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Ebertstraße 30aD-52134 HerzogenrathTel: +49 (0)2407-577-0Fax: +49 (0)2407-577-99E-mail: telecom@head-acoustics.deWEB: www.head-acoustics.de

HEAD acoustics GmbH

BGN Playback

MFE VI.1

Network Simulatore.g. CMU 200

RF cableconnection

USBPulse Channel

Balanced or LineIN 1 OUT 2

Speaker

600 Ohmor Unsymmetric

Connection

Mic1 2

Pulse OUT

Quiet Test Room(e.g. anechoic chamber)

Speech

DATA SHEET

DESCRIPTION

The tests implemented in HQS-mobilecover all conversational speech qual-ity aspects such as• delay measurements in sending and

receiving direction• objective speech quality assessment

under single talk conditions in sendingand receiving direction

• echo tests• detailed evaluation of quality during

double talk• quality of background noise transmis-

sion.In addition, recordings using real

speech under single talk, echo and doubletalk conditions are implemented in HQS-mobile. Apart from the measured parametersthese recordings also provide listening exam-ples which can be used for audio demonstra-tions.

For determination of the quality of back-ground noise transmission a standardizedarrangement consisting of four loudspeak-ers and one subwoofer is used in a separatetest room setup. It allows a close-to-real-ity noise playback and can be used forall types of background noise. In case noexternal background noise simulation systemis available, measurements using the artifi-cial mouth for playback are provided. Theyalso provide different background noises astest signals. Note that using the artificialmouth for background noise playback mayonly be a rough estimation of real soundfields.

Some of the measurements check the ana-lyzed results based on current ITU-T Recom-mendations or ETSI standards. The mainreferences for HQS-mobile are:• ITU-T P.50, Artificial Voice• ITU-T P.501, Test Signals for Use in

Telephonometry• ITU-T P.502, Objective analysis methods

for speech communication systems, usingcomplex test signals

• ITU-T P.340, Transmission Characteristicsand Speech Quality Parameters of Hands-free Telephones

OverviewSpeech quality assessment of mobile phonesis quite a challenge due to the various kindsof signal processing involved (e.g. noise re-duction algorithms, various kinds of speechprocessing and the transmission delay itself).All these aspects have a significant influenceon conversational speech quality. Currentstandards, however, are insufficient to as-sess all relevant parameters.To solve this problem HQS-mobile has beendeveloped by HEAD acoustics, providingcomprehensive tests for the analysis of

• Delay• Speech transmission quality• Echo• Quality during double talk• Quality of background noise

transmission• Tests according to Vodafone

Performance TSTFor manufacturers HQS-mobile providesobjective guidelines to optimize their mo-bile telecom products. For administrationsand network providers it offers selectioncriteria to ensure a high quality level.

HQS-mobile (Code 6776)HEAD Quality Standard

Speech Quality Assessment of Mobile Phones

• ITU-T P.862, Perceptual Evaluation ofSpeech Quality (PESQ)

• 3GPP TS 26.131, Terminal AcousticCharacteristics for Telephony Requirements

• 3GPP TS 26.132, Narrow band (3.1kHz) speech and video telephony terminalacoustic test specification

• ETSI EG 202 396-1, Speech quality per-formance in the presence of backgroundnoise; Part 1: Background noise simulationtechnique and background noise database

Other tests determine speech qualityparameters to analyze the performance ofthe equipment under test without referenceto ITU-T or ETSI standards. These measure-ments do not check requirements or limits,but can be used to optimize mobile phones.

Setup for measuring mobile phones using the communication analysis systemACQUA, the measurement frontend MFE VI and the artificial head HMS II.3

Example of TOSQA2001 analysis and TMOS calculation. Upper diagram: Time sequence(green: measured signal, gray: original signal). Lower diagram: TOSQA values for eachanalysis frame. Each maximum value is 100. Result window: TMOS value and other values(TOSQA value, Estimated Impairment Factor, Calculated Delay).

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represented by

APPLICATIONS

• Automated analysis of mobilephones

• Experimental development andoptimization of mobile phones withobjective evaluation of speech quality

MEASUREMENTS

The following is a complete list of all measure-ments included in HQS-mobile. In addition tothe manual, written explanations regardingthe required configurations are contained inthe measurement sequence.

Preparation measurements - delay• Measurements for calibration of Rohde &

Schwarz System Simulator CMU 200• System Delay sending / receiving / echo

Measurements in Receiving Direc-tion• Receiving Loudness Rating determined

with Artificial Voice (P.50, maximal andnominal volume) and Multisine

• Loudness Rating Stability• Idle channel noise with activation in send-

ing / in receiving• Frequency response with Multisine and

Artificial Voice (P.50) at 2N, 8N and 13Napplication force, transformation, 1/3oktave and 1/12 octave

• AGC tests (Automatic Gain Control) withcontinuous and sudden level variations

• Activation sensivity switch-on• Attenuation range: switch on / switch

over• Distortion 300-3400Hz with and without

activation signal• Optional: TMOS (objective MOS value

calculation with TOSQA2001) at differentapplication forces and output signal levels

Measurements in Sending Direction(Same measurements as in receiving direction;without measurements depending on applica-tion force and loudness). Additional measure-ment: minimum activation level.

Echo Measurements• Echo loss (G.122), single talk, at nominal

and maximal loudness setting• Convergence, level vs. time / spectro-

graphy• Echo level vs. time, signal level -5 dBm0 /

-25 dBm0• Spectral echo attenuation• Adaptation on AM/FM signals (P.501)• Echo attenuation during double talk

(P.340)

Measurements determining DoubleTalk Performance• Sensitivity double talk detection, sending• Simulated double talk (P.501, sending /

receiving)• Attenuation range double talk (P.340,

sending / receiving)

Measurements determining Qualityof Background Noise Transmission(for any kind of noise using an ex-ternal background noise playback)• D-Value and ANR (G.111)• Quality of background noise with CS

signal at far end / at near end• Analysis of generated Comfort Noise

Example of application force dependent acoustical leakage behavior analysis. Severalfrequency response measurements were carried out with several SMDs and varying applicationforce between mobile phone and artificial ear. All resulting curves can be shown in onediagram using the multi-select feature and the 'Result Diagram' tab of ACQUA.

Viewer mode„Result Diagram“activated

Multiple selectionof results

Application force dependentacoustical leakage behavior

regarding level, spectral characteristicsand hearing model based analysis of time-variant and/or spectral components (op-tional with “Relative Approach”)

Alternatively, these measurements can becarried out using the artificial mouth for play-back. These modified tests provide a station-ary type of noise (car noise) and a non-sta-tionary, more realistic type of noise (pubnoise).

Speech Recordings• Speech - single talk (sending / receiving /

echo)• Speech - double talk (sending / receiving)

Tests according to Vodafone Per-formance TST

These tests basically contain a subset ofthe measurements described above. Theyare also subdivided in Sending DirectionMeasurements, Receiving Direction Mea-surements, Double Talk Performance, EchoMeasurements, Background Noise Transmis-sion and Speech Recordings. Additional mea-surements are provided to evaluate one-waylistening speech quality using TOSQA2001and PESQ algorithms in real cellular networkswith different AMR codec bitrates.

SYSTEM REQUIREMENTSHQS-mobile requires the following sys-

tem components:

• ACQUA Communication Analysis Systemas one of the following versions:- Standard (Code 6810)- Standard Workplace (Code 6830, for analysis only)- Compact Systems

• HMS II.3 HEAD Measurement System(Code 1230)

• HHP II.1 Handset Positioner (Code1377)

• MFE VI.1 Measurement Frontend (Code6462); alternatively: MFE VI Measure-ment Frontend (Code 6460) with HMAIV Mouth Amplifier (Code 1411) andHLC I Level Converter (Code 1412, ifrequired)

• ISDN Tester, e.g. Aethra D2000 Pro

OPTIONS

• HAE-BGN Background Noise Simulation(Code 6971, required for backgroundnoise tests)

• TOSQA2001 TelecommunicationsObjective Speech Quality Assessment(ACOPT 10, Code 6820, required forTMOS tests)

• PESQ Perceptual Evaluation of SpeechQuality according to ITU-T P.862 (ACOPT16, Code 6836, required for Vodafonetests)

• “Relative Approach” Hearing modelbased analysis of time-variant or spectralcomponents (ACOPT 17, Code 6839,required for background noise tests)