“Speech Melody and Speech Content Didn’t Fit Together”—Differences in Speech Behavior for Device Directed and Human Directed Interactions

Prosodic Differences in Human- and Alexa-Directed Speech, but Similar Local Intelligibility Adjustments

“…misrecognition in computer-DS (Vertanen, 2006), as well as higher mean f0 and a larger f0 range in Lombard speech (Brumm and Zollinger, 2011;Marcoux and Ernestus, 2019). Furthermore, in contrast to other work reporting greater intensity in Alexa-DS (Raveh et al, 2019;Siegert and Krüger, 2021), we did not see a difference in intensity in the present study. This might reflect the controlled interaction, where participants were recorded with a head-mounted microphone (such that it was equidistant from their mouths for the entire experiment) and heard amplitude normalized stimuli over headphones.…”

“…Overall, we found prosodic differences across Alexa-and human-DS, consistent with routinized interaction accounts that propose people have a "routinized" way of engaging with technology (Gambino et al, 2020), and in line with prior studies finding differences in computer and voice-AI speech registers (e.g., Burnham et al, 2010;Huang et al, 2019;Siegert and Krüger, 2021). In the present study, speakers showed a systematic Alexa-DS speech style: when talking to Alexa, speakers produced sentences with a slower rate, higher mean f0, and higher f0 variation, relative to human-DS.…”

“…While here the findings align with those for another Germanic language (e.g., German in Raveh et al, 2019;Siegert and Krüger, 2021), the extent to which the same effects might be observed with other languages and other cultures is another open question for future work. For example, cultures might vary in terms of acceptance of voice-AI technology, such as due to privacy concerns (e.g., GDPR in Europe: Voss, 2016;Loideain and Adams, 2020).…”

“…For instance, the Voice Assistant Conversation Corpus (VACC) had participants complete the same type of communicative task (setting an appointment on a calendar and doing a quiz) with an Alexa Echo and a real human confederate (Siegert et al, 2018). Several studies measuring the acousticphonetic features of human-and Alexa-DS in the corpus found productions toward Alexa were louder (Raveh et al, 2019;Siegert and Krüger, 2021), higher in fundamental frequency (f0, perceived pitch) (Raveh et al, 2019), and contained different vowel formant characteristics 1 (Siegert and Krüger, 2021). Yet, similar to studies of individuals using Alexa in their homes (e.g., Huang et al, 2019), differences observed in the VACC might also be driven by physical distance from the device and conversational variations.…”

Speech Rate Adjustments in Conversations With an Amazon Alexa Socialbot

“…One possibility that the advanced speech capabilities in Alexa socialbots (in terms of speech recognition, language understanding and generation) might lead to more naturalistic interactions, whereby users talk to the system more as they would an adult human interlocutor. Alternatively, there is work showing that listeners rate 'robotic' text-to-speech (TTS) voices as less communicatively competent than more human-like voices (Cowan et al, 2015) and that listeners perceive prosodic peculiarities in the Alexa voice, describing it as being 'monotonous' and 'robotic' (Siegert and Krüger, 2020). Accordingly, an alternative prediction is that speakers will use a slower speaking rate when talking to the Alexa socialbot, since robotic voices are perceived as being less communicatively competent.…”