寻求改进教育视频? 首先改善音频

在7 / 8月刊中，我建议返校购物清单对于刚开始视频制作的老师. 因为有优秀的免费工具可用, my advice was to get to work using them and to spend your money only after you discover where your resourcefulness begins to fail. In this case, premature optimization is the root of all overspending.

Students tend to be generously tolerant of many shortcomings in otherwise-helpful instructional video, 但不是音频问题. 因此, it is likely that improving the audio quality is where teachers will first be looking to spend their money. While educational video is a small niche for the recording industry, our needs intersect with other market segments that collectively create adequate demand for a wide variety of recording tools.

提高音频质量最好在前期制作中完成, either by making the environment quieter or by improving the fidelity of the audio signal being recorded. Fixing audio beyond normalization in postproduction is always destructive. You can never add quality speech signal; you can only remove some amount of undesirable noise without noticeably damaging what quality speech signal was captured.

The traditional audio recording setup involves a microphone supplying a mic-level signal to a pre-amp, where the signal is substantially amplified to line-level while introducing minimal noise. The pre-amp additionally provides power to condenser microphones. This line-level signal can be captured by the input on your computer’s audio card to produce a discrete analog of the signal as a sequence of samples. Noise can be introduced at any of these points or in cables between them. 在几乎所有的情况下, I’d recommend minimizing the points of failure by using a quality, 一体化USB麦克风.

买麦克风的时候, there are two critical specifications to look for: the frequency response and the polar pattern.

The frequency response is usually reported as either a range of frequencies that the microphone will capture or as a graph showing the sensitivity at different frequencies. Inexpensive microphones intended for telephony are designed to carry signals over the limited channel—typically only recording down to 100 Hz—that telephone lines handle, 你应该避免它们. Unless you have a very-high-pitched speaking voice, that won’t work well. The human ear can hear sound at frequencies from around 20 Hz to 16,000 Hz; the lowest pitch notes demanded of professional opera singers are above 70 Hz (73.4162 Hz to be exact), so that’s a safe low range for instructional speech sounds.

The polar pattern describes the microphone’s sensitivity depending on the location of the sound source around the microphone. 记录你自己, 你应该选择心脏型, which means that it records what it’s aimed at very well and it depresses the ambient noise from all other directions. Some microphones that are popular with educators use a bidirectional polar pattern, which is great for interviewing a guest from directly across a desk.

There are three general microphone form factors that make sense for teachers: stand mics, 耳机麦克风, 还有lavilier麦克风. 从历史上看, 我建议你要么戴耳机，要么戴护目镜, since incorrect mic placement is a common problem that can be avoided by using microphones attached to your body close to your mouth. I felt that tabletop stand microphones would get in the way of the camera and the teacher would vary their distance from the microphone too much, 导致录制水平不均匀. I’ve since come around on this: A well-placed stand microphone tends to keep teachers from fidgeting away from the microphone and around the frame.

如果你真的想花超过60美元来改善你的音频, 一个潜在的有用百家乐软件是你当地的吉他店. 在那里工作的每个人都必须教吉他课, 所以他们很可能会同情同事. Many guitar stores have rental mics that they may let you try out to help decide which one works best for your voice.

[本文发表于2018年9月号。 流媒体杂志 “声音很好。."]