This is episode is going to be a little different than others I have written; I want to narrow my focus onto the more technical aspects of sound by covering some terminology.
Frequency, Hertz, 12 Tone Equal Temperament
Frequency is the amount of waves that pass through a certain area in a given amount of time; essentially it’s the frequency of vibrations that occur. This is what gives a note its pitch; a high frequency corresponds to a high pitch; a low the frequency corresponds to a low pitch. Frequency, pitch, and vibration are interlocked.
Hertz, is a specific way of measuring frequency; it represents the amount of waves that pass through per second. And, you may have heard of A440 tuning before; this is the tuning that western music is based off of; the note A above middle C is tuned to 440 Hertz; 440 vibrations within a second! This standardization; A440 tuning, plus the division of the octave into 12 equal parts - where each half step is the same distance away as any other half step- is what ensures that music will sound the same even in varying regions. Before this was standardized, region to region the sound (or specific pitch) of notes could vary.
12 tone equal temperaments creation is owed to a gentleman named Zhu Zaiyu (朱載堉), who worked to discover 12 tone equal temperament through specific calculations: “by dividing the length of string and pipe successively by 12√2 ≈ 1.059463, and for pipe length by 24√2,[10] such that after twelve divisions (an octave) the length was divided by a factor of 2”.
Compression and Equalization
Compression is a tool that is used to level the output decibels (db) of certain frequencies. For example, if I were recording guitar I might use compression because not all of the strings on the guitar produce the same volume; the lower string notes -their frequencies- may drown out the higher string notes, and it might be necessary to even out the sound. Essentially, ‘compression reduces the dynamic range’ of the input signal, by increasing the volume of the quieter frequencies and lowering the volume of the louder frequencies. There are a few parameters available on a compression tool within a DAW (digital audio workstation). First off, we have threshold, this is the input level (measured by decibels) where the compression will begin. It follows that a threshold set to a certain decibel level will have more or less of an impact on the sound; threshold set to a lower db will compress more of the quieter elements of the sound; threshold set to higher db will compress the more louder elements of the sound. Also present within compression is output gain, this is simply the amount of gain that is added to the signal after compression. (Learn about the difference between gain and volume here.)
Equalization and compression share some core similarities but have a key difference. While compression deals with the output gain and reducing the dynamic range, equalization is the manipulation of the frequencies present in the recorded signal, there is more choice as to what frequencies will be boosted or reduced. In Ableton, and other DAWs there is a visual representation of the frequencies (figure 1) on an EQ graph.
Lets now look at how to interpret a graph of equalization.
We can view figure 1 as a graph with an x and y axis. The x or horizontal axis displays the different frequencies, which are measured in kilohertz (a measure of frequency equivalent to 1,000 cycles per second), below 100khz to past 10khz. The y axis, or vertical aspect, measures the presence of certain frequencies. And, we see that there are certain peaks and valleys within the graph; those peaks and valleys are representative of the presence of certain frequencies.
Within the EQ tool, we see some more parameters. On the left side, there a frequency, gain, and Q nob. We’ve already covered frequency, as that nob just will shift the nodule on the graph amongst the frequencies. The gain nob can boost or reduce certain frequencies; raising or lowering the nodule on the graph. For example, if I were to reduce the gain of the 10khz frequency, this would reduce the higher frequencies or the signal, just as, increasing the gain on frequencies below 100htz would increase the bass of the signal.
Q is a little more complicated. This is the relationship between the center frequency and the overall bandwidth; raising the center point frequency (this is what is called Q) narrows the bandwidth, lowering the Q expands the bandwidth. I imagine Q as raising or lowering a blanket from the center; the higher you raise the blanket the shorter the distance (bandwidth) becomes from side to side, just as lowering the blanket would increase the side to side distance. Q is a helpful tool for isolating specific frequencies, this article explains it very well.
Equalization is an incredibly useful tool in the mixing process; having the ability to boost or remove certain frequencies is essential to the recording process.
Resonances, and Fundamental and Overtone Frequencies
Fundamental and overtone frequencies all relate back to resonance. A fundamental frequency is the lowest frequency produced by a given instrument, on an EQ graph this would be displayed as the frequency that is furthest to the left; the lowest hertz. But there’s more to sound than its fundamental frequency, over top, or above that fundamental frequency we find overtones; these are frequencies higher than the fundamental.
**Side note: Overtones and overdrive are both related; overdrive (or distortion) is an effect that boosts or amplifies other frequencies (overtones) present in the signal to produce a dirty sound.
Resonances are essentially just the combination of the fundamental frequency and overtones. Specific types of overtones are either sympathetic or unsympathetic to the fundamental; sympathetic overtones are called harmonic resonances. Harmonic resonances are frequencies that form ‘integral multiples’ overtop the fundamental frequency. For example, if one were playing an A note plus an E note on the violin, this would cause the strings to vibrate and produce certain harmonic overtones. Together, because they share a harmonic overtone (or integral multiple), 1320htz is a resonant frequency produced.
Click here to learn more about acoustic resonance.
Conclusion
Before I learned what all this stuff meant, I would just play around in Ableton (turning nobs, playing with automation etc.) until I found something that sounded good. All that has really changed after learning about the various terminologies of sound and how they work together, is that now, I have more control over what I would like to hear and it takes less time to get there.
I’ve previously noted that the best way to learn is to explore and discover what works for yourself, and this still applies. The technical knowledge should always act as a supplementary force to your creative drive.
Also this past week, I did a collaboration track with Ghostwrite; ‘In Your Head’ is out now, you can listen here.
Hopefully you enjoyed learning about these elements of sound as much as I have.
See you all next week.
About the Author
Isaiah Grip is a 21 year old multi-instrumentalist composer (guitar, piano, violin, and voice) out of Longmont, Colorado who records and studies music independently under the name Tetra Veda, as well as collaborating with Ghostwrite Inc, and playing guitar in the progressive metal band Cloud Temple. His personal repertoire can be found on Bandcamp and YouTube under the name Tetra Veda.
When I taught at a college in AZ, I had to fire our sound engineer. He was very lazy about EQ which meant my jazz choir would work on a show for 6 weeks and see it destroyed by his malfeasance. One of his worst mistakes was to EQ through his headphones instead of EQ through the house. We would sound great in his stereo headset but lousy in house. So your article is well appreciated. Same goes with compression. I do audio recordings of my voice students using a small sound board which does not have compression. My next purchase will be a soundboard with compression!
This has been an education for me, I appreciate it. Its amazing how much we take for granted and how the ear has an instictive way of knowing what sounds right.