Apparent source width: Difference between revisions

Revision as of 16:42, 7 July 2018

Revision as of 16:43, 7 July 2018

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'''Apparent Sourcesource Widthwidth (ASW)''' is the audible impression of a spatially extended sound source. Physically, this psychoacoustic impressions results from sound radiation characteristics and room acoustical properties. Wide sources are desired by listeners of music. Apparent source width affects the perceived sound of [[acoustic music|unplugged]] [[concert]]s of [[art music]], [[opera]], [[classical music]], [[historically informed performance]] and [[contemporary classical music]], as well as concerts that use [[live event support]], like [[live sound mixing]], [[sound reinforcement system]]s or a [[public address system]], like [[popular music]], [[rock music]], [[electronic music]] and [[musical theatre]]. Research concerning the ASW comes from the field of [[room acoustics]], [[architectural acoustics]] and [[auralization]] as well as [[musical acoustics]], [[psychoacoustics]] and [[systematic musicology]].

==Physics and Perceptionperception==

Apparent source width is the aurally perceived extent of a sound source. Sometimes, it is defined as the impression that a source sounds larger than its optical size<ref name="blau">{{cite journal |last1=Blau |first1=Matthias |title=Correlation of apparent source width with objective measures in synthetic sound fields |journal=Acta Acustica United With Acustica |date=2004 |volume=90 |issue=4 |page=720 |url=http://www.ingentaconnect.com/content/dav/aaua/2004/00000090/00000004/art00015# |accessdate=31 May 2018}}</ref>. The impression results from several auditory cues, which are affected by sound radiation characteristics of the source itself and by characteristics of the room.

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<ref name="ziemer">{{cite book|last1=Ziemer|first1=Tim|editor1-last=Schneider|editor1-first=Albrecht|title=Studies in Musical Acoustics and Psychoacoustics|doi=10.1007/978-3-319-47292-8_10|date=2017|publisher=Springer|___location=Cham|isbn=978-3-319-47292-8|pages=299-340|url=https://link.springer.com/chapter/10.1007/978-3-319-47292-8_10|accessdate=25 May 2018|chapter=Source Width in Music Production. Methods in Stereo, Ambisonics, and Wave Field Synthesis}}</ref>. Unlike hypothetical [[Point source#Sound|monopole source]] musical instruments radiate their sound not evenly in all directions. Rather the overall [[Amplitude|volume]] and the [[frequency spectrum]] differ in each direction, referred to as [[sound radiation characterisitcs]] or radiation patterns<ref name=ziemer/> <ref name="ziemerdiss">{{cite thesis|type=PhD|doi=10.13140/RG.2.1.1997.9769|last1=Ziemer|first1=Tim|title=Implementation of the Radiation Characteristics of Musical Instruments in Wave Field Synthesis Applications|date=2015|publisher=Univ. Diss.|___location=Hamburg|url=http://ediss.sub.uni-hamburg.de/volltexte/2016/7939/|accessdate=25 May 2018}}</ref><ref name="bader">{{cite journal|last1=Bader|first1=Rolf|title=Radiation characteristics of multiple and single sound hole vihuelas and a classical guitar|journal=The Journal of the Acoustical Society of America|date=2012|volume=131|issue=1|pages=819-828|doi=10.1121/1.3651096|url=https://asa.scitation.org/doi/10.1121/1.3651096|accessdate=25 May 2018}}</ref>. These may create incoherent ear signals and, consequently, the impression of a wide source. The sound radiation characteristics of musical instruments are typically given as [[radiation pattern]] in a two- to three-dimensional [[polar coordinate system]]<ref name="meyer">{{cite book|last1=Meyer|first1=Jürgen|doi=10.1007/978-0-387-09517-2|title=Acoustics and the Performance of Music. Manual for Acousticians, Audio Engineers, Musicians, Architects and Musical Instrument Makers|date=2009|publisher=Springer|___location=Bergkirchen|isbn=978-0-387-09516-5|edition=Fifth Edition|url=https://link.springer.com/book/10.1007/978-0-387-09517-2|accessdate=25 May 2018}}</ref><ref name="patynen">{{cite journal|last1=Pätynen|first1=Jukka|last2=Lokki|first2=Tapio|title=Directivities of Symphony Orchestra Instruments|journal=Acta Acustica United With Acustica|date=2010|volume=96|issue=1|pages=138-167|doi=10.3813/aaa.918265|url=https://doi.org/10.3813/AAA.918265|accessdate=25 May 2018}}</ref><ref name="ziemerj">{{cite journal|last1=Ziemer|first1=Tim|last2=Bader|first2=Rolf|title=Psychoacoustic Sound Field Synthesis for Musical Instrument Radiation Characteristics|date=2017|volume=65|issue=6|pages=482-496|doi=10.17743/jaes.2017.0014|url=http://www.aes.org/e-lib/browse.cfm?elib=18781|accessdate=25 May 2018}}</ref><ref name="zotter">{{cite thesis|type=PhD||institution=University of Music and Performing Arts Graz|last1=Zotter|first1=Franz|title=Analysis and Synthesis of Sound-Radiation with Spherical Arrays|date=2009|___location=Graz|url=https://iem.kug.ac.at/en/projects/workspace/projekte-bis-2008/dsp/analysis-and-synthesis-of-sound-radiation-with-spherical-arrays.html|accessdate=25 May 2018}}</ref>.

==Subjective Roomroom Acousticsacoustics==

The apparent source width and other subjective sound properties in many concert halls have been rated by experts, like [[conductor]]s and [[Music criticism|music critics]]. Together, apparent source width and listener envelopment are the most important contributors to the spaciousness impression of a concert hall which is the most important contributor to the quality ratings of concert halls<ref name=beranek />.

In the field of subjective [[room acoustics]] the sound radiation characteristics are ignored and the apparent source width is explained by means of objective measures of room [[impulse response]]s, like the [[binaural quality index]], the [[lateral energy fraction]] and the early [[sound strength]]<ref name=beranek /><ref name=ziemer /><ref name=blau />. These tend to correlate with the subjective expert ratings. Accordingly, early, incoherent, lateral reflections together with a high [[loudness]] of low frequencies in the early reflections of the room reverberation increase the appatent source width and thus the overall spaciousness and quality of a concert hall. This knowledge is used in [[architectural acoustics]] to design a concert hall that exhibits the desired acoustical properties.

==Music Productionproduction==

In [[audio mastering]] and [[sound recording and reproduction]] a major task of the [[recording studio]]`s [[audio engineer]]s and [[record producer]]s is to make musical instruments sound huge<ref name="huge">{{cite book|last1=Levinit|first1=D.J.|editor1-last=Greenbaum|editor1-first=K.|editor2-last=Barzel|editor2-first=R.|title=Audio Anecdotes|publisher=A K Peters|___location=Natick|volume=vol. I|isbn=1568811047|pages=147-158|chapter=Instrument (and vocal) recording tips and tricks}}</ref>. The increase of apparent source width is as important as [[Equalization (audio)|spectral balancing]] and [[dynamic range compression]] <ref name="mastering">{{cite book|last1=Kaiser|first1=C.|title=1001 Mastering Tipps|date=2013|publisher=mitp|___location=Heidelberg|page=23,40}}</ref>.

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==Related Soundsound Impressionsimpressions==

Several subjective sound impressions are closely related to apparent source width. [[Reverberance]] refers to the impression that spatially and temporally distributes sounds blend du to reverberation. [[Liveness]] is the the impression that the room contributes more than just repititions of direct sound. A live concert sound better in a reverberant than in a dead or dry hall. In intimate halls instruments sound near and the hall sounds small. [[Listener envelopment]] is the impression that the listener takes a bath in sound, i.e., that sound comes from all over the place. [[Spaciousness]] is a term that summarizes apparent source width and listener envelopment.<ref name=beranek/>