Noise Floor

The noise floor is the level of background noise present in an audio recording when no intentional sound is being produced. It is measured in decibels (dB) and represents the baseline level of unwanted sound in the recording, including electronic hiss, room ambience, equipment noise, and any other non-speech audio.

Audiobook distribution platforms set strict noise floor requirements. ACX requires a noise floor below -60 dB, meaning the background noise must be at least 60 decibels quieter than the reference level. This ensures listeners hear clean speech without distracting background hiss or hum.

In traditional audiobook production, achieving a low noise floor requires a properly treated recording space (soundproofing, acoustic treatment), high-quality microphones and preamps, and careful gain staging throughout the signal chain. Even professional studios sometimes struggle with noise from HVAC systems, external traffic, or electrical interference.

AI-generated audiobook audio has a significant advantage in noise floor performance. Because TTS engines generate audio digitally rather than capturing it through microphones in a physical space, the output is inherently clean. The noise floor of AI-generated speech is typically well below -60 dB, often approaching -90 dB or lower. This eliminates the need for noise reduction processing that can degrade audio quality.