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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, record instruments at home, or other highly artificial settings. 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 e.g. 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, i.e. 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).

There are differences in sensitivity among microphones, some of them having to do with the type of microphone – dynamic, condenser, etc. – but this goes beyond our needs. Basically condenser mics are more sensitive than dynamic ones; because of the way they use electricity they can use a lighter-weight diaphragm, which is activated by a smaller sound pressure. (The larger the diaphragm, the more sensitive the condenser mic, but also the larger the mic itself.)

 

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, but it may affect mic placement.) 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 ALC (Automatic Level Control). Isn’t it safest just to use that?

No! Well, sometimes it gives Ok results. But the recorder (and ALC) is just a dumb machine. It doesn’t know which sounds you want. If a truck goes by while you’re getting a great interview on the street, the ALC will lower the level so that you get a nice, listenable recording of the truck’s roar – but your and the speaker’s voices will drop down to nothing. Don’t trust the ALC; figure out a general beginning setting for your recorder – check that the recorder is on when you take it out of its case to start; and then make any needed adjustments.

 

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. High-quality mics like the ECM-44BC) usually have a 3-pin male XLR (or “Canon”) conector, for which you can buy standard cords of good quality and any length. Another option is a cordless mic, which sends signals wirelessly – good ones are not cheap, and have their own (transmission and reception) problems and learning curve, 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 and T's into it, 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 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…

 

Rode Lavaliere microphone

=£138

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

 

For music recording I have also used classic microphones such as the Shure SM58 (dynamic, cardioid) and ElectroVoice 635A (dynamic, omni) for vocals etc. - but not for sociolinguistics.

 

Notes on the above:

          The Dept has just (2016) bought some new Rode lav mics for use with the new Marantz PMD-661 Mk II solid-state recorders, so will report on them soon.

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 1-metre-long 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! Test it to make sure it plugs in easily and securely. 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: Here’s a decent short page on microphones for beginners: http://www.explainthatstuff.com/microphones.html. The illustration really lets you see how they work.

*NB: Here's a link to another 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.

My contact info. Thank you!

 

LG554 Sociolinguistic Methods page

Peter L Patrick’s page on recording media

Peter L. Patrick's home page

Last updated 07 October 2016