7.2 Overall loss/loudness ratings

26.1313GPPRelease 17RequirementsTerminal acoustic characteristics for telephonyTS

7.2.1 General

An international connection involving a 3G, LTE, NR or WLAN network and the PSTN should meet the overall loudness rating (OLR) limits in ITU-T Recommendation G.111 [4]. The national parts of the connection should therefore meet the send and receive loudness rating (SLR, RLR) limits in ITU-T Recommendation G.121 [5].

For the case where digital routings are used to connect the 3G, LTE, NR or WLAN network to the international chain of circuits, the SLR and RLR of the national extension will be largely determined by the SLR and RLR of the 3G, LTE, NR or WLAN network. The limits given below are consistent with the national extension limits and long term objectives in ITU-T Recommendation G.121 [5].

The SLR and RLR values for the 3G, LTE, NR or WLAN network apply up to the POI. However, the main determining factors are the characteristics of the UE, including the analogue to digital conversion (ADC) and digital to analogue conversion (DAC). In practice, it is convenient to specify loudness ratings to the Air Interface. For the normal case, where the 3G, LTE, NR or WLAN network introduces no additional loss between the Air Interface and the POI, the loudness ratings to the PSTN boundary (POI) will be the same as the loudness ratings measured at the Air Interface. However, in some cases loss adjustment may be needed for interworking situations in individual countries.

7.2.2 Connections with handset UE

The nominal values of SLR/RLR to the POI shall be:

SLR = 8 ± 3 dB;

RLR = 2 ± 3 dB.

Where a user-controlled receiving volume control is provided, the RLR shall meet the nominal value for at least one setting of the control. When the control is set to maximum, the RLR shall not be ≤ (equal or louder than) -13 dB and shall not be ≥ (equal or quieter than) ‑3 dB.

With the volume control set to the minimum position the RLR shall not be ≥ (equal or quieter than) 18 dB.

Compliance shall be checked by the relevant tests described in TS 26.132.

7.2.2a Connections with handset UE in the presence of background noise

In the presence of background noise, the RLR at maximum volume control shall not be ≤ (equal or louder than) ‑13 dB.

Compliance shall be checked by the relevant tests described in TS 26.132.

7.2.3 Connections with desktop and vehicle-mounted hands-free UE

The nominal values of SLR/RLR to/from the POI shall be:

SLR = 13 ± 4 dB;

RLR = 2 ± 4 dB (for vehicle-mounted hands-free UE);

RLR = 5 ± 4 dB (for desktop hands-free UE).

1. For a vehicle-mounted hands-free UE:
Where a user-controlled volume control is provided, the RLR shall meet the nominal value for at least one setting of the control. It is recommended that a volume control giving at least 15 dB increase from the nominal RLR (louder) is provided for hands-free units intended to work in the vehicle environment. This is to allow for the increased acoustic noise level in a moving vehicle.
RLR at the maximum volume control setting should be ≤ (equal or louder than) -2 dB.

2. For a desktop hands-free UE:
Where a user-controlled volume control is provided, the RLR shall meet the nominal value for at least one setting of the control. It is recommended that a volume control giving at least 15 dB increase from the nominal RLR (louder) is provided for hands-free units. This is to allow for increased acoustic noise level in the usage environment.
RLR at the maximum volume control setting should ≤ (equal or louder than) 1 dB.

Compliance shall be checked by the relevant tests described in TS 26.132.

NOTE: The target value for nominal RLR, as recommended in ITU-T G.111 Annex B – Table B.1 [4], lies between 1 and 3 dB. The higher RLR requirement of 5 dB for desktop hands-free is appreciative of the limitations in transducer output with current typical form factors.

7.2.4 Connections with hand-held hands-free UE

The nominal values of SLR/RLR to/from the POI shall be:

SLR = 13 ± 4 dB;

RLR = 9 +9/-7 dB.

Where a user-controlled volume control is provided, the RLR shall meet the nominal value for at least one setting of the control.

The value of RLR at the maximum volume control shall be ≤ (equal or louder than) 12 dB. As a performance objective it is recommended that the RLR at the maximum volume control setting is ≤ (equal or louder than) 2 dB.

Where a user-controlled volume control is provided, the RLR shall meet the nominal value for at least one setting of the control. It is recommended that a volume control range ≥ 15 dB be provided.

Compliance shall be checked by the relevant tests described in TS 26.132.

7.2.5 Connections with headset UE

The SLR and RLR should be measured and computed using methods given in ITU-T Recommendation P.380 [9]. This Recommendation currently gives a measuring technique for supra-aural earphone and insert type receivers. Study is continuing on other types of ear-pieces in ITU-T Study Group 12.

The nominal values of SLR/RLR to/from the POI shall be:

SLR = 8 ± 3 dB;

RLR = 2 ± 3 dB;

RLR (binaural headset) = 8 ± 3 dB for each earphone.

Where a user-controlled receiving volume control is provided, the RLR shall meet the nominal value for at least one setting of the control. When the control is set to maximum, the RLR shall not be ≤ (equal or louder than) -13 dB.

With the volume control set to the minimum position the RLR shall not be ≥ (equal or quieter than) 18 dB and shall not be ≥ (equal or quieter than) 24 dB for a binaural headset.

Compliance shall be checked by the relevant tests described in 3GPP TS 26.132.

7.2.5a Connections with headset UE in the presence of background noise

In the presence of background noise, the RLR at maximum volume control shall not be ≤ (equal or louder than) ‑13 dB.

Compliance shall be checked by the relevant tests described in TS 26.132.

7.2.6 Connections with electrical interface UE

7.2.6.1 Analogue connection

The nominal values of SJLR/RJLR to/from the POI shall be:

SJLR = 0 ± 3 dB;

RJLR = 0 ± 3 dB;

Where a user-controlled receiving volume control is provided, the RJLR shall meet the nominal value for at least one setting of the control. When the control is set to maximum, the RJLR shall not be ≤ (equal or louder than) -15 dB.

With the volume control set to the minimum position the RJLR shall not be ≥ (equal or quieter than) 16 dB.

Compliance shall be checked by the relevant tests described in 3GPP TS 26.132.

7.2.6.2 Digital connection

The nominal values of SJLR/RJLR to/from the POI shall be:

SJLR = 0 ± 3 dB;

RJLR = 0 ± 3 dB;

Requirements with different volume settings (other than nominal) are not applicable.

Compliance shall be checked by the relevant tests described in 3GPP TS 26.132.