Psychology
2012. Vol.3, No.8, 606-609
Published Online August 2012 in SciRes (http://www.SciRP.org/journal/psych) http://dx.doi.org/10.4236/psych.2012.38091
606
Emotional Reactions to Sounds without Meaning
Daniel Västfjäll
Department of Behavioural Science and Learning, Linköping University, Linköping, Sweden
Received May 19th, 2012; revised June 18th, 2012; accepted July 16th, 2012
The present research examined the relationship between emotional reactions to sounds without meaning
(tone and noise complexes) and objective sound descriptors. Two experiments showed that the core affect
dimensions valence and activation were related to perceived loudness (intensity) and sharpness (perceived
high frequency content), respectively. These results can be used as design criteria for emotion induction
with sounds, implementation of emotional sounds in products, as well as in research on environmental
noise perception.
Keywords: Emotion; Sound
Introduction
Early research by Wundt suggested that emotional reactions
to auditory events could be mapped onto a pleasantness-un-
pleasantness (Lust-Unlust) dimension (Wundt, 1924). Later stud-
ies on emotional reactions to non-musical, non-vocal sounds
have almost exclusively studied positive-negative responses
(Todd, 2001; Vitz, 1973), even though Wundt himself con-
cluded that emotional reactions to auditory rhythms needed to
be described by additional dimensions (strain-relaxation and
excitement-calmness). More recent studies on the relationship
between emotional responses and sound characteristics have
focused on a single affective state annoyance. Annoyance has
been shown to correlate moderately with descriptors of physical
characteristics such as equivalent dB(A) level for community
noise, and with other psychoacoustic dimensions such as per-
ceived sharpness and roughness for specific sound sources
(Berglund & Lindvall, 1995; Berglund, Hassmén, & Preis,
2002; Zwicker & Fastl, 1999).
Other research have demonstrated that two dimensions, va-
lence and activation, are suited to describe emotional reactions
to sounds (Björk, 1985). Bradley and Lang (2000) found that
self reported emotional reactions to 60 natural sounds were
scattered in a two-dimensional space of valence (pleasantness-
unpleasantness) and activation (arousal) (but see Stevenson &
Jameson, 2008 for a discrete emotional account of these
sounds). Moreover, the reactions were clustered along two axes,
one stretching from low activation and neutral valence to un-
pleasant high activation (avoidance), and the other one from
low activation and neutral valence to pleasant high activation
(approach). Importantly, Bradley and Lang found that valence
ratings was very weakly related to sound level (r = 0.07) and
activation ratings was moderately related (r = 0.38). However,
these correlations only accounted for 14% of the variance. Af-
fective reactions to these sounds must therefore be related to
other physical sound descriptors than sound level and/or other
psychological characteristics not captured by physical descrip-
tors (Asutay & Västfjäll, 2012; Asutay et al., 2012). Bradley
and Lang used recordings of a number of everyday sounds
sources such as recordings of a dog barking, cries from an
amusement park etc., why they could conclude that the ob-
served reactions were due to other aspects of the stimuli (i.e.
affective meaning1).
The present research complements the research by Bradley
and Lang by focusing on physical sound determinants of emo-
tional reactions. Results from such research are important for
many applications including emotion induction with sounds,
assessment of subjective noise reactions, prediction of subjective
noise experience, sound design, auditory interfaces, and devel-
opment of new sound abatement approaches (Desmet, 2002;
Picard, 1997; Västfjäll et al., 2002). A slightly different ap-
proach than that of Bradley and Lang’s is therefore used in the
present research. Rather than using everyday sounds with easily
identified meaning (such as recordings of people, animals, ac-
tivities), the present research focused sounds devoid of emo-
tional meaning (noise and tone complexes) induced through
activation of episodic memories or similar mechanisms (Juslin
& Västfjäll, 2008). Even though everyday emotional reactions
are related to both sound characteristics and the appraisal of the
sound/sound source (Asutay & Västfjäll, 2012; Tajadura, Väl-
jamäe, Asutay, & Västfjäll, 2010, Tajadura, Larsson, Väljamäe,
Västfjäll, & Kleiner, 2010), it may be desirable to first establish
a relationship between sound characteristics and emotional
reactions.
The aim of the present research is therefore to study 1) if
emotional reactions to tone and noise complexes that vary in
the two-dimensional emotional experiential space; 2) to find
self-reported and physical correlates to valence and activation.
A related aim is to show that auditory dimensions other than
loudness or sound level influence emotional reactions to sounds
(Zwicker & Fastl, 1999).
1Affective meaning is defined as an evaluation of auditory events where
the object/activity creating the sound is easily identified (Ballas, 1993),
and that this activity/object is perceived as positive-negative. Furthermore
it is the object/activity, rather that the acoustic information, that creates
the affective reaction
In Experiment 1, participants either rated their emotional re-
actions to 16 tone and noise complexes or rated the perceptual
or psychoacoustic qualities of the same sounds. On basis of the
results of Experiment 1, Experiment 2 used experimentally

D. VÄSTFJÄLL
manipulated sounds to further investigate physical determinants
of valence and activation.
Experiment 1
The first experiment aimed at investigating the relationship
between emotional reactions and sound characteristics. An
exploratory approach was taken where 40 participants rated
their emotional reactions to stationary sounds. Twenty additional
participants rated the sounds in terms of their perceptual prop-
erties.
Participants. Sixty undergraduates at Chalmers University
of Technology, Göteborg, Sweden, an equal number of men
and women, participated on a voluntary basis. They were com-
pensated with the equivalence of US$10. Their mean age was
26.1 years (SD 4.1). All participants had normal hearing as
determined by an audiogram.
Measures. The affect measures consisted of two bipolar
scales each defined by three adjective pairs found in previous
research to tap valence and activation, respectively (Västfjäll et
al., 2002; Västfjäll & Gärling, 2007). Sleepy-awake, dull-peppy,
and passive-active were used to define the activation scale,
displeased-pleased, sad-glad, and depressed-happy were used to
define the valence scale. Numbers ranging from –4 over 0 to 4
were typed beneath the three adjective pairs defining a scale.
Participants were requested to circle the number that cor-
responded to their feeling.
From previous research on auditory event evaluation (Björk,
1985; von Bismark, 1974; Solomon, 1958), a set of sensory
adjectives were identified and selected. These included (trans-
lated to English) hard, strong, low, loud, clear, tonal, even, high
in frequency, low in frequency, rough, soft, regular, irregular,
weak in tone, harsh, natural, artificial, tiring, sharp, edgy, blunt,
strong in tone, presence of extraneous sounds, and balance
between left and right ear.
Stimuli and presentation. Sixteen binaural sounds varying
in psychoacoustical qualities were used. The sounds were tone
and noise complexes and a pilot rating experiment suggested
that they were not systematically identified as a having a specific
meaning. Psychoacoustic metrics were calculated for all sounds
using a HEAD Acoustics Artemis analysis system on a PC. The
sounds varied in psychoacoustical properties such as loudness
(intensity), roughness (frequency or amplitude modulations
between 20 - 70 Hz), sharpness (high frequency components),
fluctuation strength (amplitude and frequency modulations
below 20 Hz), and tonal content (tone-to-noise ratio; see
Zwicker & Fastl, 1999 for an overview of these metrics). The
sounds were presented in an acoustically well-damped room
over Alpine loudspeakers, using cross cancellation technique to
maintain binaural information.
Procedure
Emotion ratings. Participants (n = 40) arrived individually
to the laboratory. After having been seated participants listened
to the first of in all 16 sounds sequentially presented. Each
sound was presented for 2 minutes. Participants were asked to
rate their affective reactions on the adjective scales by checking
each scale to indicate the degree to which the adjective de-
scribed how they felt at the time of listening to the sound.
Following the procedure devised by Bradley and Lang
(2000), participants were instructed to refer how they felt when
listening to the sound. The moment participants were asked to
refer to when rating their affective reactions was indicated by a
“rating probe” consisting of a blinking arrow on a computer
screen. The rating probe was displayed approximately in the
middle of the duration of each sound.
After listening to a sound, participants were instructed relax
and try to return to a neutral affective state. When participants
felt relaxed, they were instructed to rate how they felt on the
two adjective scales. After this they continued with the next
sound by clicking a button on the computer.
Sensory ratings. 20 separate participants rated the sensory
characteristics of the sounds. The procedure was similar to the
affective ratings condition. Sounds were presented in different
random orders for each participant. One minute was allowed
between each sound. Participants could indicate any number
from 0 (not at all) to 8 (very much) for each of the adjectives.
The procedure took in total approximately one hour.
For each participant a different random order of the sounds
was generated. The participants needed about sixty minutes to
complete the ratings. After listening to the sixteen sounds, par-
ticipants were debriefed, compensated and thanked for their
participation.
Results and Discussion
First, emotional reactions were examined. Valence and acti-
vation were relatively independent (r = 0.09, p > 0.05). Figure
1 shows that the sounds induced variations in emotional
reactions in terms of activation and valence. This was sub-
stantiated by a within-subject ANOVA on activation, F(2.12,
49.66) = 12.44, p < 0.001, and on valence, F(2.77, 46.82) =
20.10, p < 0.001.
To assess the relationship between the psychoacoustic met-
rics and emotional reactions multiple regression analyses with
either the mean valence or mean activation index as dependent
variable was performed. The analysis for the activation index
showed that sharpness contributed significantly (β = 0.68, p <
0.01) for an R2adj of 0.42, F(2, 14) = 11.98, p < 0.01.
Figure 1.
Emotional reactions to 16 tone and noise complexes along
the valence and activation dimensions (Experiment 1).

D. VÄSTFJÄLL
For the regression analysis of the valence index the loudness
(β = –0.89, p < 0.001) and roughness (β = 0.38, p < 0.05) met-
rics contributed significantly giving an R2adj of 0.81, F(3, 13) =
33.42, p < 0.01.
To further corroborate these results, sensory ratings from the
separate sample were investigated. A PCA was first performed
on the correlations between the mean ratings over individuals
for each sound to determine the underlying perceptual dimen-
sions. The PCA resulted in five factors with eigenvalues larger
than 1.0, that together accounted for 76% of the variance. Ad-
jectives denoting loudness loaded on the first factor, adjectives
describing mainly sensory sharpness loaded on the second fac-
tor, adjectives describing fluctuation and modulation loaded on
the third factor, adjectives describing tonal content loaded on
the fourth factor, and finally adjectives concerning the natural-
ness vs. artificiality of the sounds loaded on the fifth factor.
From the PCA five indices of loudness, sharpness, fluctuation
strength, tonal content, and naturalness were formed by sum-
ming with the appropriate sign.
Next, multiple regression analyses were performed with each
of the affect indices as dependent variables. Sharpness (β =
0.47, p < 0.05) and tonal content (β = –0.43, p < 0.05) indices
were reliably related to the activation index, R2adj = 0.53, F(3,
13) = 12.85, p < 0.01, indicating that activation increases with
increasing sharpness and decreases with increasing tonal con-
tent. Loudness (β = –0.51, p < 0.01) and naturalness (β = 0.32,
p < 0.05) were reliably related to valence, R2adj = 0.66, F(3, 13)
= 18.83, p < 0.01.
The results of the first experiment showed that tone and noise
complexes varied in both valence and activation. More impor-
tantly, the results suggested that valence and activation reac-
tions differed in their determinants. Activation was related to
rated or perceived tonal content and sharpness, whereas valence
was associated with perceived loudness, roughness, and natu-
ralness.
To further study these relationships, Experiment 2 employed
experimentally manipulated sounds.
Experiment 2
Method
Participants. 16 undergraduates, 7 female and 9 males, vol-
untarily participated in the experiment. Their mean age was
22.3 (SD, 2.12). All reported having normal hearing.
Measures. The affect rating scales from Experiment 1 was
used.
Stimuli and Presentation
Activation manipulation. Since the first experiment showed
that activation was related to perceived sharpness of the sound a
set of five sounds varying from strong low-frequency tonal
content strong to high frequency content was created using
signal processing. A tone-noise complex was used as the base
stimulus (reference sound). From this sound a number of modi-
fied versions were created where the fundamental frequency
and/or harmonics or the noise spectrum were changed. The
modifications for strong tonal low frequency content were an
amplification of the fundamental frequency (100 Hz) of 6 and
12 dB, respectively. To increase the high frequency content of
the sound, a high-pass filter was used to amplify noise and
tones above 3000 Hz with 6 and 12 db, respectively. Finally, all
sounds were equalized to the same loudness level and were
replayed to participants at 60 dBA2.
Valence manipulation. For the valence manipulation only
loudness was changed. The same reference sound that was used
for the activation manipulation was again used, but replayed at
five different sound levels (40, 50, 60, 70, and 80 dBA).
All stimuli were generated using digital signal processing
software and were digitally stored on a computer. Stimulus
presentation was made on computers using an experiment pro-
gram. The sounds were delivered via Stax electrostatic head-
phones.
Procedure. Participants performed the experiment individu-
ally or in groups of maximum three persons at a time. Upon
arrival to the laboratory, participants were first instructed how
to use the scales and equipment. They were instructed that they
would perform ratings of their reactions to various sounds.
Participants then listened to and rated five trial sounds (other
than the test stimuli). After that they rated the five trial sounds,
participants continued with remaining two sound blocks. The
blocks and order within blocks were counterbalanced across
participants. When participants had rated all the sounds, they
were debriefed, compensated, and thanked for their participation.
Results and Discussion
Activation manipulation. The within-subjects ANOVAs for
activation, F(2.31, 34.66) = 46.01, p < 0.001, was as expected
significant. As may be seen in Figure 2, activation increases
with increasing sharpness. The ANOVA for valence was not
significant F(1.44, 21.66) = 1.09, p > 0.05.
Valence manipulation. The within-subjects ANOVA for
valence was significant, F(2.86, 42.96) = 24.12, p < 0.001
(Figure 3). The ANOVA for activation was also significant,
F(1.99, 37.97) = 4.01, p < 0.05. A contrast however showed
that only the 80 dBA vs 40 dBA was significantly different.
In line with experiment 1 and previous findings (Västfjäll et
al., 2002), Experiment 2 yielded support for the idea that va-
lence reactions are mainly affected by loudness and the activa-
tion dimension by perceived sharpness of the sound.
Figure 2.
2A pilot experiment indicated that the perceived sharpness/tonal con-
tent varied as predicted, whereas perceived loudness remained con-
stant.
Valence and activation ratings for sharpness modifications (Experiment
2).
608

D. VÄSTFJÄLL
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