A muffled sound is an unclear or quieter sound signal that exists in your recording. Note that these sounds are intended to be prominent and audible in the end product. This sound is gotten due to a number of factors. Some of these factors are recording with the mic placed far away or too close to the sound signal or using the wrong equipment. Picking the wrong equipment can range from using the wrong choice of a microphone or using the wrong power supply equipment. In some instances, you will have an eccentric sound that sounds like someone speaking through a pillow, or the audio sounds like someone speaking underwater. Such a recording is usually hard to listen to as some words are not clearly audible.
Import the audio file into audacity using Ctrl + Shift + I. Note that the file being imported has a modulation of intonation or varying pitch in the voice. Once the file is imported double click on the waveform to select it. Copy the waveform.
Next, click on Tracks on the menu tab followed by hovering your mouse pointer over Add New. From this new drop-down list click on Stereo Track. Now paste the file in this new track.
Make sure that the waveform below is selected as is in the image above. Next, click on the effects option in the menu tab. From the dropdown list that appears click on the Paulstretch option.
This will open this pop-up box.
The Paulstretch effect is used in slowing down audio by extreme amounts without having any changes made to the pitch. In this box, there are two entries: The Stretch Factor and Time Resolution (seconds).
The Stretch Factor entry allows you to input how much longer the stretched sound will be in comparison to the original sound. If you input 10 for a minute long audio it will stretch it into 10 minutes of audio. Ideally, you can set it as two.
Type in 0.5 in the Time Resolution entry. Whatever is keyed in should be smaller than the selection made in the waveform.
You can click on the preview to sample how the effect is being applied to the file. Once you have ascertained that everything sounds ok click on OK to apply the effect to the file.
A progress bar will appear and the time it takes for this to be applied to completion will depend on the length of the file. The longer audio file will take longer.
Once done you will notice that the length of the wave file increases and it will be longer than the waveform above. After Paulstretching, you will need to change the speed of the audio file. Click on Effects in the menu tab followed by the Change Speed option in the drop-down list that comes up.
In the pop-up box that comes up, set the percent change as 100, and in the Speed Multiplier entry type as 2.
Click Ok to finalize.
The two files ought to be of the same length.
Lastly, you will use the High Pitch Filter effect. The High Pitch Filter is found under the Effect option in the menu tab.
In the pop-up box, there is two entries Frequency (Hz) and Roll-off (dB per Octave).
The Frequency should be set based on the frequency range that you got from the Plot Spectrum Frequency Analysis. A point to note
Press OK to finalize.
Muffled vocals can be caused by a number of issues. It can be a by-product of using noise reduction effects among other causes. Before going to the effects, check your frequency analysis spectrum.
Click on Analyze in the menu tab followed by Plot Spectrum Option.
Once you do this a pop-up box with a graph will appear.
On the bottom axis, the frequency for my audio gets to about 11,000Hz. The human hearing range is between 20 to 20,000 Hz meaning I can make a little adjustment. This figure gives us a reference point for the next step.
This next step is reducing the low-frequency noise using the High Pass Filter. This filter is used to pass the frequencies that are above the cutoff frequency set. At the same time, it attenuates frequencies that are below its cutoff frequency.
To do this first double-click on the waveform to select it. Head over to the Effects option in the menu tab. Click on the High Pass Filter option.
This pop-up box will appear.
The figure that you input in the Frequency (Hz) entry will make sure that sounds below it is attenuated whenever the sound level drops below the figure put in. Therefore it kills off those low sounds but not entirely and at the same time makes the louder signal better.
Fixing muffled vocals can sometimes be strenuous and unsuccessful.
As an audio editor and an audio producer, the most important thing not to compromise on is the audio quality. To make sure the quality of the audio is perfect we check for issues like background noise, and quality of the audio which includes issues with muffled audio.
This article looks at dealing with it as an already existing issue. On the other hand, what can you do to prevent it? Next time before recording make sure you pay attention to these:
- Make sure the microphone placement is alright. It should not be far off nor too close to the sound signal.
- Ensure the environment that you are recording in does not have background noises which will prompt you to use noise removal effects which will eventually bring about the muffled effect on your audio file.
- Ensure that you are using the right equipment. Emphasis on the choice of microphone and power equipment.