3 Definitions, symbols and abbreviations

26.1313GPPRelease 18RequirementsTerminal acoustic characteristics for telephonyTS

3.1 Definitions

For the purposes of the present document the terms narrowband, wideband, super-wideband and fullband refer to signals associated with the corresponding operating modes of the speech codecs specified in TS 26.132.

For the purposes of the present document, the terms dB, dBr, dBm0, dBm0p and dBA, shall be interpreted as defined in ITU-T Recommendation B.12 [2]; the term dBPa shall be interpreted as the sound pressure level relative to 1 pascal expressed in dB (0 dBPa is equivalent to 94 dB SPL).

The overload point (maximum load capacity) is for the purposes of this document defined as the RMS level of a digital representation of a full-scale pure tone at the input of the speech encoder. The overload point is defined at 3,14 dBm0 for AMR, AMR-WB and EVS speech codecs.

A 3GPP softphone is a telephony system running on a general purpose computer or PDA complying with the 3GPP terminal acoustic requirements (TS 26.131 and 26.132).

For the purposes of the present document the term clock skew is defined as the difference between the clock of the device under test (C_DUT) and the clock of the reference client (C_REF). The skew of C_DUT relative to C_REF is defined in parts per million (PPM) as: (C_DUT -C_REF).10⁶/ C_REF.

For the purposes of the present document, the term electrical interface is defined as an analogue or digital access to a UE, which allows injecting and capturing signals electrically instead of through an acoustical interface. The interface can be either analogue (wired) or digital (wired or wireless). The purpose of this interface is to connect a separate device (typically a headset), which provides a receiver and transmitter for telephony.

3.2 Abbreviations

For the purposes of the present document, the following abbreviations apply:

ADC Analogue to Digital Converter

AMR Adaptive Multi Rate

DAC Digital to Analogue Converter

DAI Digital Audio Interface

DRP Eardrum Reference Point

DTX Discontinuous Transmission

EEC Electrical Echo Control

EL Echo LossERP Ear Reference Point

EVS Enhanced Voice ServicesHATS Head and Torso Simulator

G-MOS-LQO_n Global (Overall) Mean Opinion Score – Listening Quality Objective – Narrowband

G-MOS-LQO_w Global (Overall) Mean Opinion Score – Listening Quality Objective – Wideband

G-MOS-LQO_fb Global (Overall) Mean Opinion Score – Listening Quality Objective – Fullband

IMS IP Multimedia Subsystem

LSTR Listener Sidetone Rating

LTE Long Term Evolution

MRP Mouth Reference Point

MTSI Multimedia Telephony Service for IMSOLR Overall Loudness Rating

N-MOS-LQO_n Noise (Background) Mean Opinion Score – Listening Quality Objective – Narrowband

N-MOS-LQO_w Noise (Background) Mean Opinion Score – Listening Quality Objective – Wideband

N-MOS-LQO_fb Noise (Background) Mean Opinion Score – Listening Quality Objective – Fullband

NR New Radio

PCM Pulse Code Modulation

PDA Personal Digital Assistant

POI Point of Interconnection (with PSTN)

PSTN Public Switched Telephone Network

RLR Receive Loudness Rating

S-MOS-LQO_n Speech Signal Quality Mean Opinion Score – Listening Quality Objective – Narrowband

S-MOS-LQO_w Speech Signal Quality Mean Opinion Score – Listening Quality Objective – Wideband

S-MOS-LQO_fb Speech Signal Quality Mean Opinion Score – Listening Quality Objective – Fullband

SLR Send Loudness Rating

STMR Sidetone Masking Rating

SS System Simulator

TX Transmission

UE User Equipment

UMTS Universal Mobile Telecommunications System

UPCMI 13-bit Uniform PCM Interface

WLAN Wireless Local Area Network