3.2. Recording techniques
Capturing a signal to tape or disk clean of excessive reverberation or noise is critical. You can always add effects later to enhance or alter a sound, but it is difficult to remove distortion and noise from the original source. Compression in the encoding process also degrades your sound slightly. The higher the quality of the original source material, the higher the quality of the final output to the Web. In addition to selecting the right equipment, properly setting up your studio and reducing noise on location also results in a cleaner signal.
A studio environment is optimized for the best possible acoustics in music and voice recording. In a typical studio situation, you also work with well-rehearsed, professional voice or music talent and have access to a wide selection of high-quality microphones and effects processors.
In contrast, field recording requires capturing sounds in less than optimal conditions. Because most field recordings take place outdoors, it is difficult to prevent poor acoustics and the intrusion of extraneous noise. Furthermore, in a field-recording situation, your equipment is limited to a set of microphones and a small portable DAT machine, making it likely you will capture spontaneous, unrehearsed dialogue and sounds.
For both environments, there are recommended ways of dealing with unwanted sounds.
3.2.1. Studio recording
If you are recording voice or music talent on a regular basis, you will want to reconfigure an existing room to optimize the acoustics, or better yet, build a new room specifically designed for audio recording. A good sound studio should have optimal acoustics for music or voice (as described later in this section) and isolation from extraneous noises.
Ideally, your studio should isolate recording and engineering activities in separate rooms. This completely removes equipment noise from your recording environment. If you have only one room for recording, mixing, and monitoring your sound, implement some or all of these suggestions:
126.96.36.199. Proper room acoustics: capturing a "dry" signal
We perceive spatial distance audibly by the direction or angle of strong sound reflections. Minimizing reflections in your studio prevents these unwanted "directional" clues from being permanently imbued on your source recording. If you record a direct signal with as little reflection as possible, you can add artificial reverberation to recreate any acoustic environment. For voice-over work, recording a " dry" signal without reverberation provides the maximum flexibility to "sweeten" the sound with digital effects in the post-production process. If your source recording has highly distinctive characteristics, it is nearly impossible to remove those reflections in post-production.
To determine the characteristics of your room, try this simple test. Wait for a quiet moment and clap your hands loudly or yell. Listen to the amount of reverberation and reflections produced. If you hear an echo or large amounts of reverberation, consider using a different room entirely. If you hear a pitch or a ringing sound, a fair amount of acoustical treatment will be needed. An example of the use of acoustic foam is shown in Figure 3-6. If you hear only a slight echo or reverberation, which will be the case in most small, carpeted rooms in an office or home, you will need to make only a few minor adjustments to achieve good acoustics.
Figure 3-6. A recording studio with a small strip of acoustic foam placed in the corner to dampen unwanted reflections
188.8.131.52. Optimizing your recording environment
Isolating your studio from outside street noise is difficult. Anywhere air can pass into your studio -- under doors, through cracks in window panes -- noise will follow. You can reduce the intrusion of most high-pitched frequencies by placing rubber sealing strips along the sides of doors and windows and patching any other spots in your studio where air can pass through. Isolating your studio from bass frequencies is far more difficult. Unlike most high-frequency sounds, bass frequencies travel easily through walls.
True isolation from the sounds of passing cars or airplanes is achieved by constructing a room within a room where the walls of the outer room contain substantial mass, and the inside room is carefully isolated or physically disconnected from the walls of the outer room. In most cases, this process is far too expensive and laborious for small-scale audio production. If you are recording in an urban environment, select a room in the middle of a building or one with extra-thick walls.
The problems that arise from recording in small rooms are associated with unwanted reflections and echoes. Hard, flat surfaces, such as hardwood or tile flooring, bare sheetrock or cement walls, and glass windows are problematic because they reflect a slightly delayed copy of the original sound back to the microphone (in the form of an echo). This echo effect can be exacerbated if the sound is further reflected between parallel walls.
Placing thick acoustic foam on strategic spots on walls and ceilings is the easiest solution to reduce reflections. The usual strategy is to place foam opposite bare spots in a checkerboard pattern. The most common mistake is to use too much foam, which leads to unwanted bass build-up, since foam has little effect on low frequencies. If you cannot afford acoustic foam, you can improvise with additional wall hangings, rugs, bookshelves, and other furniture, as well as with pillows, blankets, or mattresses. These accessories help absorb the sound waves and create diffuse surfaces to reflect the audio away from the microphone.
184.108.40.206. Desktop audio recording
Managing your studio's acoustics, microphone placement, and recording talent are the more difficult aspects of studio recording. Actually getting the sound onto your desktop is easy. Most sound recording and editing applications use familiar tape deck controls, such as play, record, pause, and stop. Macromedia SoundEdit 16's controls are shown in Figure 3-8. You'll also note a less familiar button -- the loop control -- activated; it continually repeats the selected audio.
Figure 3-8. The controls window in SoundEdit 16 with (from left to right) record, stop, pause, play, and loop buttons
The most important control in the recording process is the recording level. In SoundEdit 16, this control is located under Menu Windows Levels, and is shown in Figure 3-9. If your microphone is plugged into your computer and your sound card is properly configured, you will see green LED lights bounce up and down as the microphone picks up the signal. The green light represents the signal as it approaches 0dB; the red light indicates that the signal has gone over 0dB and is distorting your audio. Adjust the levels as you test the microphone placement until the signal stays completely in the green. We explore using SoundEdit 16 more in Chapter 4, "Optimizing Your Sound Files".
Figure 3-9. The Levels window in SoundEdit 16
3.2.2. Field recording
Of course, not all the audio on your web site will be recorded in a studio environment. Capturing audio on location complicates matters considerably. Field recording requires the use of a lightweight, portable DAT machine with phantom power and high-quality built-in mic pre-amps. Microphone selection and placement are especially crucial to capturing good sound on location. A few steps that also make for a positive experience include packing a foam microphone covering or windsock to protect against wind, carrying a backup microphone with an alternate pick-up pattern, or simply moving the microphone closer to the sound source. The following sections include some recommended methods for capturing sound in different scenarios.
220.127.116.11. Live concerts and events
There are two primary methods for recording the sound of live events and concerts: capturing the live stereo output of the public address mixing console or placing two condenser microphones in front of the stage or PA speakers. Capturing the mix from the PA console is more convenient, but using your own microphones generally results in a higher-quality recording.
All amplified events have some type of mixing console to blend the various microphones onstage into two left and right channels for output to the main speakers. A direct signal from the stage or main concert mixing board produces the cleanest recording without crowd noises and unwanted room reflections.
Connect one of the extra left and right output channels directly into your portable DAT machine. Check ahead of time that you have the proper adapter cables to connect your DAT to the mixing board outputs. Whenever possible, you should use XLR three-prong cables to connect to the back of the mixing board. If your portable DAT machine does not have XLR inputs, you will need an XLR-to-quarter-inch or stereo mini-cable adapter. (See Appendix A, "Creating the Ultimate Web Sound Studio: Buyers Guide and Web Resources" for more on XLR and adapters.)
If you are at an event or concert without a PA system or you do not have access to the main mixing console, use a microphone plugged into a portable DAT to capture the sound source. Set up a six- to eight-foot tall microphone stand toward the middle or back of the concert hall at the center stage position. Attach two small diaphragm condenser microphones to the top of the stand and point them toward the stage. You can place the microphones in an "x" position, as shown in Figure 3-10, or parallel to each other and six feet apart, pointed slightly outward to the left and right sides of the stage, as shown in Figure 3-11.
Figure 3-10. Microphones placed in an x crossing position
Figure 3-11. Microphones placed in parallel, pointing slightly outward
18.104.22.168. On-location interviews and panel discussions
In-studio interviews are not always possible and, in some cases, not even preferred. Even if the acoustics and equipment selection are less than optimal, it is best to interview people in an environment in which they're comfortable. An on-location interview can be captured easily with a small portable DAT machine and a microphone. Set up your equipment efficiently and try to make the recording experience as transparent as possible. Often people are intimidated by speaking into a microphone or are uncomfortable just knowing every word is being captured on tape.
Depending on the level of extraneous noise in your immediate environment and the number of voices you are capturing, use one of these techniques to record interviews:
22.214.171.124. Capturing ambient sounds
To record ambient environmental sounds such as a city street with cars passing or a distant bird call in a forest, use an omnidirectional microphone with a wind protective foam covering (known as a windsock). A shotgun microphone works best for capturing the direct signal of a distant sound source.
The greatest challenge to ambient recording is capturing soft or distant sounds without increasing the level of system noise. Using high-quality, professional gear is the best way to ensure good ambient recording. If you are capturing the soft sounds of a distant bird call, for example, and use a consumer-grade portable DAT machine, you will instantly notice the presence of system noise in the form of a continuous "shhh." This is because boosting the input levels increases the system noise. Professional-grade DAT machines have higher quality mic pre-amps and do a better job of boosting the signal without introducing noise.
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