Join Brian Lee White for an in-depth discussion in this video Measuring frequency, part of Foundations of Audio: EQ and Filters.
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Frequency, or the speed at which a soundwave oscillates back and forth, is measured in cycles per second, or hertz for short. In a graph charting amplitude Y, over time X, frequency is the rate of change in amplitude, or how many times the waveform cycles up and down per second. A 100 Hz tone pushes and pulls a speaker cone 100 times per second, while a 1 kHz tone would push and pull that same speaker cone 1,000 times per second.
As frequency increases, so does the perceived pitch of the soundwave. It's generally accepted that humans can perceive sounds from about 20 Hz to 20,000 Hz, or 20 to 20. Although sounds under 100 Hz are felt more than they are heard as the low-frequency vibrations resonate in our chest, more so than in eardrums. Likewise, our acuity for hearing higher-frequency sounds diminishes with age. As we grow older, or prematurely damage our hearing from over-exposure to loud environments, our ability to hear high frequencies can be severely reduced, sometimes to well under 10,000 Hz and lower, effectively cutting in half are 20 to 20.
This is why it is important to protect your hearing in loud environments, as your ability to perceive a wide range of frequencies will ultimately help you learn and use equalization better. But while frequency determines the pitch of a soundwave, that's only half the story. Amplitude. or the amount of energy in a soundwave's frequency oscillations, determines its perceived loudness, which we'll discuss in the next movie.
- Measuring frequency and amplitude
- Understanding the relationship between frequency and pitch
- Working with EQ controls such as bandwidth (Q) and gain
- Using graphic EQ
- Understanding the shelving and high-pass and low-pass filters
- Creating focus with EQ
- Creating complementary EQ curves
- Performing frequency bracketing with filters
- Automating EQ
- Using frequency analyzers
- Using harmonic generators to excite frequency content