More and more respondents are completing Web surveys on mobile devices. Some studies have found that responses to open narrative questions are affected by use of mobile devices, especially smartphones. Given the rise of voice input on smartphones in general, it is worth investigating the feasibility of voice input for answering open questions on smartphones. The goal of this research note is to study (1) the extent to which people already use voice input on their mobile devices (for ìeverydayî life), (2) the extent to which they would be willing to use voice input to answer open questions in Web surveys, and (3) the factors that may affect the willingness to use voice input. Based on data from a survey in Spain in 2016, we found that around half of our sample already uses voice input (at least sometimes) and that also around half of the sample is willing to use it to answer open narrative questions if this was possible. Several variables were found to have a significant association with the willingness to use voice input: the use of voice input in everyday life, the frequency of Internet access through a smartphone, and the perceived difficulty of answering the current survey.