Denoising, or noise reduction, is a process used to remove unwanted background noise from audio recordings. While Apple devices don't have a built-in command-line tool specifically for denoising, there are several methods and applications available that can help achieve this task effectively.

Examples:

1. Using GarageBand

GarageBand is a powerful digital audio workstation (DAW) available on macOS and iOS that can be used for basic audio editing, including noise reduction.

• Step 1: Open GarageBand and create a new project.
• Step 2: Import the audio file you want to denoise by dragging it into the workspace.
• Step 3: Select the audio track, then click on the "Smart Controls" button (or press B on your keyboard).
• Step 4: In the Smart Controls panel, look for the "Noise Gate" option. Adjust the threshold slider to reduce unwanted noise. The Noise Gate will help in cutting out low-level noise that falls below a certain threshold.

2. Using Audacity

Audacity is a free, open-source audio editing software that works on macOS and is widely used for noise reduction.

• Step 1: Download and install Audacity from its official website.
• Step 2: Open Audacity and import your audio file by selecting File > Import > Audio.
• Step 3: Highlight a section of the audio that contains only the noise you want to remove.
• Step 4: Go to Effect > Noise Reduction, then click on "Get Noise Profile."
• Step 5: Select the entire audio track by pressing Cmd + A.
• Step 6: Return to Effect > Noise Reduction, adjust the noise reduction settings to your preference, and click "OK" to apply.

3. Using Logic Pro

Logic Pro is another professional-grade DAW available on macOS that provides advanced tools for denoising.

• Step 1: Open Logic Pro and create a new project.
• Step 2: Import your audio file into the project.
• Step 3: Select the audio track and open the "Channel EQ" plugin.
• Step 4: Use the EQ to identify and reduce frequencies that correspond to noise.
• Step 5: For more precise control, use the "Noise Gate" or "Expander" plugins to further reduce noise levels.

Alternatives:

If you're looking for command-line solutions, macOS does not have a native CLI tool for denoising. However, you can use third-party command-line tools like ffmpeg with noise reduction filters, though this requires additional setup and expertise.