One of the subtle but important factors in making an AI phone call feel natural is what happens during the brief moment when the AI is processing a response. Without filler audio, callers hear silence — which can feel awkward or make them wonder if the call has dropped. Filler audio solves this by playing a short, natural-sounding phrase while the AI formulates its reply.
These are the same kinds of sounds and phrases a human uses to fill thinking time: "Let me check on that for you," "Sure, one moment," or simply "Hmm." They are brief, unobtrusive, and make the conversation feel significantly more human.
How Filler Audio Works
When the AI assistant receives a caller's input and begins processing its response, there is a small latency window — typically under a second, but occasionally longer for complex queries. During this window, the platform can automatically play a filler phrase from your configured library. Once the AI has generated its response, the filler audio fades out and the assistant delivers its reply.
The filler phrases are played randomly from your library so they do not become repetitive. You can configure how many different phrases are in the rotation and how frequently they trigger — for example, you might set filler audio to only play when the processing delay exceeds 800 milliseconds, so it does not interrupt fast responses.
Configuring Filler Audio
Toggle filler audio on in your assistant's configuration under the Voice & Audio section.
Select 'Text-to-Speech' to have the assistant speak filler phrases using its configured voice, or 'Custom Audio' to upload pre-recorded filler clips for a more polished sound.
Enter the phrases you want the assistant to use. Keep them short (under 5 words) and natural. Good examples: 'Let me check that,' 'One moment please,' 'Sure thing,' 'Hmm, let me see.'
Define the minimum processing delay (in milliseconds) before filler audio kicks in. A threshold of 600–800ms is a good starting point — this prevents filler from playing on fast responses.
Recommended Filler Phrases
Match Filler Phrases to Your Brand Voice
If your assistant has a formal tone, use formal fillers like "Certainly, allow me a moment." If it has a casual, friendly tone, use phrases like "Sure thing!" or "Got it, let me check." Consistency between your filler audio and your assistant's overall tone makes the conversation feel more cohesive and polished.
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