This will highlight the entire audio file, indicating that the noise reduction will be applied to the entire file.

Next, select the entire audio file by going to the “Edit” menu and choosing “Select” > “All”. In the Noise Reduction window, click on the “Get Noise Profile” button and it will analyze the selected audio and create a noise profile based on the characteristics of the background noise. This will open the Noise Reduction window. Once you have selected the portion of the audio with background noise, go to the “Effect” menu and select “Noise Removal”.

Make sure to select a portion that is long enough to get a good representation of the background noise (around 10 seconds should be sufficient). To do this, use your mouse to click and drag over a section of the audio waveform that represents the background noise. To remove background noise from your audio, you need to first select a portion of the audio that contains only the background noise. Step 3: Select a portion of the audio with background noise

Removing background noise in audacity