# setPreferredIOBufferDuration(_:) Sets the preferred audio I/O buffer duration. ``` func setPreferredIOBufferDuration(_ duration: TimeInterval) throws ``` ## Parameters `duration` The audio I/O buffer duration, in seconds, that you want to use. ## Discussion This method requests a change to the I/O buffer duration. To determine whether the change has taken effect, use the [`ioBufferDuration`](/documentation/AVFAudio/AVAudioSession/ioBufferDuration) property. The audio I/O buffer duration is the number of seconds for a single audio input/output cycle. For example, with an I/O buffer duration of 0.005 s, on each audio I/O cycle: - You receive 0.005 s of audio if obtaining input. - You must provide 0.005 s of audio if providing output. The typical maximum I/O buffer duration is 0.093 seconds (corresponding to 4,096 sample frames at a sample rate of 44.1 kHz). The minimum I/O buffer duration is at least 0.005 seconds (256 frames) but might be lower depending on the hardware in use. You can set a preferred I/O buffer duration before or after activating the audio session. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)