How to Make AI Voice Sound Less Robotic

The creation of AI voices, courtesy of Text to Speech (TTS) technology, has been a game changer in the field of media and content creation. The Sauder School of Business found that content creators on TikTok are nearly 24% more productive per week than those who don't use AI voices for their videos.

The uses of TTS technology don't end there!

All your favorite voice assistants, including Apple's SIRI, Amazon's Alexa, and Google Assistant, run on this technology.

That said, one recurring issue with using AI voices right out of the box is that they most likely sound more robotic than natural, which can detract from their ability to connect with audiences. This lack of human-like nuances can make them feel impersonal, limiting their potential, especially in content that needs to evoke emotions.

However, there are a few tricks and techniques that you can apply to these AI voices to make them sound more natural and humanlike, and this blog will focus on them. So, let's dive in!

Techniques to Make AI Voices Sound More Natural

There are essentially three primary techniques you can apply to refine a typical robotic AI voice and make it sound more natural. They are as follows:

1. Voice Modulation

Voice modulation is the simplest method for making your AI voice sound natural. By definition, it is the process of altering the pitch, tone, and speed of one's voice when communicating.

Think of Sir David Attenborough or Morgan Freeman's narrations in documentaries or speeches of great orators like Winston Churchill and Martin Luther King, Jr. They all use voice modulation to emphasize specific words, alter tone for effect, and control their speech's pace to engage their audience effectively.

The same principles can be applied to voices created via Artificial Intelligence (AI) to make them sound more natural. You can edit your TTS-generated audio files using tools such as Adobe's Audition or Audacity to adjust these parameters with a few simple steps.

These tools can also help you get rid of any unwanted noise, and add sound effects or background noise to further improve the quality of your voiceovers.

2. Emotion Infusion

Our ability to feel and convey emotions significantly differentiates us from a voice created by even the most advanced combinations of Machine Learning (ML) and AI.

The same can be done to robotic AI voices via a process called Emotion Infusion, which involves adding emotional intonations to AI-generated phrases and sentences to mimic natural speech.

Adding emotional intonations to AI voices helps express empathy, enthusiasm, or reassurance. By mimicking human speech patterns, emotion infusion makes the voices more relatable and natural. It also adds warmth and personality, allowing users to connect on an emotional level.

A great example is a TTS tool like Murf AI, which enables you to infuse specific emotions (like excitement, sadness, and empathy, to name a few) into its TTS recordings.

For instance, if you’re creating an advertisement, you can use Murf AI to infuse excitement into promotional messages by raising the pitch and increasing the tempo to match the enthusiasm of a limited-time offer.

3. Prosody Adjustment

The final technique you can use to create natural-sounding voices using AI is to employ Prosody Adjustment. Prosody, in linguistics, refers to the rhythm, stress, and intonation of natural speech.

Adjusting these parameters with voice editing software will help you control how a robotic AI-generated voice emphasizes specific words, alters pauses, modulates sentences, and converts them into something that sounds natural.

You can again use a tool like Murf AI, upload your audio files and use its capabilities to adjust the prosody of the AI voices to align more with the natural cadence of speech.

For example, if you are creating an audio file for a guided meditation, you can adjust the prosody to include deliberate pauses between instructions and apply gentle emphasis to words like "breathe" or "calm" to form a soothing and natural cadence that meditation requires. 

Techniques for AI Voice to Be One Step Ahead

If you have implemented all of the above techniques, your AI voices should no longer sound robotic. However, there are still a few additional simple steps you can take to make them nearly indistinguishable from human-like speech.

1. Speech Rate Adjustment

We humans tend to vary our speaking speed depending on the situation subconsciously. But AI-generated voices remain monotonous, which makes them sound robotic. Therefore, varying the speed of an AI voice slightly can help you achieve a more natural flow, similar to how we do based on the conversation or context.

However, the key is not to overdo it. Extreme variations can sound unnatural or even awkward, so finding the right balance for each phrase is crucial.

For example, in an eLearning module for corporate training, the delivery needs to be professional and clear. Overly dramatic shifts in pitch and tempo will make the delivery seem theatrical or even distracting, which does not serve the purpose here.

2. Pitch Variation

Altering pitch is another effective way to move away from monotonous, robotic voices. Take a moment to analyze how humans speak. We alter our pitch to convey various emotions. When we are excited, our pitch goes higher, and when the conversation gets serious, our pitch lowers.

Slight alterations in the pitch can also mean the difference between asking a question and making a statement. Thus, adding slight pitch variations to your AI voices with Murf can elevate and add a level of depth to the character you want them to portray.

Training your TTS Models for Humanlike Voices

The key to generating natural sounding voices is to train your AI model with a diverse range of voice samples. Diverse in this context can include geographical, demographic, and emotional diversity.

You can further improve your sample set by adding voice samples with manually altered voice parameters like pitch, tone, and speed and expressing different emotions and vocals with imperfections like background noise or varying levels of clarity.

If there are any ML experts among you, use pre-trained speech models to get a head start and incorporate regularization techniques to overcome problems like overfitting and generalization.

Summing It Up

Simply put, it is not impossible nor difficult to convert a robotic AI voice into one that sounds natural. With a little practice and the right tools, you should be able to apply these techniques to elevate your AI-generated voices to create a more natural and engaging listening experience for your audience.