The sound of trustworthiness: acoustic-based modulation of perceived voice personality

When we hear a new voice we automatically form a "first impression" of the voice owner’s personality; a single word is sufficient to yield ratings highly consistent across listeners. Past studies have shown correlations between personality ratings and acoustical parameters of voice, suggesting a potential acoustical basis for voice personality impressions, but its nature and extent remain unclear. Here we used data-driven voice computational modelling to investigate the link between acoustics and perceived trustworthiness in the single word "hello". Two prototypical voice stimuli were generated based on the acoustical features of voices rated low or high in perceived trustworthiness, respectively, as well as a continuum of stimuli inter- and extrapolated between these two prototypes. Five hundred listeners provided trustworthiness ratings on the stimuli via an online interface. We observed an extremely tight relationship between trustworthiness ratings and position along the trustworthiness continuum (r = 0.99). Not only were trustworthiness ratings higher for the high- than the low-prototypes, but the difference could be modulated quasi-linearly by reducing or exaggerating the acoustical difference between the prototypes, resulting in a strong caricaturing effect. The f0 trajectory, or intonation, appeared a parameter of particular relevance: hellos rated high in trustworthiness were characterized by a high starting f0 then a marked decrease at mid-utterance to finish on a strong rise. These results demonstrate a strong acoustical basis for voice personality impressions, opening the door to multiple potential applications

How trustworthy is your voice? The effects of voice manipulation on the perceived trustworthiness of novel speakers

A person’s voice is not only loaded with cues to age, sex and emotional state, listeners also readily form personality impressions of novel speakers. Based on research on face perception, suggesting that people rapidly and reliably evaluate faces on personality traits which can be summarized in a two-dimensional space, with one dimension emphasizing warmth/likability/trust and the other emphasizing strength/dominance, a similar model has been proposed for personality impressions from voices. The present study builds upon these findings, investigating how trustworthiness is perceived in voices and conveyed by novel speakers. For both male and female voices, morph continua were created between voices previously rated low/high on trustworthiness to examine whether the manipulation towards an averaged un-/trustworthy voice would shift perception of the voices towards un-/trustworthiness, respectively, and whether vocal caricatures of these prototypical voices would enhance the effect. Through an online rating experiment, 422 participants rated 18 voices on their trustworthiness. Akin to a ‘zero acquaintance’ scenario, the stimuli were sub-second vocal utterances of a single word and no contextual information was provided. Repeated measures ANOVAs and correlation analyses showed that, for male voices, there was a positive linear relationship between the responses and manipulations towards a trustworthiness caricature. For female voices, on the other hand, the results were inconclusive due to an error in the generation of the stimuli. The findings contribute to the empirical bases for understanding personality judgments from brief speech signals and are discussed in light of previous research, implications, potential applications, limitations and suggestions for further research

Generation of the voice trustworthiness continuum.

<p><b>a.</b> Thirty-two male voices saying “hello” are represented as points in a 2D “social voice space” with axes mapping onto their perceived Trustworthiness and Dominance, respectively (cf. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185651#pone.0185651.ref004" target="_blank">4</a>]). Coloured dots indicate voices within the bottom (blue dots) and top (red dots) 25% for Trustworthiness ratings. <b>b.</b> A Low- and a High-Trustworthiness prototype were generated by averaging via morphing the bottom and top 25% rated voices, respectively. <b>c.</b> A 9-stimulus “Trustworthiness continuum “was generated via morphing in 8 acoustically equal steps using the two prototypes in intermediate positions and extrapolating to low- and high- Trustworthiness caricatures at extreme positions.</p

The sound of trustworthiness: Acoustic-based modulation of perceived voice personality

<div><p>When we hear a new voice we automatically form a "first impression" of the voice owner's personality; a single word is sufficient to yield ratings highly consistent across listeners. Past studies have shown correlations between personality ratings and acoustical parameters of voice, suggesting a potential acoustical basis for voice personality impressions, but its nature and extent remain unclear. Here we used data-driven voice computational modelling to investigate the link between acoustics and perceived trustworthiness in the single word "hello". Two prototypical voice stimuli were generated based on the acoustical features of voices rated low or high in perceived trustworthiness, respectively, as well as a continuum of stimuli inter- and extrapolated between these two prototypes. Five hundred listeners provided trustworthiness ratings on the stimuli via an online interface. We observed an extremely tight relationship between trustworthiness ratings and position along the trustworthiness continuum (r = 0.99). Not only were trustworthiness ratings higher for the high- than the low-prototypes, but the difference could be modulated quasi-linearly by reducing or exaggerating the acoustical difference between the prototypes, resulting in a strong caricaturing effect. The f0 trajectory, or intonation, appeared a parameter of particular relevance: hellos rated high in trustworthiness were characterized by a high starting f0 then a marked decrease at mid-utterance to finish on a strong rise. These results demonstrate a strong acoustical basis for voice personality impressions, opening the door to multiple potential applications.</p></div

Intonation and perceived trustworthiness.

<p>The f0 contours of the 9 stimuli of the Trustworthiness continuum (from light blue for stimulus S1 to red for stimulus S9) are shown illustrating a marked change in intonation as perceived trustworthiness increases. While low trustworthiness stimuli have a flat or slightly rising f0 contour, high-trustworthiness stimuli are characterized by a marked f0 drop at the end of the first syllable to finish the second syllable on a markedly rising f0.</p

Acoustic-based modulation of perceived voice trustworthiness.

<p>Filled circles indicate group-average Trustworthiness rating z-scores for each of the 9 stimuli of the Trustworthiness continuum (spectrograms at bottom) from low-Trustworthiness caricature (S1) to low- Trustworthiness prototype (S3; blue rectangle), to the average of the two prototypes (S5), to the high-Trustworthiness prototype (S7; red rectangle) to the high- Trustworthiness caricature (S9). Note the quasi-linear modulation of Trustworthiness ratings along the Trustworthiness continuum. Open circles show average T-rating z-scores for the control continuum. Error bars and shaded areas indicate mean ± s.e.m.</p