Improving audio quality with digital microphones and digital wireless

Recording sound for television presents a number of challenges. One goal is intelligible speech, and this calls for good separation between the voice and background noise. In free space, sound intensity falls off according to the inverse square law, so positioning the microphone close to the source is vital. For genres like drama, microphones and their cables should not be visible, and this demand can conflict with the need to get microphones close to their sound source.

Heard, but not seen

The primary means of recording is the boom microphone, which is close to but out of the shot. This requires a skilled operator who can work closely with the cameraman. Concealed microphones can also be used, covered by clothing or hidden in props. For most genres, they should be discrete, which means sub-miniature and wireless.

This need to avoid the microphone being overtly visible or not visible at all inevitably leads to compromise. Equalization in the desk can hopefully compensate for sub-optimal microphone positioning. Other tools, including special dialog noise-reduction filters, can also assist in the capture of clear dialog. Clip-on microphones usually come with a rising frequency response that improves treble response. This counteracts the loss of high frequencies when the microphone is hidden underneath a costume.

Technology advances and developments, like surround sound, add to the complexity of audio capture. But, digital processing, wired and wireless, gives sound recordists new opportunities to capture higher-quality sound.

Recent advances have focused on wireless as live events become more complex. Wireless frees talent from trailing cables, but available spectrum is shrinking as mobile service providers buy up capacity in bands traditionally used for wireless microphones. Consumer technology is advancing, and developments such as surround sound have added to audio capture’s  complexity.

The director of a live event will want the sound designer to capture a setting’s excitement and add it to the drama. It is no longer adequate to have a crossed pair of microphones capture  crowd ambience, and a lip or headset microphone for a commentator.

Sound design for sports production is an integral part of the TV experience, and even more so in surround. Sound is used to capture the excitement of the crowd, helping to deliver the director’s concept of sport as compelling TV entertainment. Audio must also capture action, and that means microphones must be close to the play. Digital technology is being used in new areas to help sound designers. One development is digital wireless, while another is the digital microphone.