Microphones
Although the range of microphones available is extremely wide. the choice is at least narrowed once the collecting centre has decided what recording equipment it should use. As a general rule it is a waste of money to purchase an expensive microphone for use with a cheap recorder and equally improvident to buy a poor quality microphone for employment with a high quality recording machine. The best relative results are obtained when the two items are of a complementary standard.
The cheapest microphones - those falling within the price range of, say, £2.00 to £10.00 - tend to have an uneven frequency response. As they react less sensitively to the higher and lower voice frequencies they often result in a rather 11at recording on which the full speech range is not represented. Such microphones also frequently emphasise and distort on the tape voice sibilants and hard consonants such as p's and b's: the former produces recordings on which the voice sounds very harsh and the latter a sort of popping effect. These distortions very often occur when the microphones sold with some of the cheaper recorders are used. In such cases the overall recording quality may be slightly improved by buying a separate and better quality microphone.
Some microphones are more prone than others to what is termed "handling noise'. This is noise caused by friction of the hand against the microphone case stand or cable. With clip microphones the effect also occurs through the microphone or cable rubbing against the clothing of the person it is attached to. This problem is insidious because handling noise is completely inaudible when the interview is being recorded but on playback is reproduced as thunder or loud crackling and can devastate the recording.
In addition to complementing the quality of the recorder, these are certain principles which should be followed in selecting a microphone for interviewing purposes. They should be small and light for easy porterage and unobtrusive use but sufficiently robust in construction to take minor knocks without damage to their performance. A sensitive and even response across the voice frequency range is needed but they should be insensitive to handling noise. Table microphones should also have a directional pattern which gives them a ~blind' side that can be faced to any extraneous sound sources which may be evident in a particular recording environment.
There are two general types of microphone construction which can be considered for interview recording. These are the moving coil (more commonly referred to as the dynamic type) and the electret capacitor microphones. The moving coil is by far the most common type available. It is manufactured in various forms, the different characteristics of which are mainly concerned with directional sensitivity. For interviewing, the most suitable pattern is provided with the so-called uni-directional or cardioid type of microphone. These will discriminate against sounds striking the back of the microphone and. thereby provide a degree of protection against some unwanted noise. They are, broadly speaking, equally sensitive to sounds from the front or sides of the microphone
Electret capacitor microphones are quite a recent development and, like the dynamic types, are available with different directional characteristics. Their principal advantage is that they combine an extremely high performance with a relatively modest price. In these terms -of cost relative to quality -microphones of this kind represent remarkable value for money. Interviewers who are generally uneasy with recording equipment, may be put off by the additional impedimenta of the miniature batteries and amplifier needed to power these microphones. However, since they are up to 50% cheaper than dynamic microphones of comparable performance, there is a strong financial incentive for overcoming any such prejudices.
Clip microphones are particularly suitable for interviewing purposes (see also Chapter 5), especially when they can be separately provided for both the interviewer and informant. They permit close microphone placement without disturbing the informant in the way that the more obtrusive types of larger microphones sometimes do. This enables the interviewer to minimise many extraneous sounds, by setting the recording level at a point where such noises are significantly diminished, but which is at the same time sufficient for satisfactorily recording the voice. Acoustic problems are also conveniently reduced with this kind of microphone, since it is so close to the speaker that his body shields it from a great deal of the reflected sound. As clip microphones can be attached to a stable part of the speaker's clothing, their use also obviates variations in the recording level which often occur when informants change their positions relative to a table-mounted or other fixed microphone.
Until the advent of the electret capacitor type, clip microphones - except some very expensive studio models - tended to be relatively bulky and to have a somewhat lower technical performance than conventional microphones. The introduction of the electret type has led to a significant further miniaturisation of models and at a cost that brings them within the range of many historians.
Among the electret capacitor clip microphones, the Sony ECM 50 -now in wide use within the broadcasting industry - is a good though expensive (at about £100.00) choice for use with professional and semi-professional recorders. There are, however, other makes available in the price range of £15.00 to £30.00 which give excellent results. These are marketed by various companies and the Sony ECM 150, Lawtronics LM23 and Eagle PRO M60 are among the best known in Britain. Table microphones, of the dynamic type (cardioid pattern) referred to earlier, suitable for use with recorders in the category of the Uher series and cassette machines of comparable performance include the AKG D190 (approximately £40.00) and D200 (approximately £60.00) and the Beyer M81 (approximately £30.00) and M69 (approximately £60.00). The electret capacitor microphone is also available in tab1e versions with the cardioid pattern recommended for interviewing purposes. These are manufactured by various companies including Sony and Eagle and are somewhat cheaper (£12.00 to £40.00) than dynamic types of comparable performance. Oral historians using relatively cheap cassette recorders would be advised to seek the advice of equipment manufacturers or a specialist retailer, whilst also bearing in mind the general guidelines given in this section.
