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Introduction
Functionality
Scientific Background
AQuA Command Line parameters
AQuA Command Line usage
Analysis of possible reasons for voice and audio quality loss
Visualizing signals spectrum for analysis
AQuA Online
AQuA Benefits

AQuA – Audio Quality Analyzer page
Download AQuA Manual as PDF

AQuA Command Line usage

Most of our customers represent the following business segments:

• VoIP service providers
• Audio and web conferencing providers
• Unified communications
• Solution providers for telecom

AQuA helps telecom business to solve a wide range of tasks:

• test conference bridges quality when dialing from different locations
• monitor quality live on a conference bridge to detect who from the conference participants f.e. introduces more noise
• monitor quality to certain destinations depending on network load
• monitor quality at different terminations by end-to-end testing with termination’s echo server
• test quality in converged networks (f.e. Mobile-VoIP)
• device testing in noisy environment

In all cases AQuA is the means for end-to-end intrusive (active) testing, which involves a reference audio file compared to the one passed through a network, device or any other environment that may introduce degradation (f.e. a voice codec).

In order to show how AQuA perfoms perceptual voice quality assessment we are going to use WAV files one can download from Microtronix web site (http://www.microtronix.ca/pesq.html). However, one can use any audio files within AQuA Wideband or those that are recorded at 8Khz sampling and are 16 bit mono (in case of AQuA Voice).

Compare two audio files and learn about reasons for voice quality loss

To compare two audio files in AQuA Command Line version when one is interested to get extensive feedback from the software we suggest to invoke AQuA in the following manner:

aqua-wb.exe tst.lic -mode files -src file Or272.wav -tstf Dg002.wav -acr auto -npnt auto -miter 1 -ratem %mp -fau log.txt

As result you will received the following output:

Sevana Audio Quality Analyzer – AQuA-Wideband v.5.3.11.712.
Copyright (c) 2009 by Sevana Oy, Finland. All rights reserved.
—————————————————————
File Quality is
Percent value 39.31
MOS value 2.23
PESQ value 2.61

Thus one can see that file comparison gives only 36.11% of similarity what corresponds to 1.49 MOS and about 2.56 PESQ. By the way, this is an example of when AQuA does detect voice quality loss and PESQ does not (please read more details about this test case on Microtronix page).

After test was executed log.txt file contains quantitative reasons for voice quality loss:

Source SNR : 63.160200.
Degradated SNR : 71.187480.
Duration distortion.
Audio stretching corresponds to 1.41 percent.

Delay of audio signal activity.
Signal delayed by 100.000000 ms.
Audio signal activity mistiming (unsynchronization) is 1.25 percent.

Corrupted signal spectrum.
Overall spectral energy distortion approaches 62.18 %
Vibration along the whole spectrum [-19.73, 42.45] %

Significant distortion in low frequencies band.
Energy distortion approaches 32.27 %
Spectrum vibration in low frequency band [-16.91, 15.36] %

Significant distortion in medium frequencies band.
Energy distortion approaches 27.10 %
Amplification approaches 24.29 %

Compare two audio files and receive audio quality score

In case we like to simply compare two audio files and get feedback on how similar they are quality wise we suggest invoking AQuA in the following manner:

aqua-wb.exe tst.lic -mode files -src file Or272.wav -tstf Dg001.wav -acr auto -npnt auto -miter 1 -ratem %mp

Result will be:

Sevana Audio Quality Analyzer – AQuA-Wideband v.5.3.11.712.
Copyright (c) 2009 by Sevana Oy, Finland. All rights reserved.
—————————————————————
File Quality is
Percent value 92.08
MOS value 4.89
PESQ value 3.34

or invoking it for the other degraded file:

aqua-wb.exe tst.lic -mode files -src file Or272.wav -tstf Dg002.wav -acr auto -npnt auto -miter 1 -ratem %mp

Sevana Audio Quality Analyzer – AQuA-Wideband v.5.3.11.712.
Copyright (c) 2009 by Sevana Oy, Finland. All rights reserved.
—————————————————————
File Quality is
Percent value 39.31
MOS value 2.23
PESQ value 2.61

Adapting AQuA to actual environment

AQuA parameters have pre-set values by default, however, in some cases it is required to adapt the algorithm to actual environment, which is network, device settings, or specific codec. Majority of our customers don’t require adjusting AQuA parameters, but in some cases software tuning makes test results more consistent. There is no common case when it’s 100% required, but some of our customers mentioned that when doing tests in mobile networks, or VoIP-mobile this tuning gives better scores.

In case your tests show unexpected results means that AQuA engine or VAD may need tuning. We suggest to try playing around with these parameters first:

• -npnt
– This parameter sets the amount of linking points required to catch different “holes”
inside the signal. By default the value is 5.
• -miter
– Sets amount of voice activity detector frames that are used during smoothing. By default
it’s 5. This is required to smooth the detector’s vibration.

For example:

aqua-wb.exe tst.lic -mode files -src file Or272.wav -tstf Dg002.wav -acr auto -npnt 1 -miter 5 -ratem %mp

Result is:

Sevana Audio Quality Analyzer – AQuA-Wideband v.5.3.11.712.
Copyright (c) 2009 by Sevana Oy, Finland. All rights reserved.
—————————————————————
File Quality is
Percent value 39.73
MOS value 2.25
PESQ value 2.61

or invoking it for the other degraded file:

aqua-wb.exe tst.lic -mode files -src file Or272.wav -tstf Dg001.wav -acr auto -npnt 1 -miter 5 -ratem %mp -fau log.txt

Sevana Audio Quality Analyzer – AQuA-Wideband v.5.3.11.712.
Copyright (c) 2009 by Sevana Oy, Finland. All rights reserved.
—————————————————————
File Quality is
Percent value 90.22
MOS value 4.82
PESQ value 3.23

In fact this result is much closer to what one would hear, however, the file was degraded. One can find the reasons for voice quality loss in the log.txt file, e.g.:

Source SNR : 63.160200.
Degradated SNR : 60.847082.
Duration distortion.
Audio stretching corresponds to 14.15 percent.

Advancing of audio signal activity.
Signal advances the original by -400.000000 ms.

Audio signal activity mistiming (unsynchronization) is 1.34 percent.

Synchronizing original and test files using AQuA 5.x

In many cases when monitoring voice quality in real environment one receives degraded file from the netwok containing pauses before and/ or after the actual audio. Let’s consider an example received from one of our customers while doing voice quality monitoring in a mobile network. Initial audio is a male voice pronouncing a phrase in English language with the following wave form:

This audio is sent over a mobile network and then recorded back, but due to delays before the call is established and after hang-up degraded file has delays in the beginning and end of the audio:

Further more, if one zooms into the “silence” he will realize that it contains noise:

According to AQuA algorithms introduction of silence or noise leads to quality degradation, and taking into account that establishing a test call as well as then detecting disconnect tone may take even a couple of seconds, this may significantly decrease the final quality score.

In order to trim irrelevant parts of the test signal in the beginning and end of the degraded file one just needs to invoke AQuA with a -trim parameter:

aqua-wb.exe tst.lic -mode files -src file male.wav tstf male_5s_delay_5s_end_-36db_whitenoise.wav -acr auto -npnt auto -miter 1 -trim r 5 -ratem %mp -fau log.txt

AQuA output will be:

Sevana Audio Quality Analyzer – AQuA-Wideband v.5.3.11.712.
Copyright (c) 2009 by Sevana Oy, Finland. All rights reserved.
—————————————————————
File Quality is
Percent value 74.59
MOS value 3.98
PESQ value 2.94

or one can use another option as described above:

aqua-wb.exe tst.lic -mode files -src file male.wav -tstf male_5s_delay_5s_end_-36db_whitenoise.wav -acr auto -npnt auto -miter 1 -trim a 45 -ratem %mp -fau log.txt

AQuA output will be:

Sevana Audio Quality Analyzer – AQuA-Wideband v.5.3.11.712.
Copyright (c) 2009 by Sevana Oy, Finland. All rights reserved.
—————————————————————
File Quality is
Percent value 75.28
MOS value 4.02
PESQ value 2.96

However, in order to be absolutely sure that the trimming works properly let’s test it with an artificially created file containing silence:

aqua-wb.exe tst.lic -mode files -src file male.wav -tstf male_5s_delay_5s_beginning.wav -acr auto -npnt auto -miter 1 -trim a 45 -ratem %mp -fau log.txt

Sevana Audio Quality Analyzer – AQuA-Wideband v.5.3.11.712.
Copyright (c) 2009 by Sevana Oy, Finland. All rights reserved.
—————————————————————
File Quality is
Percent value 100.00
MOS value 5.00
PESQ value 4.50

and another one with silence in the beginning and the end of the file:

aqua-wb.exe tst.lic -mode files -src file male.wav -tstf male_5s_delay_5s_end.wav -acr auto -npnt auto -miter 1 -trim a 45 -ratem %mp -fau log.txt

Sevana Audio Quality Analyzer – AQuA-Wideband v.5.3.11.712.
Copyright (c) 2009 by Sevana Oy, Finland. All rights reserved.
—————————————————————
File Quality is
Percent value 100.00
MOS value 5.00
PESQ value 4.50

To AQuA Manual Page (3/7)

To AQuA Manual Page (5/7)

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