13 Mics: practical listening exercise (b): mic placement and sound discrimination
One ear
This exercise furthers your ability to appreciate the nature of ‘one ear’ – a mic capsule – substituting for both human ears in the real world – the essence of balancing on location. For this you will need two differing sound sources about six feet (2 m) apart. I suggest using your radio and television, since you can easily change stations/channels to give you a variety of sounds to experiment with. Set both to deliver as equal a volume of sound as is practical, and mount your mic on a pole.
At this stage you don't need closed headphones, since it's useful to discover how the overall sound direct, versus the sound via the mic/headphones combination, sounds to you as you move your mic, a more true-to-life recording situation. Monitoring and recording your results, as per Section 12, Mics: practical listening exercise (a), start with the mic as far as possible and equidistant from both sources, and move it slowly towards the loudspeaker of one of the sources. Hold it in this position for a few seconds, then move it slowly across to the loudspeaker of the second source and again hold it in position for a few seconds.
Perform this exercise first with an omni and then with a gun mic (if you're recording your results, remember to verbally ident each part of your recording with which mic you're using). When using the gun mic, keep it pointing directly towards the first source for the first part of the move, hold it stationary for a few seconds, then angle it towards the second source before once more moving it across to it and holding it stationary.
Notice how the sound from your selected source becomes more intelligible/clearer the closer the mic gets to it, and the difference between the omni and the gun mic. Working either mic close to one source enables you to virtually exclude all the sound from the other. But, notice how much more control you can achieve with the gun mic via the angle at which it's placed. However, do you always need to cut out as much extraneous sound as this? Don't forget that the secret of using one mic on location is to establish a balance between intelligible sound whilst retaining an ambient aural ‘flavour’ of the surroundings (see Section 14, Sound balance and location acoustics).
You may find it useful to repeat the exercise with the gun mic to determine how it responds at differing angles and distances from each individual source. Try varying the distance between the sources, and adjust your mic position to give an indication of the relative distance between the sources.
The recording
Play back your recording, listening on a loudspeaker, and judge how successfully you've achieved a balance between the two sources. Does it sound exactly as you had expected/intended?
The ideal way to complete this exercise is with a camera and cameraman, during a social occasion (friends round for a day, out on a shopping trip, etc.). Before you have a lot of experience, it's best to work alongside friends, who'll put up with you waving a mic at them. You can work with the mic plugged directly into the camcorder, or via a mixer to the camcorder, but do ensure you monitor the sound feed correctly on your headphones via camcorder or mixer. If time and circumstances allow, try the exercise with both mics.
First agree with the cameraman a sequence of people you're going to speak to, and have him approach each in turn and ask a question (you can always fall back on the hoary old standby ‘What did you have for breakfast?’ if all else fails). This is the equivalent of shooting vox pops, and is certainly a skill you'll need to acquire if you aim to work in broadcasting.
Once you can keep up with a pre-arranged order for the participants, get your cameraman to approach people randomly, and see how quickly you can get the mic in position so that:
You can hear intelligible speech.
The background sound gives the correct aural ambience for your surroundings (and matches the pictures).
You constantly maintain the correct balance between the two.
The overall sound level you record is correct.
To make yourself work really hard, see if you can position the mic to hear the question and then reposition sufficiently swiftly to hear the full answer (and without any mic/pole handling noise being apparent). A final word of advice: don't replay the results in front of the others until you've had a look and listen for yourself! Nevertheless, when you do so, the comments you receive can often help further your understanding of other peoples’ expectations.
Further listening
Both exercises (a) and (b) should be repeated from time-to-time when you have different mics to test, and to gain confidence in your ability to produce consistent recordings. See also Sections 20, Single person operation: tracks, levels and practical exercise (c); and 25, Sound recordist operation: practical exercises (d) and (e).