Among the numerous human-machine interaction methods, vocal communication has become very popular in the latest years. When initially brought onto the market, vocal assistants were strictly integrated on portable devices; nevertheless, nowadays it is becoming clear that they can be a useful feature for service robotics. In particular, driving a robot vocally constitutes a more inclusive mean of communication, which guarantees a faster and more straightforward way of asserting a command. Indeed, this technology is beneficial since it allows to tackle the needs of some social groups such as the elderly, visually-impaired or physically-limited people. The main purpose of this thesis work is to analyze and compare two different approaches to vocal navigation, while developing and deploying both on a robotic platform for domestic environments.