Überblick der bisher bearbeiteten themen - tu-ilmenau.de · synthesis to 22.2 (2008) background:...

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Überblick der bisher bearbeiteten Themen

2006 - 2013

Judith Liebetrau

Ilmenau

20.10.2014

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Perceptual Evaluation of 5.1 Downmix Algorithms (2006)

Today:

Stereo in wide use

5.1 formats spreading in the home

Production in both formats is expensive

Cheaper solution

Production in 5.1 and automatic down‐mix

How good are the algorithms ?

How to measure quality ?

Artistic Mixes ?

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Experimental Design – Alternatives

ITU‐R BS.1116 (tripple stimulus with hidden reference)

only valid for small impairments

ITU‐R BS.1534 (multi stimulus with hidden reference and anchors)

Valid for intermediate quality

But… Artistic mix might sound very different

What is the reference ?

ITU‐R BS.1284

(Paired comparison)

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7‐point comparison scale:

System 1 compared to

system 2 is

Setup:

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Perceptual Evaluation of 5.1 Downmix

Algorithms (2006)

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Perceptual Evaluation of 5.1 Blind Up-mix Algorithms

(2007)

5.1 formats spreading in the home: Broadcasting in 5.1 formats

5.1 formats enable increased sweet spot

Old content still in mono or stereo

Customers want to play their old content (CD, vinyl disc) in 5.1 format

Even new content sometimes stereo

Customers complain Broadcasters have to react

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(2007)

Solutions:

For broadcasting/new content:

Production in stereo and 5.1 (expensive)

Production in 5.1 and automatic down‐mix (only for new content)

Blind Up‐mix from Stereo to 5.1

How good are algorithms for up‐mix ?

How to measure quality ?

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(2007)

Experimental Design ‐ Alternatives:

ITU‐R BS.1116 (tripple stimulus with hidden reference)

only valid for small impairments

ITU‐R BS.1534 (MUSHRA)

Quality might be better than original

Experiment derived from MUSHRA

New Scale (Values ‐50 to +50)

Loop mode and near instantaneous switching

Reduce scale to the point “equal” and indication of direction

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(2007)

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Localization in Spatial Audio ‐ from Wave Field

Synthesis to 22.2 (2008)

Background:

Several approaches for realistic surround sound

Localization influences perception of quality

Localization resolution

Highest with infinite number of loudspeakers

Complex software model for reproduction

Increasing complexity of sound system = increasing costs

low complexity/costs required!

Goal:

Compromise between localization resolution and complexity

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Comparison of Sound Systems (“High resolution” – “low resolution”)

Localization horizontal and vertical layer

Steadiness of sound sources

Dimension of sound sources

Dependence on listening position

Development…

… of a listening test procedure, which provides the required information

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Combination WFS ring, WFS ceiling, 3D-Audio-System (22.2)

Dimension 3.85m x 5.60m x 2.40m

158 LS + 6 Subs

Acoustical treatment of room

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Training Session

Familiarization with all stimuli under test

Grading Phase

3 positions simultaneously

Judgment on paper

Stimulus played back twice

Decision where it was localized

Character of sound source (1) defined (4) diffuse

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Psychoakustische Banbreitenerweiterung (2009)

Kleine Lautsprecher

hohe Grenzfrequenz

Tieffrequente Anteile fehlen

Algorithmen zur psychoakustische Bandbreitenerweiterung

Frequenzverdopplung

Differenzton

Missing Fundamental (Residualton)

Originalsignal (wenig Tiefton) und bearbeitete Signale

Frage: Welches hat mehr Tieftonanteile?

Modifizierter MUSHRA

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AV discrepancy & the influence in vertical sound source

localization (2011)

Influence: Audio perception by vision

Ventriloquism‐effect

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Thema 1: Musik und Emotionen (2012)

Gewünscht: Messung von Emotionen während Musikhören

Problem der Beeinflussung von Probanden

Testmethode Free Choice Profiling:

Vorteil: Verwendung eigenes Vokabular

Berechnung gemeinsamer Wahrnehmungsraum

Pilotexperiment: Klassifikation von Tönen nach emotionalen Gehalt mittels

(FCP)

Wahrnehmungsraum erstellt

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Dimensionen aus denen sich Emotionen zusammensetzen

Valence (positiv - negativ)

Arousal (hoch – niedrig)

Überprüfung wie gut FCP funktioniert

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Ranking der Items entlang der Dimensionsachsen

40 Vergleichstest (4 Gruppenn a 10 Vergleiche)

<=> emotionaler Charakter (Valenz/Arousal)

kein Anker

keine quantifizierbare Skala

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Thema 2: PERCEPTION OF APPARENT SOURCE WIDTH

AND LISTENER ENVELOPMENT IN WAVE FIELD

SYNTHESIS (2012)

Überprüfung der 2 Parameter Apparent source width (ASW) und Listener

envelopment (LEV

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Thema 2: PERCEPTION OF APPARENT SOURCE WIDTH

AND LISTENER ENVELOPMENT IN WAVE FIELD

SYNTHESIS (2012)

Test method:

Paired comparison

Is ASW smaller/ wider compared to the reference

Is LEV higher/ lower compared to the reference

Trainingsession before test:

presenation of maximum characteristics

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LOCALIZATION OF AUDIO OBJECTS IN MULTI-

CHANNEL REPRODUCTION SYSTEMS: MPEG-H (2013)

Spatial audio systems should create natural sound field

Perception of loudspeaker could influence this perception

Design of a localization test:

Without visual cues

Blindfolded

Moveable listening cubical

Different listening positions

Design of a Test GUI

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Und nun? Ideen für Tests WS 2014/2015

Lärmbewertung und Lärmmessung

Ermittlung von psychoakustischen Größen in der Wahrnehmung von

Wohlklang

Fehler bei der Auralisation von Arraydaten

Einfluss der Skalen auf die Bewertung bei Hörtests

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Es lärmt….

Lärm/Geräuschbewertung und -messung

Bewertung der Soundscape um einen herum (Café, Park, Hörsaal etc.)

Was muss man da alles aufnehmen?

Woraus setzt sich Lärmempfinden zusammen?

Ermittlung von psychoakustischen Größen in der Wahrnehmung von

Wohlklang

„objektive Maße“ Rauigkeit, Schärfe etc. (Signalanalyse)

Wie weit korrelieren diese mit subjektiver Empfindung?

Wie kann ich denn den Wohlklang messen?

Aus welchen Parametern setzt sich Wohlklang zusammen?

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Skalen und deren Auswirkung

Denkbar als alleinstehendes Thema oder Add-on zu anderen Themen

Wie unterscheiden sich die Ergebnisse bei Verwendung

Kontinuierliche vs. diskrete Skala

Radio buttons vs. Drop-down menüs

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