Training for TV



Knowledge for TV Professionals

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Things you might not know about sound and audio...

  • Pitch is the musical term for frequency. However, our perception of musical pitch is not related to frequency in a linear way.

  • Our perception of loudness is also non-linear. This is why we use decibels to measure level, because it is a logarithmic scale. A good rule of thumb is that if signal voltage doubles, the level increases by 6dB. As an example, a signal measured at 50dB will double by 56dB and halve by 44dB.

  • Our perception of direction in sound is based on our two ears. They are able to work out direction by two main means... relative loudness and time of arrival in each ear. This is also the basis of stereo and multi channel audio systems.

  • EBU stereo ident tone is used to make sure that our stereo signals do not get switched. It uses two 1KHz test tones, with intermittent breaks in the left leg. The BBC also has it’s own stereo ident tone... it too has breaks in the left leg, but each break is then followed by two breaks in the right leg.

  • Most broadcasters peak their audio at -10dB(fs) or -12dB(fs). This is at least 10dB below the highest value digital audio systems can handle. This means that there is spare capacity to cope with unforseen circumstances e.g. a presenter sneezing, or for slight inaccuracies in metering without causing distortion to the audio.

  • Low frequency sounds will diffract around all but the largest objects, meaning that they appear to have little directionality and makes them very hard to control. It is why we will hear the bass drum from the rock concert or night club a long way from the venue and long before we hear any other sounds.



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  Training for TV Ltd.
Rutlands, Main Street
South Littleton
WR11 8TJ
United Kingdom
+44 (0) 1386 832801



Knowledge for TV Professionals