Audio effects are designed to manipulate sound. They can be software (computer programs or plugins), or hardware (like guitar effects pedals or rack-mounted machines).

The effect these devices have on sound can vary from a subtle colouration to all-out sonic terrorism! There are a dizzying array of effects processors on the market which tend to fall into a number of broad categories:

• Modulation effects (e.g. Chorus, Flangers, or Phasers) gradually sweep back and forth over time, creating various characteristic sounds
• Time-based effects (e.g. Delay and Reverb) create echoes and reverberations which can do anything from simulate the sound of a room to creating mesmerizing rhythmic patterns
• Pitch effects can create harmony from thin air or fix dodgy singing (like the infamous Autotune)
• Distortion effects (e.g. Overdrive, Fuzz) increase signal volume until smooth sound waves get 'clipped' into ugly squares, creating thick harmonics and endless sustain
• Dynamic effects (e.g. Compression, Limiters) make levels consistent and can make music thick and punchy

Audio effects are used by musicians to shape their tone into distinctive new forms, and by record producers and mastering engineers to make recordings sound more rich and full. Effects used to be the preserve of professional studios and millionaire rock stars, but the relentless march of technology means even beginners can now experience and use them to their heart's desire.

Used carelessly, effects can rob an instrument of character and leave it lost in the mix... But in the hands of a master (such as U2's The Edge) a musician can become a one-man soundscape.

Ear training can give you a deeper understanding of audio effects and help you:

• Recognise common audio effects by ear
• Creatively use effects to enhance your musical tone
• Make your demos sound punchier by mastering dynamic range compression
• Hear when vocalists have been auto-tuned (even tastefully!)
• Hear the difference between natural and artificial reverb

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