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The Physics of Microphone Placement and Reinforcement

Microphones are transducers which convert energy in form of electric current to sound. The sound is a product of variation in air pressure. Such air, when fed into a microphone as a person speaks of it, is converted to electric currents which are then transmitted to the amplification systems to produce a louder sound (Nisbett, 42). Within the microphone there is a diaphragm that vibrates when struck by the air waves. The vibrations are then converted to electric current and ultimately as sound. The mechanism of functioning of a microphone may sound basic. However, its performance is highly detailed and a trivial alteration in design may result to a massive variation in the quality and type of sound produced. Microphone designers, therefore, pay exquisite attention to detail when developing these instruments.

The quality and type of sound produced by a microphone depends not only on the type of microphone but also on an array of other factors. It depends on the distance between the microphone and the speaker, the room or stage of performance and availability of other instruments among other factors. These instruments may either interfere with the performance of the microphone or improve the quality of the sound produced by the same. For these reasons the placement of a microphone to derive the maximum and intended quality of its use depends in part on the environment, the place where the microphone is located. For an individual, the microphone performs best when held close to the face. However, for a group of people, such as a band, other factors come in, since it is not only one person projecting sounds over the microphone. A suitable microphone for this case would be a boom microphone (Burrows et al., 66).

This microphone can pick up sound vibrations from a distance away. Frequently preferred by news anchors when holding interviews, this microphone allows for the perception of the sounds produced around it. Its high sensitivity also means that it could likely pick up unwanted sounds, handling noise, breath sounds and vibrations among others. For this reason, various mechanisms such as foam padding are employed to minimize on effects of stray sounds. That is the same reason why it should be a consideration in the band use. The placement of the microphone is also of great importance.

In the case of a band, sound frequencies may be coming from more than one direction. Bearing in mind that sound is unidirectional, placing such a microphone in the center of the band circle allows the sounds produced by each member of the band to be perceived and transmitted. This also highlights the need to employ the use of unidirectional microphones, especially for large bands (Burrows et al., 72).

Microphones, such as the cardoid and hypercardoid, can virtually receive sounds from all directions. The microphone should not be placed more than eighteen inches from each of the band members. At the same time, it should be at least twelve inches away from the performers. The sound produced travels from various sources and from different directions and is taken up by the microphone which perceives it as air waves of different pressure. The instruments that accompany performances and productions also need to be strategically placed so as to obtain the desired effects of all instruments together with the microphone. If not properly arranged, the acoustic effect may take place.

The acoustic effect occurs when a sound produced from the loudspeakers finds its way back in the amplification system leading to the merging and thereby confusion of the resultant sound. This can be corrected by equalization, a process which involves selective masking of frequencies so as to remain with the desired frequency and thereby sound (Huber et al, 54).

Chamber music usually involves a few people who play musical instruments either to a large crowd or for personal pleasure. Even when played in front of large crowd, personal pleasure derived from the performance by musicians is crucial to them. Chamber music also requires the use of microphones and especially so when performing to a large crowd. In such an instance the placement of the microphone becomes an essential factor to consider. This is because of chamber music, as previously mentioned, involves the performance of more than two musicians playing instruments. Since vocals are rare in this kind of music, the microphone is basically for amplification of the sound produced by the musical instruments. To begin with, performers in a chamber usually need to sit some distance from each other so as to minimize the effect of masking and to allow each player to get his or her sound to the microphone. For this reason, more often than not the performers sit in a semi-circle. If other equipment such as the piano and viola are to be used, space has to be accorded to these, too so as to allow for uniform perception of the sound (Huber et al., 27).

The microphone is to be placed in the middle and the engineers need to make sure that all the instruments can be perceived by the microphone and they all are audible before the show begins. In chamber music, the microphone is usually placed about twenty inches from performers. Consideration of the room or stage is also to be made. It is necessary to ensure that the instruments and the performers are equidistant from each other and the walls so as to avoid irregularities and echoes (reflection of sound produced). This is because most of the musical instruments used in this case, such as the violin, produce high-frequency sounds. When fed into the microphone, such a sound may come out as irritating noise rather than good music. Thus, the distance allows for a good enough amount of air waves from the musical instruments to reach the microphone. At the same time, central location and twenty inches away from the performers ensure that high-frequency sounds from the instruments are not transmitted directly to the microphone. The sound reinforcements also need to have the high precision of intelligibility, balance and loudness in order to end with a cognizable musical performance (Wilson, 78).

The placement of a microphone with regard to the soloist is dependent on a number of factors. To begin with, size of the room and audience has a bearing in this. For performances involving large audiences, the soloist may be required to be closer to the microphone so as to cut down the interference of air waves and thereby sound. The distance of the soloist relative to the rest of the performers or choir also comes into play. If the overriding factor should be the voice of the soloist, then the microphone should be placed closer. However, if the contribution of the whole choir is needed, the microphone should be placed centrally and the same distance away from all of the choir members. At the same time, the question of whether the soloist is playing a musical instrument or not comes into play.

If the soloist is playing an instrument, say a guitar, consideration has to be made on how much of the sound from the guitar needs to reach the audience. If the instrument played by the soloist is a piano, it is advisable to place the microphone about eight feet from the soloist. On the other hand, if the soloist is not playing any instrument, then a distance of six feet from the microphone would do. From that distance the voice of the soloist is able to be concentrated and projected to the microphone and, therefore, it produces the lead voice required of a soloist (Nisbett, 52).

Two types of microphones, wireless and the wired have been developed to improve the user experience of employing these gadgets in their trade. A microphone has to be backed up with an amplification system if the sound fed into it is to be magnified. The wireless microphone differs from the wired one in this context. Whereas the wired microphone has to be connected directly to the amplifying system for the desired magnitude of sound to be achieved, the wireless microphone does not hold the same. Unlike the wired microphone, the wireless microphone has a special transmitter located within the microphone itself. The transmitter receives signals after they have undergone transduction and transmits them to the amplifying system without involving the use of a wire or a cable. The amplifying system is also equipped with a wireless receiver which receives signals from the transmitter. Usually, the wireless microphone employs the use of a battery (which could either be rechargeable or not). This means that even without the luxury of power, it could still be able to work. The main question, however, is will the rest of the system, including the amplification system, be able to work without power? One other advantage that the wireless microphone has over the wired microphone is its portability. Since it is not physically connected to the amplifying system, the wireless microphone allows the user to move freely. For this reason, it is widely preferred by performers who indulge in a lot of movement during their performance.

The wired microphone, on the other hand, limits the user to the distance within the length of the wire that transmits the sound to the amplifying system. The wired microphone allows the user to mike other musical instruments. It also allows the user to counter the effects of unexpected interferences, such as vibrations. The user only has to draw the microphone away from these agents. Above all, the wired microphone comes at a lower price than the wireless one whose technological advance calls for a parallel high cost. The wired microphone is a better option compared to the wireless one despite the latter being more convenient in terms of portability. The advantages of the wired microphone far outweigh those of the wireless microphone, especially with regard to performance (Nisbett, 78).