Making Machine Speech Sound Human
Bringing natural conversation quirks to AI-generated speech.
Syed Zohaib Hassan, Pierre Lison, Pål Halvorsen
― 5 min read
Table of Contents
In the world of chatting and conversation, people often stumble over their words, say "um," or repeat themselves. These little bumps in speech, known as Disfluencies, are just part of being human. However, when computers, particularly Language Models, try to talk like us, they usually skip these hiccups. This makes their speech sound less natural, which isn't great if you want a robot to seem like a real person.
This article looks at a way to make computer-generated speech sound more like actual human conversation. It deals with how adding those little speech mistakes can help make a conversation feel more real.
Why Disfluencies Matter
Disfluencies are more than just funny little quirks in speech. They help fill gaps while a speaker thinks or plans what to say next. You know, those times when you're trying to figure out how to explain something and your words get jumbled. Some common examples include stuttering or using fillers like "uh" or "like."
In casual Conversations, these pauses can make the exchange feel more relaxed and spontaneous. Studies show that when we hear these kinds of fillers, we often think the conversation is more genuine. So, if a robot can learn to include these disfluencies, it might sound more like a human and less like a robot reciting a script.
A Clever Solution
To tackle this problem, researchers have come up with a clever solution. They decided to fine-tune a large language model, which is essentially a computer program that understands and produces text. This fine-tuning process involves teaching the model how to add various types of disfluencies into its generated speech.
The method includes two main steps. First, they train the language model with a special technique to make it good at tossing in these speech errors. Then, they use Text-to-speech technology to turn the written text (with added disfluencies) back into audio form. This way, the speech sounds more natural and human-like.
Testing the Waters
To find out how well this works, a team of researchers set up a user study. They wanted to see how people reacted to speech that included disfluencies versus speech that was perfectly fluent. In simple terms, they wanted to know if adding some "ums" and "likes" made the speech sound more real or less clear.
They played participants a series of audio clips of conversations. Some clips were disfluent, meaning they included those little mistakes, while others were as smooth as butter. After listening, participants had to rate each clip based on Clarity and how natural it sounded.
The Results
The findings were pretty interesting! Participants found that conversations with disfluencies scored higher on the "natural" scale, meaning they felt more like real-life chats. However, there was a slight trade-off: the same clips were rated as a bit harder to understand. So, while we might get a more realistic vibe from a conversation with a few "uhs" thrown in, it could make things a tad confusing.
Where to Use It
The ability to make machine-generated speech sound more natural has many real-world applications. For example, this technology can be used in avatars or virtual characters designed to help train individuals in handling sensitive conversations. Imagine a chatbot helping someone practice delivering bad news. It would be beneficial if that chatbot sounded realistic, including all those natural disfluency patterns.
Such models could also be valuable in areas like gaming and education, where engaging conversations can enhance the experience.
Challenges Faced
Even though this method sounds promising, it isn’t without its challenges. One major concern is that while adding disfluencies can make speech sound more human-like, it also runs the risk of confusing listeners. If the speech is too full of "ums," it could come off as unclear or annoying.
Also, while choosing a voice model to speak this text, researchers faced difficulties. The technology can sometimes make strange sounds or pauses, which can take away from the overall experience. So they had to pick and choose the best model to ensure clear and good-sounding speech.
Ethical Considerations
As with many modern technologies, there are ethical concerns that come with using these kinds of language models. If a computer can sound more human-like, it may create situations where people might be confused about whether they are chatting with a machine or a real person. This could lead to trust issues, especially if users are unaware that they're interacting with an automated system.
Moreover, there is the risk that the machine might unintentionally amplify biases found in its training data. In real conversations, the way people express themselves varies widely, and AI might mimic only certain patterns of disfluencies, maybe linking them to specific groups of people.
To help protect against these risks, transparency is key. Anyone using this technology should make it clear when people are not talking to a real person but an AI. This helps keep trust between humans and machines intact.
Looking Ahead
The ongoing research about how to make computer-generated speech better will definitely keep evolving. The way we perceive spontaneous speech is subjective, and individual interactions can vary, creating a rich field for further exploration. Many applications could benefit from fine-tuning disfluencies to match specific contexts-like simulating stress or high-pressure situations in training scenarios.
The aim is to balance realism and understanding, ensuring that the speech remains engaging while still being clear. This technology can lead to exciting advancements in areas like gaming, education, virtual reality, and more.
Conclusion
In the world of speech and conversation, disfluencies are just a part of how people communicate. By teaching machines to include these little quirks, we can create more believable and engaging interactions. While there are challenges ahead, the potential for this technology to enhance communication is vast. The days of overly smooth and robotic chatter are numbered, as we embrace a more human-like approach to talking with our digital counterparts.
Title: Enhancing Naturalness in LLM-Generated Utterances through Disfluency Insertion
Abstract: Disfluencies are a natural feature of spontaneous human speech but are typically absent from the outputs of Large Language Models (LLMs). This absence can diminish the perceived naturalness of synthesized speech, which is an important criteria when building conversational agents that aim to mimick human behaviours. We show how the insertion of disfluencies can alleviate this shortcoming. The proposed approach involves (1) fine-tuning an LLM with Low-Rank Adaptation (LoRA) to incorporate various types of disfluencies into LLM-generated utterances and (2) synthesizing those utterances using a text-to-speech model that supports the generation of speech phenomena such as disfluencies. We evaluated the quality of the generated speech across two metrics: intelligibility and perceived spontaneity. We demonstrate through a user study that the insertion of disfluencies significantly increase the perceived spontaneity of the generated speech. This increase came, however, along with a slight reduction in intelligibility.
Authors: Syed Zohaib Hassan, Pierre Lison, Pål Halvorsen
Last Update: Dec 17, 2024
Language: English
Source URL: https://arxiv.org/abs/2412.12710
Source PDF: https://arxiv.org/pdf/2412.12710
Licence: https://creativecommons.org/licenses/by-nc-sa/4.0/
Changes: This summary was created with assistance from AI and may have inaccuracies. For accurate information, please refer to the original source documents linked here.
Thank you to arxiv for use of its open access interoperability.