UL60950 and IEEE 269
Source
Plantronics, Inc.
Contact
Name:
Complete
Address:
K. Allen Woo
Phone:
(831) 458-7351
345 Encinal St.
Fax:
(831) 458-0423
Email:
Allen.woo@plantronics.com
Santa Cruz, CA 95060
U.S.A.
Distribution
Intended Purpose
of Document
(Select one)
TR-41.3.3
X
For Incorporation Into TIA Publication
For Information
Other (describe) -
The document to which this cover statement is attached is submitted to a Formulating Group or
sub-element thereof of the Telecommunications Industry Association (TIA) in accordance with the
provisions of Sections 6.4.1–6.4.6 inclusive of the TIA Engineering Manual dated March 2005, all of
which provisions are hereby incorporated by reference.
Abstract
This contribution proposes new text for long duration maximum acoustic pressure measurements and
requirements for TIA 810B after comparing the measurements and requirement between TIA 810B, IEEE
Std 269 and UL/CSA 60950-2003.
v1.0 – 20050426
Telecommunications Industry Association
TR41.3.3-05-12-009
5.8 Long Duration Maximum Acoustic Pressure (Steady State Input)
5.8.1
General
The long duration maximum acoustic pressure is the steady state (longer than 500 ms) sound pressure
disturbance emitted from a telephone receiver, caused by the maximum excursions of the receive digital
signal.
Additional consideration should be given to the acoustic pressure caused by tones, other audio signals or
long duration, high amplitude electrical signals applied to power, network, handset or auxiliary leads of
the digital telephone.
5.8.2
Measurement Method
The steady-state A-weighted sound pressure level shall be measured using the digital terminals test
procedure in Clause 8.13 (Maximum Acoustic Output) of Error! Reference source not found., with the
following modifications.
Apply a digital square wave to the receive input, switched between the maximum positive and the
maximum negative values (see Error! Reference source not found.), as defined in ITU-T
Recommendation G.711. The switching rate shall range from 1 Hz to 8000 Hz (i.e., 0.5 Hz to 4000 Hz
square wave) over an elapsed time not less than 90 seconds for a logarithmic sweep. Logarithmic
frequency steps may be substituted for a sweep, provided that the step size is not greater than 1/12th
octave. The detector shall be set to rms fast, which is a 250ms effective averaging time (equivalent to a
125ms time constant). The detector shall be set to hold the maximum level achieved in each band during
the entire sweep.
Telephone sets with adjustable receive levels shall be adjusted to the maximum setting.
Maximum acoustic pressure limits can be referenced to the ERP, DRP, free field (0 degrees elevation and
azimuth) or to a diffuse field, as required by the appropriate safety standard. This may require that
measurements made at one reference point be translated to the required reference point.
Maximum acoustic pressure measurements shall be made on the same ear simulator and with the same
positioning and force as used for receive frequency response measurements. One additional measurement
shall be made at the low leak position. If both measurements fall below the applicable performance limit,
the measurement that most closely approaches the limit shall be taken as the final result. If one or both
measurements exceed the limit, the one that most exceeds the limit shall be taken as the final result.
A minimum of 5 measurements should be made. The final result should be the “upper envelop” curve
consisting of the maximum output of each measurement at each frequency. All curves should be reported.
See Clause 5.3 of IEEE Std 269.
5.8.3
Requirements
The measured maximum rms level should be less than 125 dB(A), required in UL/CSA 60950-2003.
Page 2 of 3
Telecommunications Industry Association
TR41.3.3-05-12-009
6.6 Long Duration Maximum Acoustic Pressure (Steady State Input)
6.6.1
General
The long duration maximum acoustic pressure is the steady state (longer than 500 ms) sound pressure
disturbance emitted from a telephone receiver, caused by the maximum excursions of the receive digital
signal.
Additional consideration should be given to the acoustic pressure caused by tones, other audio signals or
long duration, high amplitude electrical signals applied to power, network, headset or auxiliary leads of
the digital telephone.
6.6.2
Measurement Method
The steady-state A-weighted sound pressure level shall be measured using the digital terminals test
procedure in Error! Reference source not found..
Apply a digital square wave to the receive input, switched between the maximum positive and the
maximum negative values (see Error! Reference source not found.), as defined in ITU-T
Recommendation G.711. The switching rate shall range from 1 Hz to 8000 Hz (i.e., 0.5 Hz to 4000 Hz
square wave) over an elapsed time not less than 90 seconds for a logarithmic sweep. Logarithmic
frequency steps may be substituted for a sweep, provided that the step size is not greater than 1/12 th
octave. The detector shall be set to rms fast, which is a 250ms effective averaging time (equivalent to a
125ms time constant). The detector shall be set to hold the maximum level achieved in each band during
the entire sweep.
Headset telephone systems with adjustable receive levels shall be adjusted to the maximum setting.
Maximum acoustic pressure limits can be referenced to the ERP, DRP, free field (0 degrees elevation and
azimuth) or to a diffuse field, as required by the appropriate safety standard. This may require that
measurements made at one reference point be translated to the required reference point.
Maximum acoustic pressure measurements shall be made on the same ear simulator and with the same
coupling between the headset and the ear simulator as did for receive frequency response measurements.
A minimum of 5 measurements should be made. The final result should be the “upper envelop” curve
consisting of the maximum output of each measurement at each frequency. All curves should be reported.
See Clause 5.3 of IEEE Std 269.
6.6.3
Requirements
The measured maximum rms level shall be less than 118 dB(A), as required in UL/CSA 60950-2003
(editors note: UL/CSA 60950-2003 still calls 121 dB(A) for insert earphones which is incorrect).
Page 3 of 3