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In-Depth Information
4.3.1.2 Modelling the Perceptual Effects
In the case of sound synthesis based on the modelling of perceptual effects, the
sound generation is not merely based on the simulation of the physical or signal
phenomena. This approach enables the synthesis of any kind of sounds, but it
necessitates the understanding of the perceptual relevance of the sound attributes
that characterize the sound category in question. Concerning environmental sounds,
several studies have dealt with the identi
cation and classi
cation of such sounds
(Ballas
1993
; Gygi and Sha
ro
2007
; Gygi et al.
2007
; Vanderveer
1979
).
A hierarchical taxonomy of everyday sounds was proposed by Gaver (
1993b
) and is
based on three main categories: sounds produced by vibrating solids (impacts,
deformation, etc.), aerodynamic sounds (wind,
fire, etc.) and liquid sounds (drops,
splashes, etc.). This classi
cation related with the physics of sound events and has
shown to be perceptually relevant. Hence, the perceptual relevance of these cate-
gories encourages the search for invariant sound morphologies speci
c to each
category. This notion is developed in the next section.
4.3.2 Invariant Sound Morphologies
The invariant sound morphologies associated with the evocation of sound attributes
can either be linked to the physical behaviour of the source (Giordano and
McAdams
2006
), to the signal parameters (Kronland-Martinet et al.
1997
)orto
timbre qualities based on perceptual considerations (McAdams
1999
). This means
that different synthesis approaches can be closely related, since in some cases,
physical considerations and in other cases, signal variations might reveal important
properties to identify the perceived effects of the generated sounds. In particular for
environmental sounds, several links between the physical characteristics of actions
(impact, bouncing, etc.), objects (material, shape, size, cavity, etc.) and their per-
ceptual correlates were established in previous studies (see Aramaki et al.
2009
;
Aramaki et al.
2011
for a review). In summary, the question of sound event rec-
ognition was subject to several inquiries (e.g. Warren and Verbrugge
1984
; Gaver
1993a
,
b
) inspired by Gibson
s ecological approach (Gibson
1986
) and latter for-
malized by McAdams and Bigand (
1993
). This led to the led
'
nition of structural and
transformational invariants linked to the recognition of the object
'
s properties and
its interaction with the environment, respectively.
Sounds from impacted objects
: Impact sounds have been largely investigated
in the literature from both physical and perceptual points of view. Several studies
revealed relationships between perceptual attributes of sound sources and acoustic
characteristics of the produced sound. For instance, the attack time has been related
to the perception of the hardness of the mallet that was used to impact the resonant
object, while the distribution of the spectral components (described by inharmo-
nicity or roughness) of the produced sound has been related to the perceived shape
of the object. The perceived size of the object is mainly based on the pitch. A
physical explanation can be found in the fact that large objects vibrate at lower
eigenfrequencies than small ones. Finally, the perception of material seems to be
