Stereo

Stereo Sound

  • Stereo sound is a method of sound reproduction that creates an illusion of directionality and audible perspective.
  • It involves the use of two or more independent audio channels typically received through two speakers positioned apart from each other.
  • The main types of stereo are: true stereo (two or more microphones capturing sound across the soundstage) and panned stereo (monophonic recordings panned to specific locations in the stereo field during mixdown).

Stereo Recording Techniques

  • Different stereo recording techniques allow for varied stereo width and depth, creating a more immersive sound experience.
  • Commonly used techniques include XY, ORTF, NOS, AB, MS (Mid-Side), and Blumlein Pair.
  • XY positioning uses two cardioid microphones at an angle to create a strong centre image and good mono compatibility.
  • ORTF positioning uses two microphones at a wider angle and distance apart to capture a more natural stereo image.
  • Mid-Side technique offers the advantage of variable stereo width in post-production.

Stereo Mixing

  • In stereo mixing, placement of sounds in the stereo field is achieved through panning.
  • With panning, elements in the mix are moved between the left and right speakers to create a stereo image.
  • It’s important to maintain a balance; if a sound is panned hard right, balancing elements should be panned left.

Phase Issues

  • When combining or positioning signals in the stereo field, phase issues can occur, causing a ‘hollow’ or ‘thin’ sound.
  • Use of phase correlation meter or vectorscope can help visualise and correct such issues.

Mono Compatibility

  • Mono compatibility is important as many listeners will hear music in mono—either through a single speaker (like a smartphone) or as background music in public spaces.
  • Simulated mono (checking mono compatibility) lets you test how your stereo mix will sound in mono.
  • Over-reliance on stereo effects can cause issues when summed to mono, including phase cancellation; ensure mixes sound good in both stereo and mono.

Stereo Expansion and Image Widening

  • Stereo width can be manipulated through the use of effects, plugins or EQ modifications.
  • Haas effect, or precedence effect, uses delay to create a psychoacoustic phenomenon of perceived spatial location.
  • Some plugins offer stereo expansion or image widening to enrich the perception of a wider stereo field, but extreme use can cause phase issues.