Playback degrades in quality over time

My four year old daughter is a big fan of audiobooks and for a bit of fun I’ve been trying to record one of her favourite books for her.

I’m using a Sennheiser PC 8 Skype headset with a USB connector onto my Mac 10.5.8 which has Audacity on it.

Initially the playback sounds good but after about 15s some clicks start to appear and over time the static and crackling builds up and up until the recording sounds terrible. However the sound at the beginning is perfect for my purposes. I’m not after studio quality and it’s doubly annoying because the audio starts out fine and then degrades.

I’ve already set up the microphone as an aggregate device using Audio MIDI setup and that cleared up some initial quality problems. A friend suggested it might be noise cancellation in the headset creating some kind of feedback. Any ideas?

A few Macs seem to have some playback issues with recent Audacity, so to be sure whether the recording is the problem or not, please export the recording as WAV and play it in iTunes or QuickTime. Does it crackle there?


Thanks for the reply. Unfortunately it crackles just as much when I play it on other programmes. I tried iTunes and VLC player.

Then it seems to be a recording problem not an Audacity problem.

Why do you need to set the headset up as an aggregate device? Are you recording from two headsets at once?

Look in Audacity’s Transport Menu for Software Playthrough and click to turn it off if it’s checked (ticked).

Current Audacity is at v 2.0.5 and has an audio I/0 update so you may as well upgrade: .