AUDIO: MICROPHONES AND POLAR PATTERNS
The first audio session in this week involved learning about the different types of microphones, what they are used for, and which ones are the most appropriate for particular shoots.
To begin, audio is arguably just as, if not more important than the visual presentation of a film. In a blog written about the importance of audio, L. Scott Harrell commented, ‘the audio is usually neglected because of the misconception that the success of a video production highly depends upon the quality of video.’ Even though there is no movie without the visuals, badly made audio to match the action on the screen will completely reduce the over all quality of the film. It is more likely that a movie with visuals of poorer quality yet outstanding audio will make a much better film. Another blogger rightly stated, ‘great sound can take a decent project and make it amazing. Without it, you may as well be playing static.’
Furthermore, an important thing to understand when dealing the audio within a movie is the concept of sound and sound waves. Sound is the energy things produce when they vibrate. It is much like light in the way it travels, as it must travel through a source. However, while light travels through a vacuum as that source, sound must travel through a medium such as air, water or metal for it to vibrate and hence, be heard. Sound waves are the way through which sound travels. It is often compared to the way ocean waves travel through the sea; they move from where the wind first blows onto the water, to the surface of the ocean and lastly onto the shore of the beach. However, a major difference between these waves and sound waves is that while oceans waves vibrate up and down, sound waves vibrate back and forth. This makes air bundle together in some places and spread out in others, subsequently making the sound travel to it’s destination.
Moreover, in film a microphone is the device used to record and enhance the sound of something that is meant to be put into the movie production. Different microphones do different things, and specific ones a chosen for a task depending on the speciality of it’s function. There are two main types of microphones; the Dynamic Microphone and the Condenser microphone. The Dynamic Microphone is great for general use and is extremely versatile. The build of the microphone is simple and very sturdy so that it can withstand rough handling and moisture. They do not require an external power source and are ideal for handling high volume levels. Dynamic microphones work when the diaphragm is hit by a sound wave causing it to vibrate. Attached to the back of the diaphragm is a coil of wire, called a voice coil. This coil moves through a magnetic field from a magnet on the back of the mic structure and generates voltage.
On the other hand, Condenser microphones are more commonly used in studios, especially as the are much more delicate. They are much more sensitive to sound than dynamic microphones and subsequently capture a lot more detail. In addition, this microphone does require a battery or external power source. As explained by the editors of MediaCollege.com, a capacitor (device used to store electric charge) has two plates with a voltage between them. A capacitor contains two plates with a voltage between them. In the condenser mic, one of these plates is made from a soft delicate material, and acts as a diaphragm (medium that forms partition.) Just like in the dynamic mic, the diaphragm vibrates when hit by a sound wave thus changing the distance between the two plates. This will increase the ability of the capacitor to store an electric charge.
Besides these two main types of headphones, there is also the shotgun microphone and the Lavalier microphone. A shotguns sound is picked up directly at the front of the microphone, so it must be positioned directly at its target. A Lavalier microphone for radio, motion pictures ad television productions and for when a lightweight, small, portable yet great quality mic is required.
Moreover, Polar Patterns of a microphone represent how effectively a microphone picks up sounds from different angles and locations. Some Polar Patterns include Omnidirectional, Unidirectional, Cardioid, and Super Cardioid.
Omnidirectional polar patterns pick up 360 degree sound. This means that they pick up sound from all directions and angles effectively without needing to be pointed directly at the source of sound. This would be very advantageous when recording the background noise of a scene, for example the general buzz of students at a school. A flaw of this microphone however, would be that as it picks up sound from everywhere, it cannot be pointed away to avoid unwanted sounds.
A microphone with a Unidirectional polar pattern picks up sound from one main point. It is quite the opposite to the Omnidirectional, as it ‘hears’ very little background noise. The person using the microphone must therefore speak directly into the point where sound is picked up, called the ‘voice side’ in order to get a quality recording.
A cardioid microphone is most sensitive to sound at the front than it is at the back. Like the Unidirectional, a lot of background noise is subsequently eliminated. Unlike the unidirectional however this microphone i=does have sensitivity both at the front ans the back, only one more sensitive than the other.
Lastly, the supercardioid microphone offers a narrower pickup than cardioids and a greater rejection of ambient sound. But they also have some pickup directly at the rear. Hence it is important to place monitor speakers correctly. Supercardioids are most suitable when single sound sources need to be picked up in loud environments
For the practical session, I was asked to record sounds that occured both inside and outside of the college, two with the microphone set to 150 and two with it set to 30.
To begin, the first set of indoor sounds that my group and I recorded were in a corridor, at the bottom of a flight of stairs in the college.In the audio clip that was recorded with a 150 degree polar pattern, the general background noise is a lot louder than the 30 degree one, and more detailed noises such as the talking of people are more noticable. Also, while the footsteps of a person walking up the stairs faded away quickly with the 30 degree polar pattern, it was heard echoing for longer with the 150 degree one. It may also be noticed that the sounds of the scrunching of a crisps packet and walking up the stairs are overly obvious and quite exaggerated in both the above clips. This is because the intention was to make the background noise a little more interesting, as well as to see how a specific noise would sound different with the two polar patterns. However, we later realised this was not necessary, as the exaggerated sounds are quite over powering, making it difficult to recognise the difference in the general sound of the surroundings.
Furthermore, the sounds linked above are recordings of the noise that is held inside a cafeteria. Unlike the previous indoor recordings, we did not create intentional noise for it to pick up, but instead left it to ‘hear’ the natural noise that surrounded us. Both pick up noise of the general sound of people talking, doors opening and so on. However, the 150 degree recording picks up more sound noticeably. It is louder and the range of noises heard is much more wide.
The background hum in the 150 degree recording is particularly noticeable compared to the other ones. Meanwhile, the 30 degree recording seems more direct and concentrated on a particular noise, such as the talking of people who were passing close to the recording device. This is evident in the 150 degree recording also, however a lot more indistinguishable noise is picked up along with it.
This audio clip was recorded a little way away from the smoking area, where many people were gathered. As the previous recording, the range of people talking was noticeably louder and more concentrated in the 150 degree recording than it was in the 30 degree recording.
For the next exercise I was required to create my own sound Foley, using things I found around the college.
To create this sound, I put the sink tap on so that just drips of water were coming out.
This was created by someone stamping their feet in one spot. This recording is honestly quite unrealistic, and s to loud and dramatic to be footsteps. It would have been more effective to imitate lighter steps,and put the recording device right by the feet so that it can be picked up even if the sound was too soft.
for the human voice, I recorded the general sound of people talking in a hallway. As direct dialog is usually recorded on set of a film, I thought it would be appropriate to record it as a background noise instead.
To create this sound , I used the sprinkling of a shower.
Lastly, the sound of a spaceship was created from the opening and closing ofan automatic door.
Video Entrepreneur Magazine (2016) Audio is more Important than Video Image Quality. Available at: http://vtrep.com/audio-is-more-important-than-video-picture-quality/. (Accessed 03/10/16)
Woodford, Chris (2014) Available at: Sound – The Science of waves, how they travel, how we use them. Available at: http://www.explainthatstuff.com/sound.html (Accessed 03/10/16)
Desktop-Documentaries.com (2016) Different types of microphones. Available at: http://www.desktop-documentaries.com/different-types-of-microphones.html (Accessed 03/10/16)
Wavelength Media (no date) Dynamic Microphones. Available at: http://www.mediacollege.com/audio/microphones/dynamic.html (Accessed 03/10/16)
Yamaha Corporation (2016) Microphone Types. Available at: http://www.yamahaproaudio.com/global/en/training_support/selftraining/pa_guide_beginner/microphone/ (Accessed 03/10/16)
About, Inc. (2016) Condenser vs. Dynamic Microphones. Available at: http://homerecording.about.com/od/microphones101/a/mic_types.htm. (Accessed 03/10/16)
Home Studio corner (2016) Why You Should Use a Condenser Mic on Vocals. Available at: http://www.homestudiocorner.com/condenser-mic-on-vocals/ (Accessed 03/10/16)