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Beginners’ Notes about Using Microphones
by Peter L Patrick
Notes for LG554, Sociolinguistic
Methods I
I’m no
expert on microphones or recording [see notes* at
bottom], but I have done a few hundred interviews, group sessions,
etc. with cheap to moderate to somewhat expensive equipment, since the 1970s. I
normally advise beginning fieldworkers to buy their own microphones (and
recording equipment, if possible), since they need not be expensive to give
good results. Microphones and their placement probably make more of a
difference to getting good sound from an interview or group recording than
anything else, and you can make great improvements over a poor hand-held or
built-in one just by getting and properly using an inexpensive (£15-20)
lavaliere or tie-tac microphone.
I sometimes get questions from
students about this stuff. Here are some that may be useful.
All the advice I’ve gotten or found is about how to
get great sound in a lab or highly artificial setting. Is this our goal?
No. Good
point. Of course, if you are doing psycholinguistic experiments in a lab, or
collecting word-list or other highly artificial materials from speakers for
acoustic analysis, then yes – nothing you do will make it a natural
conversational setting (in fact you probably don’t want to), so you might as
well get the best sound you can, even if your speakers find it a bit irksome to
be manipulated around.
But that’s not what I assume here.
I assume you are a sociolinguist collecting
speech you hope will be easy, relaxed, in comfortable settings familiar to the
speaker – and which will not be ideal for sound recording. Your task is to do
the best you can in these circumstances, and only manipulate the speaker when
you absolutely have to. This affects eg choice of recorder (small is good so
they won’t notice), mic (out of sight, and again small is good), cords etc.
(none is good, ie wireless - or just long enough for them to not notice – and
for you to stop them when they get up and wander off, before they drag your
equipment with them!).
My
question/problem is that in trying to get samples of speech, I just wish my mic
picked it up stronger.
With
microphones, as I understand it, it's mostly about directionality,
not about "strength". So what you
want is to
§
get
your mic as close as possible to the sound source
§
(without
making the source, if it’s a human, uncomfortable),
§
have
it pointed in the right direction
§
(if
it has one – some mics are omni-directional),
§
have
nothing in the way or touching the mic (eg, clothes), and
§
have
no other, unwanted sources of sound anywhere near the mic
§
(ie, near the speaker).
How do I set the recording levels?
The other
main variable is the recording level (sound input
level), which can usually be set from a recorder. (It’s often set by
using the volume control, which only works during playback for volume; of
course, rec level only works during recording, and is similar to volume. Check
your manual.) This is a manual adjustment to the strength of the signal that is
being recorded. (It doesn’t actually change anything on the mic, just in the
recorder.) If this is set too low, you will under-record
and the signal will be too weak; if it’s too high, it will over-record and distort the sound (eg “clipping”).
This needs some experimenting with so that you get a general feel for setting
it. Some people like to check it in every situation before, or at the beginning
of, recording. I think once you get a good feel for it, this won't always be
necessary, and of course it can make people more self-conscious, though it
needn’t.
My recorder has
No! Well,
sometimes it gives Ok results. But the recorder (and
I bought a mic with a really long cord, so if my
speaker moved or jumped up it wouldn’t strangle them. I thought that was a good
idea, don’t you? It was still pretty cheap.
Well, yes and no. It’s important to
make them comfortable. However, another variable in sound quality is the length of the mic cord – also the quality of the connectors. The signal traveling
down a mic cord is very small, electrically speaking, and on a long cord or a
thin one it "leaks" and attenuates. Some materials
of which the connecting surfaces of mic plugs are made, are better than others;
gold is the best. More expensive mics thus have better cords and connections,
and this does make a difference. Another option is a cordless mic, which sends
signals wirelessly – good ones are not cheap, and have their own (transmission
and reception) problems, but can be invaluable if you are, e.g., recording
patients and doctors in a clinic, police officers on duty – anyone who must be
able to move unconstrained.
What’s the single most important thing to get right?
If I had
to guess, I'd say the commonest error in beginning recordings is mic placement: usually, not getting the mic close
enough. The best place to attach a lavaliere mic
is right up under the throat, attached to clothing that doesn't rustle (silk shirts
are terrible!) and doesn't get in the way, and pointing up. Then it's near the
larynx where the vibrations are created, also the resonators in the mouth and
head – and plus, it's out of the speaker's sight so they won't be looking at
it, touching it, spitting their S's and P's andT's into, or remembering it's
something they're speaking into. But this is a private part of the body, for
good animal reasons (the jugular vein etc.), and placing a mic there in a
calming, non-invasive way can take a bit of practice, especially where there
are cross-sex, -age, and –cultural contrasts between speaker and fieldworker. Head-mounted mics tend to be movable, in a
vertical arc from below the chin to above the eyebrows. Both are good
positions, but below the chin is also invisible to
speakers, which is good. In radio studios, the engineers (who have massive
experience) often prefer to have you speak into mics which are mounted level
with the top of your head – but you are staring at them the whole time…
Is there
some kind of super-mic that is more powerful or somehow picks up sounds more
strongly?
There may
well be. Certainly there are highly directional
mics, usually long cigar-shaped things that cost a great deal, and that
you have to be very precise with aiming. I don't know anyone who has ever used
one in sociolinguistic work though. You often find fieldworkers using omni-directionals, or cardioids
– with heart-shaped recording fields, ie a little dead area just 'behind' the
mic, where the cleft of a heart is – or super-cardioids,
a variant of that. For our purposes though, in a lavaliere mic, I can't see
that it makes much difference, as long as you point it at the person. (A
cardioid, as I said, does have a slightly dead area behind it, to reduce the
volume of the interviewer – if you don’t want to do that, use an omni!)
It is also possible to use hand-held mics and aim them precisely in front of
the speaker's mouth. But this has lots of difficulties – trusting a speaker to
stay the right distance/angle (few people know how to do this), or constantly
moving it around and distracting them, or forgetting yourself to hold it up.
Plus it's always dead in their glance and makes them very self-conscious; and
you get more noise from sibilants and stops. (Singers who use mics have to
learn how to control their S’s, P’s and T’s, etc.) Not worth the trouble except
for a setting which is intended to feel like a laboratory, to capitalize on
high self-consciousness, eg in a language test.
Here are
a couple of models and prices of mics I’ve
purchased. The prices are some years old, and I can’t search supplier info or
quotes for you – sorry. Nor is this a commercial endorsement, etc. (though
you’ll see that I’ve typically bought Sony equipment; however if anyone
wants to give me free mics or equipment, please contact me!). But it may give
some idea of the range of things commonly used by students doing
sociolinguistic field recordings. Note that these are NOT the kinds of
microphones you'll see recommended on music sites, for the reasons above –
those are obviously good too, but have the problems identified above…
|
Sony ECM-55BC lavaliere
microphone |
=£172 |
|
Sony ECM-44BC lavaliere
microphone |
=£92 |
|
Sony ECM-717 stubby condenser
microphone [Notes: 3-ft cord, bulky,
uni-directional, stereo, w/stand; -55 dB] |
=£90 |
|
Sony ECM-T110 lavaliere
microphone [50-10k hz, omni-directional, 3ft
cord, alligator clip- points wrong way!] |
=£40 |
|
Sony ECM-T15 lavaliere
microphone |
=£40 |
|
Sony ECM-T6 lavaliere
microphones |
=£20 |
Notes on
the above:
I’ve used the 44BC extensively for
years and been very happy with it – it was worth every penny (to the Wenner-Gren
Foundation who bought it for me!). Some mics have 3-ft cords – for our purposes
this is very short indeed and usually it doesn’t work for interviews where you operate
the recorder. “Bulky” is bad. “Stereo” sounds like a good thing to have – but
actually, two separate mics (1 for each channel) is much better than a “stereo”
single mic, because in the latter the separation is never more than an inch or
so! Students have gotten good results with the cheapest one above, the ECM-T6,
though not great – and all good results require some practice.
It also makes a lot of difference what sort of connection your mic makes with your
recorder. A good recorder will have balanced inputs, and a choice of inputs for
different mics. Cheapo ones have neither. Know what type of connection your
recorder has when you buy a mic! Otherwise you have to have a converter of some
sort between them – it will loosen and fall out, and even if it doesn’t, sound
energy will leak away, or a poor connection will degrade audio quality.
*NB: The
*NB: Here's a link to another beginner page on microphones. It's aimed at
music home recording, but explains things well for beginners.
http://homerecording.com/mics.html
Let me
have anything, please, that can help my students and improve this page:
corrections where I’ve got it
wrong, new questions I haven’t answered, etc.
Email to patrickp@essex.ac.uk. Thank you!
LG554
Sociolinguistic Methods page
Peter L Patrick’s
page on recording media
Last updated 19 October 2009