BBC Radio delivers a diverse range of programs to its listeners via terrestrial and satellite transmission, online streaming and downloads. An underlying requirement for all programs and delivery methods is that the audio quality heard by the listener is consistently high.
Audio quality may be defined by a combination of objective parameters – bandwidth, peak level, digital bit depth and so on – plus a range of subjective elements. A listener’s judgement of audio quality will depend on their own listening environment, equipment, expectations and their sensitivity to various kinds of imperfections.
For audio content to be considered high quality, it must meet certain minimum objective standards and be free from subjective impairment that is likely to reduce listening enjoyment for a significant number of listeners.
The factors that affect audio quality can be divided into four main categories:
Environmental (for example venue acoustic, ambient noise)
Technical limitation (for example microphone quality, restricted signal path bandwidth)
Operational practice (for example microphone placement, loudness, peak level control)
Fault conditions (for example dropouts, clicks, hum)
There is naturally some interaction between these categories: For example a change of operational practice might be used to overcome a technical limitation and reduce the likelihood of a fault condition arising.
Audio should be captured and transported throughout the broadcast signal chain in a lossless digital format (e.g. linear PCM, FLAC) wherever it is practicable to do so. Where circumstances require the use of lossy bit rate reduction, care must be taken to maintain acceptable subjective audio quality.
Listening to the BBC CDs is a true audio event. The CDs are quite nearly, as a group, the best recorded CDS today even at multiple times this price point.