Sound Timbre and Information Transfer

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Sound follows function
Sound communication and
the relevance of timbre.

Lecturer: Rainer Hirt & Kai Bronner (audio-branding.de)

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01 Acoustic signs and its functions
02 Overview ongoing
Functional-Timbre-Study (FTS)

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01 Acoustic signs and its functions

Signs?

A. Basics B. Study C. Results

Signs!
A sign is a stimulus pattern that has a meaning.

A sign stands for something else.


Semiotics: Theory of signs

Index
An „Index“ is deﬁned by some sensory feature
(something directly visible, audible, smellable, etc)
that is connected to it.



Icon
An icon is a pattern that physically resembles
what it „stands for“.



Symbol
Symbols are arbitrary and unmotivated, reliant on
conventional usage to determine meaning.


Acoustic signs?


Acoustic signs!
Index
Icon
Symbol
Index becomes Icon

Symbol becomes Icon


Applications of
acoustic signs

Corporate Sound
Cultural

Auditory-User-Interface
Auditory Display Audiﬁcation


Basic design-approaches of
acoustic signs:

Auditory icons
Auditory symbols
Auditory symcons (Mixed)


Ambition & research questions
1. Appropriateness of Auditory icons/symbols and symcons for the transfer of
information-functions:
–> Advice
–> Warning
–> Emergency

2. Effects of the mixture of icon and symbol („auditory symcon“)

3. Advantages of acoustic signs for „public-user-interfaces“


Analysis of a situation
– Talks with manfactures and customers (Höft-Wessel, ICA, DB)

– Secondary literature

– Preliminary study (semantic ﬁeld-analysis)


Study object
Ticket machine


Study design
Study method: Descriptive study

Survey sample size : N=22
Age average: 35 years
Women/Men: 10/12


Lab set-up
> Lectern (Terminal-simulation)
> Table-PC (Touchpad)
> Headphone


Stimuli
lic conic
nic ymbo ym
ico s s
Advice: „Ticket ready for collection“ 1 2 3

Advice: „Money ready for collection “ 1 2 3

Warning: „Timeout“ 1 2 3

Emergency: Deterrence 1 2 3

Context-Soundscape (Trainstation)


Evaluation methods
Semantic differential


Evaluation methods
Categorical scaling


Evaluation methods
Categorical scaling
Response time measurement


Evaluation methods
Categorical scaling
Participant observation


Evaluation methods
Categorical scaling
Participant observation
Association analysis


1. Appropriateness of Auditory icons/symbols and symcons for the transfer of
information-functions:
–> Advice
–> Warning
–> Emergency

2. Effects of the mixture of icon and symbol („auditory symcon“)


Auditory Icon Auditory Symbol Auditory Symcon

Advice

Warning

Emergency

Funtion(intention) partially transferred

Funtion(intention) transferred

Funtion(intention) not transferred or false interpretation




The meaning of function of acoustic signs is comprehended intuitively.


Further investigations
The study reveals amongst others, that further investigation on the acoustical
parameter „timbre“ is required.

In the literature there is nearly no advice for selecting timbre according an
information-function.

Thus, an ongoing study that addresses the perception of timbre is topic of the
further presentation.


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02 Timbre and function

A. Timbre: deﬁnition & properties
B. Sound perception
C. Study design

A. Timbre: deﬁnition & properties B. Sound perception C. Study design

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A. Timbre: deﬁnition & properties

Timbre – what? Deﬁnition
Deﬁnition (American Standards Association 1960)
Timbre is that attribute of auditory sensation in terms of which
a listener can judge that two sounds similarly presented and having
the same loudness and pitch are dissimilar.

A B


Timbre properties
Verbal descriptions
overtone constellation: bright, dark, mellow, hollow, pure
noise content: raspy, breathy, hoarse
attack: smooth, abrupt, sharp, gentle, easing

Relations
pitch - frequency
loudness - amplitude
timbre - multiple interacting acoustic factors


Timbre properties
H. Fletcher (1934)
Experiments show that a simple one-to-one relationship does not exist between
the two sets { loudness, pitch, timbre } and { sound intensity, fundamental
frequency and overtone structure }

sound intensity loudness

fundamental frequency pitch

overtone structure timbre


Timbre properties
More than one dimension:
multidimensionality
Erickson (1975)
Clearly timbre is a multidimensional stimulus: it cannot be correlated with
any single physical dimension.

Plomp (1982)
Sounds cannot be ordered on a single scale with respect to timbre.
Timbre is a multidimensional attribute of the perception of sounds.


Multi-Dimensionality-Scaling
MDS
MDS studies reveal perceptual dimensions correlated with acoustic
parameters corresponding to spectral, temporal and spectrotemporal
properties of the sound events.

– experiments with paired sound stimuli
– rating of similarity
– axes corresponding to timbre‘s main perceptual dimensions –> timbre space


Dimensions
Dimension I = brightness
Low brightness : french horn and cello
Dimension I
High brightness : oboe, muted trombone

Dimension II = spectral flux
High synchronicity and low fluctuation :
clarinet, saxophone
Low synchronicity and high fluctuation :
flute, violoncello

Dimension III = attack quality
III
Dimension II ion
More transients : strings, flute
imens
D
Fewer transients : brass, bassoon


Timbre dimensions and
related parameters
Across studies, several acoustic/physical parameters corresponding
to timbre dimensions were found:

– Spectral centroid – Spectral ﬂux
– Spectral deviation – Pitch strength
– Spectral density – Attack synchronity
– Attack time – Attack centroid
– Decay time – Noisiness
–Amplitude envelope ...


Timbre and psychoacoustic
properties
Interview Dr. Gerhard Thoma, chief sounddesigner BMW:
(http://www.goethe.de/ges/wrt/dos/aut/sou/de2169434.htm , 10/2007)

(...) There are sets of regression equations that help calculating/predicting
a desired sound perception, for example a sporty sound:

a x sharpness + b x roughness + c x ﬂuctuation strength, … = sportiness.!!

About 80 % of people will evaluate the sound in terms of sportiness.
But:„acid test“in driving situation (context) = proof of validity!(...)


Psychoacoustic properties and
cognitive/affective evaluation
– simple psychoacoustic parameters only refer to ﬁxed relations of perception and
instantaneous stimuli (Haverkamp 2007)

– psychoacoustics are only capturing parts of human sound perception, largely
excluding important affective + cognitive evaluation (Vjästfall/Kleiner 2002)

– any endeavour to evaluate (product) sounds by psychoacoustics solely will fail in
the end (Blauert/Jekosch 1997)


Sound perception:
target groups/context
– individual differences of preferences of particular groups of people for
qualitatively different product sounds
– no simple „universal“ manipulation that will have the same effect on the
sound quality of products (Spence & Zampini 2006)

–> target groups (age, cultural background, milieus/lifestyle) have to be taken
into account
–> it is important to consider the kind/type of product = context


Emotional evaluation and
functional content
Activation
tense alert
Model of affective circumplex
Emergency
nervous excited
(Russell, 1980)
elated
stressed Warning

upset happy
Advice
Unpleasant Pleasant
Conﬁrmation
contented
sad

serene
depressed

relaxed
bored

Deactivation


Sound perception:
evaluation of sound (timbre)
To be taken in account:
– psychoacoustic properties of sound
– learned associations
– cultural background and personal experiences (target group)
– context: mood of subjects, expectations, situation
– inﬂuence from other modalities (vision, touch,...)


Functional Timbre Study
(„sound-colour the Gestalt“)
VARIABLES (TIGA)

Independent:
Timbre T
Gestalt G [pitch contour, rhythm, tone duration]

Dependent:
Information-function I [function, e.g. emergency, warning, advice/conﬁrmation]

Attribution A [emotional/affective evaluation: warm, harsh, sharp,...]


Sound-colour the Gestalt
Approach:
sound-colour T the Gestalt G and examine evaluations of subjects
regarding information-function I and attribution A


Example of stimuli
Same Gestalt, different timbre

A B


Study Design
Step 1: free association task
3 Gestalt x 8 Timbre = 24 sound-stimuli are evaluated by subjects
–> pool of attributes

Step 2: rating of stimuli
Rating of 24 stimuli on Likert scales of attributes obtained from
step 1 + assessment of given information function

Step 3: analysis of results
Principal-Component-Analysis, Generalized-Linear-Models.
Examination of correlations between acoustic properties, rated attributes,
information function.

–> Findings and results serve as a basis for further investigations!


Study Design Timbre selection
Timbre differing in parameter values („timbre dimensions“)

bright dull/dim
spectral content:

static dynamic static dynamic
temporal content:

hard soft hard soft hard soft hard soft
attack/cutoff:


Study Design Gestalt creation
Typical forms of sound-gestalt (learned associations)
descending major third of a doorbell („ding dong“) (association: welcome)
wailing siren, in germany a fourth: a-d a-d (police or ambulance)
(association: emergency - alert)

Scherer/Osinsky 1977
Tonality: major mode: indicative of pleasantness and happiness
minor mode: disgust and anger

Rhythm: rhythmic: more active, fearful, surprised
nonrhythmic: boredom

Activity = Fast tempo, high pitch level, many harmonics, large pitch variation,
sharp envelope, small amplitude variation


Fields of expertise/collaboration
Relevant ﬁelds of expertise:
music psychology, sound-/acoustic-communication, sounddesign,
sound-/music-computing, statistical methods
–> interdisciplinary team

We are not the only ones:
Product Sound Design Group TU Delft
Music Technology Group Barcelona
Music, Mind and Machine Group (MIT Media Lab , USA)
Music Information Retrieval Community
–> exchange of ﬁndings, knowledge + possible collaborations


What is the use??
Product Sounddesign
Audio-Branding
AUI (Auditory User Interfaces)
Music Information Retrieval MIR (music catalogues, sound-databases)
Mpeg7-Classiﬁcation
Electronic Music Distribution
„Perceptual Software-Synthesizers“
...


Sound Timbre and Information Transfer

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