In a real world situation, if you push a speaker beyond its capabilities, sometimes referred to as overload, then the audio from it is clipped. This happens because there is a limit to the amount of power supplying the amplifier inside the speaker. If the requirements go beyond this, then the amplifier clips the input signal. When this happens, instead of a smooth sine wave being produced for normal audio, a square clipped waveform is output by the amplifier resulting in sound distortion.
Similarly, in digital audio, there is also a limit on how far an input sound can be represented. If the amplitude of a signal goes beyond a digital system’s limits, then the rest of it is discarded. This is particularly bad in digital audio, as a large amount of definition can be lost through audio clipping.
Effects of Clipping
Clipping can be hard, soft or limiting. Hard clipping delivers the most loudness but also the most distortion and loss of bass. Soft (also called analog) clipping delivers a smoother sound with some distortion. Limited clipping distorts the least, but it reduces the loudness the most, resulting in a loss of punch.
Prevention is always better than cure, so it is advisable to record digital audio by keeping the input signal within limits. However, if you already have digital audio files that you need to improve, you can use certain audio tools to attempt to eliminate clipping as much as possible.
Examples of audio software that can do this include:
- Software media players with normalization. Some jukebox software players such as iTunes and Windows Media Player have built-in normalization features to process audio files that can prevent songs from being clipped.
- Standalone normalization tools are third-party audio tools like MP3Gain, which can be used to normalize the tracks in your music library. They not only adjusts the loudness of songs so they all play at the same volume, but they also reduce audio clipping.
- Audio editors are programs that provide many ways to digitally process an audio file. Audio editors such as Audacity have advanced algorithms to permanently remove clipping.
- ReplayGain is similar to software tools like MP3Gain. The feature is built into some MP3 players. ReplayGain metadata can be useful for preventing very loud songs from being clipped by the hardware’s internal digital to an analog amplifier.
- CD/DVD-burning software. Disc-burning programs often come with an option to normalize tracks, especially when creating audio CDs suitable for playing on standard home entertainment equipment.