Main Lecture Content:

Music Tech Student “What to Know About Sound” Page

Quiz Questions:

1. If you could see the particles in a single sound compression in slow motion, describe what it would look like. What would they be doing prior to their first reflection?

2. Why do you sometimes hear a sound noticeably after you see the performer create it?

3. An F#4 has a frequency of 370 Hz, what frequency is two octaves higher? What frequency is 2 octaves lower?

4. What did Michael Faraday figure out that forms the backbone of audio recording and reproduction?

5. In the context of analog-to-digital conversion, what is sampling?

6. Based on what you’ve learned so far, why do you think speaker cabinets often contain speakers (diaphragms) of varying sizes?

Download more questions and essay prompts for free at the MTS.org TPT store.

Besides the activity below, check out our chladni plate and laser visualizer project here.

Activity: Analyze the Frequency Spectrum

Set up: Select a bunch of songs that represent different types of music and show them to the class using a spectrum analyzer. If you have a parametric EQ in your DAW with an FFT overlay, that works very well. Otherwise, you can use a free tool like this one by Google (shown below).

“Royals,” as shown in Google’s tool. You can clearly see the low frequency bass, the vocal, and the percussive highs.

The first example I showed was a karaoke track I had made for “Unsteady,” by X Ambassadors. I showed how the track was made with a large space in the mids carved out for the vocalist. I then un-muted an a Cappella I had downloaded and they instantly saw how the full spectrum was complete and could hear how clean the vocal was with nothing competing with it.

From there, you can take it in whatever direction you want. Some examples: “Royals,” by Lorde shows a simple mix that has low, mid and high content with plenty of space between elements (bass on the bottom, voice in the middle, percussion on top). An a Cappella song will show nothing down super low, since the voice doesn’t produce frequencies down there; “Down in the River to Pray,” from Oh Brother, Where Art Thou, shows the lead vocal not competing with anything at the beginning, and much more covered up later on by similar frequencies (skip from the first verse to later on, back to back). Anything from Star Wars shows a carefully-crafted classical music spectrum, with overall levels going up and down appropriately, and soloists creating lovely fundamental and harmonic patterns that rise a little above everything else. “Rain Dance,” by Karl Jenkins is a good example of a thin and incomplete spectrum that is completed later when more instruments are added; there’s also a flute near the end that sticks out a little too much on some speakers, which is clearly seen on the analyzer.

Spectrum analyzer showing a trumpet solo in Star Wars jutting out from the mix

Spectrum analyzer showing a trumpet soli in Star Wars jutting out above the orchestra. The pattern of a fundamental and upper harmonics is clear, as is a low cut at the bottom of the spectrum.

When I did this exercise, I showed about seven songs that were completely different. It gave the students a new way to consider music and a great view of what the big picture is when producing a song. This provided a foundation for every discussion hereafter, especially equalization and arranging. If you find it useful, consider showing the students a chart that shows the frequency range of common instruments and show where they all sound while listening to each song. Talk about the importance of a good arrangement—if you choose instruments that sound in different areas of the spectrum, mixing is that much easier; if you leave out a part of music (bass, melody, harmony, rhythm) or don’t have every spectral band represented, the song won’t sound complete.

After we did this in class, I assigned the students an online discussion where they essentially repeated the exercise with their own music and shared it with the class asynchronously.

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