Reducing Interlaced Noise
You may receive an email stating that your audio tracks contain interlaced noise and have a noise floor higher than -60dB.
Noise Floor is a measurement of how loud your room tone is (the white noise of your recording space). If you stood perfectly still in your recording space and hit record, how much noise is being picked up by the microphone? If you’re recording and you hear the rumbling of a garbage truck, wait until it has made its rounds and start again. Trains, planes, and automobiles in the background can be distracting and hard to remove.
To meet the audio requirements of having a noise floor no higher than -60dB RMS and ensuring that each track does not contain interlaced noise using Audacity, you can follow these steps:
1. Open Audacity:
- If you haven't already, download and install Audacity from the official website (https://www.audacityteam.org/). Launch Audacity once it's installed.
2. Import Your Audio File:
- Click on "File" in the top menu and select "Open" to import the audio file you want to edit.
3. Check Noise Floor and Remove Interlaced Noise:
a. Noise Floor:
- To measure and reduce the noise floor, select a portion of the audio that represents the background noise (no speech or music).
- Go to the "Effect" menu and select "Noise Reduction."
b. Remove Interlaced Noise:
- To address interlaced noise, you'll typically apply noise reduction and filtering techniques. Start with noise reduction:
- In the "Noise Reduction" dialog box:
- Click the "Get Noise Profile" button. This will analyze the selected portion of audio to identify the noise characteristics.
- Click "OK" to close the dialog box.
- In the "Noise Reduction" dialog box:
4. Apply Noise Reduction Effect:
- Now, select the entire track or the specific portions where you want to reduce noise.
- Go to the "Effect" menu again and select "Noise Reduction."
- In the "Noise Reduction" dialog box:
- Adjust the "Noise Reduction" slider to a value that effectively reduces the noise while preserving the audio quality. You may need to experiment with different settings. We typically recommend the following settings:
- Noise reduction (dB): 48
- Sensitivity: 10.00
- Frequency smoothing (bands): 2
- Click "OK" to apply the noise reduction.
- Adjust the "Noise Reduction" slider to a value that effectively reduces the noise while preserving the audio quality. You may need to experiment with different settings. We typically recommend the following settings:
5. Check Noise Floor Again:
- After applying the noise reduction effect, measure the RMS level of the audio to check if the noise floor is now below -60dB RMS.
- Select a portion of the audio that represents the new noise reduced background (no speech or music).
- Go to the "Analyze" menu and select "Measure RMS."
- Ensure the RMS is lower than -60dB.
6. Export Your Edited Audio:
- Once you're satisfied with the noise reduction and ensuring that the noise floor meets the requirement, you can export the edited audio by clicking "File" > "Export" and choose the appropriate export settings.
7. Listen for Artifacts:
- After applying noise reduction, listen carefully to the audio to ensure that it doesn't introduce any unwanted artifacts or affect the quality of the original audio. If you hear artifacts, you may need to adjust the noise reduction settings or consider using other noise reduction and audio restoration techniques.
It's important to note that while noise reduction can significantly improve audio quality, it should be used judiciously to avoid over-processing, which can result in unnatural-sounding audio. Experiment with the settings to strike the right balance between noise reduction and preserving the original audio quality.