COMMENTS ON SECTION 6 from ALLEN WOO, PLANTRONICS
TR41.3.3-01-08-019
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Magnuson)
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COMMENTS ON SECTION 6 from ALLEN WOO, PLANTRONICS
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COMMENTS ON SECTION 6 from ALLEN WOO, PLANTRONICS
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6. Headset Technical Requirements
If the telephone also supports narrowband mode, then the telephone must also meet the requirements
in Section 6 of ANSI/TIA/EIA-810A-2000.
All telephones shall (@@@ Put CODEC HERE) If the telephone uses other vocoders, the
manufacturer must ensure that their implementation passes the standard test vectors associated with
that codec. For bit exact vocoders, such as G.729, it is important to ensure that vector testing has
been performed and found to be compliant with the associated ITU requirement.
Unless specified otherwise:
Encoding and decoding is assuming to be (@@@ Put CODEC HERE)
|
Algorithmic processes, such as Echo Control, VAD and AGC, may influence the test results or
require test signals other than sinewaves. ITU-T Recommendation P.64 allows several types of test
signals. The test signal used should be stated. The test signal levels specified in this standard shall be
used. Test signal levels that differ from those specified in this standard may also be required.
Packet voice latency may introduce significant delay that must be accounted for by the test
equipment.
Equipment using nonlinear voice signal processing may require subjective testing.
Suitable ear simulator for tests involving the headset receiver are documented in IEEE 269 (200x).
The correct ear simulator is selected by the size, ear coupling method, impedance and bandwidth
characteristics of the device under test. All tests involving the headset receiver shall be done with the
same ear simulator. All test reports shall document the model of ear simulator used in the tests.
The headset test method is given in IEEE 269 (200x).
6.1. Headset Frequency Response
6.1.1. Headset Send Frequency Response
The send frequency response is the overall response of the transducer, send amplifier, and the codec
send filter. The send sensitivity is the ratio of the send frequency response to the sound pressure at
MRP for each frequency or frequency band (Fi) as shown in Equation 1. It is expressed in terms of
dBV/Pa.
6.1.1.1.
Measurement Method
The send frequency response is measured according to IEEE 269 (200x) using the measurement setup shown in Error! Reference source not found., substituting the handset with a headset [@@@
re-draw Figure 3 with test on HATS].,. The test signal level shall be -4.7 dBPa at the MRP over a
minimum range of 100 Hz through 8000 Hz with ISO 1/12 octave intervals or smaller. Measurements
should be done at RTP (Recommend Test Position from manufacturer). If RTP is not available BMP
(Boom Microphone Position) or STP (Standard Test Position) shall be used.
6.1.1.2.
Requirement
The send frequency response shall fall between the upper and lower limit defined in Table 1 and
shown in Figure 1. The limit curves shall be determined by straight lines joining successive coordinates given in the table, when frequency response is plotted on a linear dB scale against
frequency on a logarithmic scale. Note: The frequency response mask is a floating or “best fit” mask.
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TR41.3.3-01-08-019
COMMENTS ON SECTION 6 from ALLEN WOO, PLANTRONICS
Table 1 – Co-ordinates of Headset Send Response Limits
Limit Curve
upper limit
lower limit
Frequency
(Hz)
Send Response Limit
(dB) [arbitrary level]
100
0
8000
8000
0
-infinity
200
200
250
5000
6300
6300
- infinity
-11
-8
-8
-11
-infinity
10
Ar 0
bit
rar
y
Le
vel
(d -10
B)
-20
100
1000
10000
Frequency (Hz)
Figure 1 – Headset Send Frequency Response Mask
6.1.2. Headset Receive Frequency Response
The receive frequency response is the overall response of the codec receive filter, receive amplifier
and transducer. The receive sensitivity is ratio of the receive frequency response to the voltage input
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TR41.3.3-01-08-019
to the reference codec, or digital bit stream equivalent for each frequency or frequency band (Fi) as
shown in the Equation 2. It is expressed in terms of dBPa/V.
6.1.2.1.
Measurement Method
The receive frequency response is measured according to IEEE 269 (200x) using the measurement
set-up shown in Error! Reference source not found., substituting the handset with a headset
[@@@ re-draw Figure 5 with testing on HATS]. Measurements should be done in ISO 1/12 octave
intervals or smaller, over a minimum range of 100 Hz through 8000 Hz. The test signal level shall be
-18.2 dBV (-16 dBm0). Telephone sets with adjustable receive levels shall be adjusted so that their
RLR is as close as possible to the nominal value of Section 5.2.2.2 for this test.
6.1.2.2.
Requirement
The receive frequency response shall fall between the upper limit and the lower limit defined in
Table 2 and shown in Figure 2. The limit curves shall be determined by straight lines joining
successive co-ordinates given in the table, when frequency response is plotted on a linear dB scale
against frequency on a logarithmic scale. Note: The frequency response mask is a floating or “best
fit” mask.
6.2. Headset Loudness Ratings
6.2.1. Headset Send Loudness Rating (SLRw)
The SLRw for a digital telephone set is the conversion ratio of a defined acoustic signal at MRP to
the send signal at the interface. Refer to Annex A and ITU-T Recommendation P.79. [@@@ see
comment in section 5.2.1]
6.2.1.1.
Measurement Method
The SLRw shall be calculated using the 1/3 octave sensitivity data collected from the send frequency
response measurement. [@@@ see comment in section 5.2.1.1] Use equation [A1] of Annex A and
bands 1 to 20, Error! Reference source not found..
6.2.1.2.
Requirement
The terminal should be designed to have a nominal SLRw value of [@@@ to be decided] dB, with a
tolerance of ±5.0 dB.
6.2.2. Headset Receive Loudness Rating (RLRw)
The RLRw for a digital telephone set is the conversion ratio of a defined electrical signal at the
digital reference point to an acoustic output signal from the receiver. Refer to Annex A and ITU-T
Recommendation P.79.
6.2.2.1.
Measurement Method
The headset is mounted as specified by IEEE 269 (200x) and the receiver is coupled to the
appropriate ear simulator. The RLRw shall be calculated from the 1/3 octave sensitivity data
collected from the receive frequency response measurement. Use equation [A2] of Annex A and
bands 1 to 20, Error! Reference source not found..
6.2.2.2.
Requirement
The monaural terminal should have a nominal RLRw value of 0 dB, with a tolerance of ±4.0 dB. The
binaural terminal should have a nominal RLRw value of 6 dB, with a tolerance of ±4.0 dB, for each
of the receivers measured separately.
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COMMENTS ON SECTION 6 from ALLEN WOO, PLANTRONICS
TR41.3.3-01-08-019
Note 1: Headset RLRws are louder than handset RLRs to compensate for lack of noise
occlusion???.
Note 2: Either the terminal or the headset should have a receive volume control that is capable of
amplification and attenuation.
Table 2 – Co-ordinates of Headset Receive Response Limits
Limit Curve
upper limit
lower limit
Frequency
(Hz)
Receive Response Limit
(dB) [arbitrary level]
100
150
1000
3000
5000
8000
200
200
250
5000
6300
6300
-7
0
0
5
5
0
- infinity
-11
-8
-8
-11
-infinity
Figure 2 – Headset Receive Frequency Response Mask
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Arbitrary Level (dB)
5
0
-5
-10
-15
-20
100
1000
Frequency (Hz)
(@@@ New Mask corresponds Table 6 to be inserted here)
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TR41.3.3-01-08-019
6.2.3. Headset Talker Sidetone
The sidetone masking rating (STMR) for a digital telephone set is the ratio of a defined input
acoustic signal at MRP to the resulting acoustic output signal from the receiver. It’s desirable for the
STMR to be constant over the receive volume control range.
6.2.3.1.
Measurement Method
The headset is mounted as specified by IEEE 269 (200x) and the receiver is coupled to the
appropriate ear simulator. The test signal level at the MRP shall be -4.7 dBPa. For each frequency
given in Error! Reference source not found., bands 1 to 20, the sound pressure in the ear simulator
shall be measured. The STMR shall be calculated using equation [A3] of Annex A.
Telephone sets with adjustable receive levels shall be tested at the minimum, nominal and maximum
settings. For the nominal setting, adjust the level so that the RLRw is as close as possible to the
nominal RLRw value.
6.2.3.2.
Requirement
For any adjustable receive level, the value of STMR shall be within the range of 21 dB ± 6 dB for
supra-aural and supra-concha [@@@ for what reason supra-concha have to be 3 dB better than interconcha?], 18 dB ± 6 dB for insert, 18 dB ± 6 dB for inter-concha. The value of STMR for binaural
terminals should be 6 dB quieter, for each of the receivers measured separately.
6.3. Headset Noise
The noise levels are related to the SLRw and RLRw requirements. [@@@ what does this mean?]
6.3.1. Headset Send Noise
The following requirements apply to headset and 64 kbit/s, PCM digital telephones only.
6.3.1.1.
General
The send noise of a digital telephone is the 5 second average noise at the digital transmit output with
the headset transmitter isolated from sound input and mechanical disturbances.
6.3.1.2.
Measurement Method
With the headset mounted as specified by IEEE 269 (200x) and the receiver coupled to the
appropriate ear simulator in a quiet environment (ambient noise less than 30 dBA), free of
mechanical disturbances, measure the noise level at the digital interface output or the reference codec
decoder output with apparatus that includes, AWeighted.
6.3.1.3.
Requirement
The send noise shall be no greater than -64 dBm0p, A-Weighted.
6.3.2. Headset Send Single Frequency Interference
6.3.2.1.
General
Narrow-Band noise, including single frequency interference, is an impairment that can be perceived
as a tone depending on its level relative to the overall weighted noise level. This test measures the
weighted noise level characteristics in narrow bands of not more than 31 Hz, which can then be
compared to the overall weighted background noise level.
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COMMENTS ON SECTION 6 from ALLEN WOO, PLANTRONICS
6.3.2.2.
TR41.3.3-01-08-019
Measurement Method
With the headset mounted as specified by IEEE 269 (200x) and the receiver coupled to the
appropriate ear simulator in a quiet environment (ambient noise less than 30 dBA), free of
mechanical disturbances, measure the A-weighted noise level at VSEND with a selective voltmeter or
spectrum analyzer with an effective bandwidth of not more than 31 Hz, over the frequency range of
100 to 8000 Hz. If FFT analysis is used, then “Flat Top” windowing shall be employed.
6.3.2.3.
Requirement
The send single frequency interference shall be no greater than nn A-weighted (@@@ TBD)
6.3.3. Headset Receive Noise
6.3.3.1.
General
The receive noise of a digital telephone is the short-term average background noise level measured at
the output of the headset receiver with the digital telephone receiving the digital quiet code.
6.3.3.2.
Measurement Method
The headset is mounted as specified by IEEE 269 (200x). A signal corresponding to a decoder quiet
code is applied at the digital interface. The A-weighted noise level is measured in the ear simulator.
The ambient noise for this measurement shall not exceed 30 dBA.
Telephone sets with adjustable receive levels shall be adjusted so that the RLR is as close as possible
to the nominal RLR value when driven by quiet code.
6.3.3.3.
Requirement
The receive noise shall be less than 40 dBA for a monaural headset. The receive noise for binaural
headsets should be less than 34 dBA, for each of the receivers measured separately.
6.3.4. Headset Receive Single Frequency Interference
6.3.4.1.
General
Narrow-Band noise, including single frequency interference, is an impairment that can be perceived
as a tone depending on its level relative to the overall weighted noise level. This test measures the
weighted noise level characteristics in narrow bands of not more than 31 Hz, which can then be
compared to the overall weighted background noise level. Narrow-band noise is measured at the
output of the telephone receiver with the digital telephone receiving the digital quiet code.
6.3.4.2.
Measurement Method
The headset is mounted as specified by IEEE 269 (200x) and the receiver is coupled to the
appropriate ear simulator. A signal corresponding to a decoder quiet code is applied at the digital
interface. The A-weighted noise level is measured in the ear simulator with a selective voltmeter or
spectrum analyzer, with an effective bandwidth of not more then 31 Hz, over the frequency range of
100 to 8000 Hz. If FFT analysis is used, then “Flat Top” windowing shall be employed. The ambient
noise for this measurement shall not exceed 30 dBA.
Telephone sets with adjustable receive levels shall be adjusted so that the RLR is as close as possible
to the nominal RLR value when driven by quiet code.
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6.3.4.3.
Requirement
The receive single frequency interference shall be 10 dB quieter than the A-weighted broadband
noise floor.
6.4. Headset Distortion and Noise
The distortion and noise requirements only apply to G.xxx codecs in mu-law.
6.4.1. Headset Send Distortion and Noise
6.4.1.1.
Method of Measurement
The distortion and noise is measured according to IEEE 1329, 9.3.6. Apply a sinewave signal at the
MRP, with the levels given in Error! Reference source not found. and the following frequencies:
315, 502, 803 and 1004 Hz. The ratio of the signal-to-total distortion and noise power of the digitally
encoded signal output is measured. The test frequency tolerance is 3%, but even submultiples of the
sampling frequency must not be used.
Note: In cases where the sound pressure exceeds +6 dBPa, the linearity of the artificial mouth should
be checked, as it exceeds the limits of ITU-T Recommendation P.51.
Table 3 – Headset Send Signal-to-Total Distortion and Noise Ratio Limits
Send level at the MRP
(dBPa)
Send Ratio
(dB)
-30
-24
-17
-10
0
+4
+8
+10
20
25
31
33
33
33
24
20
(@@@ Table needs updating)
6.4.1.2.
Requirement
The ratio of signal-to-total distortion and noise power of the digitally encoded signal output shall be
above the limits given in Table 3. Limits for intermediate levels are found by drawing straight lines
between the breaking points in the table on a linear (dB signal level) – linear (dB ratio) scale.
6.4.2. Headset Receive Distortion and Noise
6.4.2.1.
Method of Measurement
The headset is mounted as specified by IEEE 269 (200x) and the receiver is coupled to the
appropriate ear simulator. The distortion and noise is measured according to IEEE 1329, 9.4.6. Apply
a digitally simulated sinewave, with the levels given in Error! Reference source not found. and the
following frequencies: 315, 502, 803 and 1004 Hz. The ratio of signal-to-total distortion and noise
power is measured in the ear simulator. The test frequency tolerance is 3%, but even submultiples of
the sampling frequency must not be used.
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COMMENTS ON SECTION 6 from ALLEN WOO, PLANTRONICS
TR41.3.3-01-08-019
Telephone sets with adjustable receive levels shall be adjusted so that the RLR is as close as possible
to the nominal RLR value.
6.4.2.2.
Requirement
The ratio of signal-to-total distortion and noise power measured in the ear simulator, with Aweighting applied, shall be above the limits given in Table 4, unless the signal in the ear simulator
exceeds +10 dBPa or is less than –50 dBPa.
Table 4 – Headset Receive Signal-to-Total Distortion and Noise Ratio Limits
Receive level at the digital
interface
(dBm0)
-40
-34
-27
-20
-10
-6
-3
0
(@@@ Table needs updating)
Receive Ratio
@ 315 Hz
(dB)
Receive Ratio
@ 502, 803 and 1004 Hz
(dB)
19
24
30
32
32
32
28
23
20
25
31
33
33
33
29
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6.5. Weighted Terminal Coupling Loss (TCLw)
The weighted terminal coupling loss (TCLw) provides a measure of the echo performance under
normal conversation.
6.5.1. Measurement Method
TCLw is measured in free-air in such a way that the inherent mechanical coupling of the headset is
not affected. The TCLw measurement shall be made at an input signal level of
-16 dBm0. The test shall be performed with the headset suspended in a noose around the earcap with
the headset cord hanging freely below the headset.
For devices that incorporate non-linear processes, additional measurements using signal levels of
-26 dBm0 and -10 dBm0 may be performed.
Noise and reflections in the test space must not influence the measurement. The test should be
performed in an anechoic chamber with the headset positioned at least 50 cm away from the nearest
part of the test chamber. The ambient noise level shall be less than 30 dB(A).
The test signal is (@@@ Need to define test signal) white noise, band limited to 100 through 8000
Hz, and modulated at a rate of 250 ms ON and 150 ms OFF. The measurement and calibration shall
be determined during the ON portions of the signal. Sine wave signals may be used with G.xxx
codecs.
The attenuation from digital input to digital output is measured at 1/12 octave frequencies as given
by the R.40-series of preferred numbers in ISO 3 for frequencies from 290 to 8000 Hz, using the
measurement arrangement shown in Figure 3. See Annex C.
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TR41.3.3-01-08-019
The weighted terminal coupling loss is calculated according to ITU-T Recommendation G.122
(1993) Annex B, Section B.4 (trapezoidal rule).
Telephone sets with adjustable receive levels shall be tested at the nominal setting. For the nominal
setting, adjust the level so that the RLR is as close as possible to the nominal RLR value.
6.5.2. Requirements
The normalized value of TCLw loss shall be greater than 52 dB for IP sets and 45 dB for PCM sets
when measured under free field conditions and with SLR normalized to 8 dB and RLR normalized to
0 dB. It is desirable that the normalized value of TCLw for IP sets to be greater than 55 dB and that
the normalized value of TCLw for PCM sets be greater than 50 dB.
For example, if the measured TCLw is 48 dB, the measured SLR is 10 dB and the measured RLR is
2 dB, then the normalized value of TCLw = 48 dB + (8 - 10) dB + (0 - 2) dB = 44 dB.
NOTE 1: If equipped with adjustable receive level, the TCLw will decrease in proportion with the
increased gain relative to the nominal RLR in most cases. For example, if the measured
TCLw is 45 dB at nominal RLR and the adjustable receive level adds 12 dB of gain, then
TCLw (maximum receive level) = 45 dB - 12 dB = 33 dB.
NOTE 2: The echo impairment perceived by the person at the opposite end of the connection from a
telephone set is a function of the magnitude of the talker echo signal as well as the talker
echo path delay. The echo signal becomes more disturbing as the talker echo path delay
increases. Thus, a telephone set with adequate TCLw performance on low delay
connections may provide satisfactory performance while the same may not be true for
connections that have a long delay.
NOTE 3: Temporally weighted terminal coupling loss (TCLt) is an alternate method for echo
measurement, which may be more subjectively relevant, especially in devices with echo
suppression or cancellation features. (See IEEE Standard 1329-1999.) The performance
requirements may need to be changed when using this method. This issue is currently
under study.
Figure 3 – Terminal Coupling Loss Measurement Method
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