Chapter 1 Quiz

Closed book, honest effort, no shame in misses — every wrong answer here is cheaper than the same confusion in a session. Score yourself with the table at the end.

Multiple Choice

1. Physically, sound traveling across a room is best described as: A) air molecules flying from the speaker to your ear B) a pattern of pressure changes passing through the air C) electrical energy radiating through space D) vibrations that only exist once they reach an eardrum

Answer **B.** Sound is a traveling pattern of compressions and rarefactions; the molecules themselves barely move, like stadium-wave fans who never leave their seats. A is the classic misconception — molecules shove neighbors and return. C describes the signal *inside your cables*, not the air. D confuses the physical event with perception; the pressure wave exists whether or not an ear catches it.

2. Frequency is measured in: A) decibels (dB) B) hertz (Hz) — pressure cycles per second C) meters per second D) LUFS

Answer **B.** One hertz is one complete cycle per second. A (decibels) measures level/amplitude relationships. C is the *speed* sound travels through a medium, which is constant across frequencies. D is a loudness unit you'll meet properly in [Chapter 33](../../part-07-mastering/chapter-33-loudness-wars-streaming/index.md) — not a frequency unit.

3. A note at 220 Hz moves up one octave. Its new frequency is: A) 240 Hz B) 330 Hz C) 440 Hz D) 2,200 Hz

Answer **C.** An octave is a doubling: 220 × 2 = 440 Hz. A treats an octave as a fixed +20 Hz step — the ear hears ratios, not differences. B is ×1.5 (a musical fifth — the 3rd-harmonic relationship). D is ×10, roughly three-and-a-third octaves.

4. The textbook range of human hearing is approximately: A) 20 Hz–20 kHz B) 200 Hz–2 kHz C) 20 Hz–200 kHz D) 2 Hz–20 kHz

Answer **A.** Twenty to twenty thousand hertz, about ten octaves — with the honest footnote that adult ceilings commonly sit lower (15–17 kHz). B spans barely the midrange — telephone-ish territory. C's top is dog-whistle-and-beyond fantasy. D's bottom is below anything heard as tone; below ~20 Hz you feel throb, not pitch.

5. "dB SPL" specifically means a decibel value referenced to: A) the loudest sound a system can produce B) your DAW's maximum meter level C) the threshold of human hearing (20 micropascals) D) the average level of a pop record

Answer **C.** dB SPL measures acoustic pressure against the quietest sound a healthy young ear can detect — so 0 dB SPL is "barely audible," not "silence." A and B describe ceiling-referenced scales (your DAW's flavor is [Chapter 2](../chapter-02-digital-audio/index.md)'s story — and confusing it with SPL causes real pain). D is not a standard reference for anything, despite how some masters behave.

6. By the common psychoacoustic rule of thumb, a +10 dB increase is perceived as roughly: A) ten times as loud B) twice as loud C) barely noticeable D) the same loudness, higher pitch

Answer **B.** "+10 dB ≈ twice as loud" is the working approximation — while the underlying pressure has more than tripled. A confuses perception with the physical ratio (+20 dB is ten times the *pressure*, still nowhere near "ten times as loud"). C undersells it badly — +10 dB is a dramatic jump. D confuses amplitude with frequency; level changes don't change pitch.

7. A sine wave is unique among waveforms because it: A) contains every harmonic at equal strength B) contains only odd harmonics C) contains a single frequency and nothing else D) cannot be reproduced by digital systems

Answer **C.** The sine is the atom: one frequency, no harmonics — which is exactly why a sine sub vanishes completely on speakers that can't reproduce its fundamental. A describes no standard waveform (a saw has all harmonics, but *decreasing* in strength). B describes the square/triangle family. D is false — digital systems reproduce sines superbly ([Chapter 2](../chapter-02-digital-audio/index.md)).

8. The waveform with ALL harmonics present — the bright, full workhorse of synthesis — is the: A) sine B) triangle C) square D) sawtooth

Answer **D.** The saw carries the complete harmonic ladder, which is why it sounds rich and why it's the raw material for synth strings, brass, and the pads under half of modern pop. A has no harmonics at all. B and C carry odd harmonics only — the triangle's weak (soft, rounded), the square's strong (hollow, buzzy).

9. Timbre — why a piano and a trumpet on the same note sound different — is primarily determined by: A) the fundamental frequency B) the recipe of harmonics and how the sound evolves over time C) the loudness of the performance D) the key of the song

Answer **B.** Identity lives in the harmonic recipe (which multiples, at what strengths) plus the envelope — transient included. A is what's *shared* in the comparison: same note, same fundamental. C changes intensity, not identity (mostly). D is a property of the composition, not of a single sound's character.

10. The harmonics of a 100 Hz fundamental fall at: A) 100, 200, 300, 400 Hz... B) 100, 150, 200, 250 Hz... C) 100, 1,000, 10,000 Hz... D) random frequencies that depend on the instrument

Answer **A.** Harmonics sit at whole-number multiples: 1×, 2×, 3×, 4×... B uses +50 Hz steps — additive, not multiplicative, and not the physics. C uses ×10 steps. D confuses *which harmonics are strong* (instrument-dependent — that's the timbre recipe) with *where they fall* (fixed by the fundamental).

11. A transient is: A) the steady, held portion of a note B) the short burst of broadband energy at a sound's onset C) any sound below 100 Hz D) the echo that follows a sound in a room

Answer **B.** First milliseconds, energy sprayed across the spectrum, carrying identity, punch, and rhythmic placement. A is the sustain — the opposite region. C describes a frequency range, unrelated. D describes reflections/reverberation — space, not onset (that story starts in [Chapter 24](../../part-05-mixing-foundations/chapter-24-reverb-delay/index.md)).

12. Chop the first 50 ms off a recorded piano note and listeners struggle to name the instrument. This demonstrates that: A) pianos have no harmonics B) much of a sound's identity is carried by its transient C) the fundamental frequency was deleted D) human ears can't hear sounds shorter than 50 ms

Answer **B.** The attack is an identity card; remove it and the sustain reads as organ-ish ambiguity. A is false and unrelated. C is wrong — the fundamental persists throughout the sustain; only the onset was removed. D is false (and backwards — ears resolve far shorter events; that acuity is *why* transients matter).

13. All frequencies travel through air at the same speed. Musically, this matters because: A) it makes bass louder outdoors B) a chord or drum hit arrives at your ear with its low and high parts still together C) it allows sound to travel through a vacuum D) it makes all rooms sound identical

Answer **B.** If speed varied with pitch, music would smear apart over distance — different seats would hear different alignments. A confuses speed with level. C is false; sound needs a medium at any speed. D is very false — rooms differ wildly in how they *reflect and absorb* frequencies (Part II's whole drama), which is separate from travel speed.

14. The structure in your inner ear that sorts sound by frequency along a physical map is the: A) eardrum B) ear canal C) cochlea D) jaw joint

Answer **C.** Different frequencies excite different spots along the cochlea's basilar membrane — a biological spectrum analyzer reporting frequency-sorted levels to the brain. A is the input diaphragm (pressure → motion), no frequency sorting. B is plumbing — a funnel. D is anatomy's bystander here.

15. A nearly pure sine 808 at 40 Hz sounds huge on bass-hyped headphones but disappears entirely on a phone speaker because: A) phones convert all audio to mono B) the phone can't reproduce 40 Hz, and a sine has no harmonics for the brain to infer the pitch from C) sine waves can't be stored in compressed files D) 40 Hz is above the phone's range

Answer **B.** Two facts stacked: the driver physically can't produce the fundamental, and a sine offers nothing *above* the fundamental — no harmonic ladder, so no missing-fundamental inference, so silence. A is irrelevant to the symptom (mono summing matters elsewhere — [Chapter 25](../../part-05-mixing-foundations/chapter-25-panning-stereo-field/index.md)). C is false. D is upside down: 40 Hz is far *below* the phone's floor.

True/False — with Justification

Answer true or false, then justify in one or two sentences. The justification is where the points live.

16. Doubling the sound pressure of a signal makes it sound twice as loud.

Answer **False.** Doubling pressure is only +6 dB; the common rule of thumb says you need around +10 dB — more than triple the pressure — before listeners report "twice as loud." Perception is logarithmic; it compresses big physical changes into modest loudness changes.

17. A 100 Hz wave in air is physically longer than a 1 kHz wave.

Answer **True.** Wavelength = speed ÷ frequency: ~343 ÷ 100 ≈ 3.4 m, versus ~34 cm at 1 kHz. That ten-to-one size difference is why low frequencies pass through walls and around obstacles while highs beam straight and die in soft material.

18. Two notes an octave apart have frequencies in a 2:1 ratio.

Answer **True.** The octave *is* the doubling — 110 to 220 Hz, 220 to 440 Hz. Equal musical intervals are equal ratios, which is also why analyzers display frequency logarithmically.

19. The sustain of a note carries most of its rhythmic placement — your sense of where the beat is.

Answer **False.** Rhythm locks onto *transients* — the attack moments. That's why pads and swells feel grid-less and why a mix with shaved-off transients loses its sense of punch and timing.

20. Hearing damaged by sustained loud exposure typically heals within a few weeks.

Answer **False.** The cochlea's hair cells do not regenerate in humans; noise-induced damage is permanent (temporary muffling after one loud night is your system recalibrating — repeat the dose often enough and the loss stops being temporary). This is the physiological reason the book treats your ears as the one un-upgradeable component.

Short Answer

21. Explain, in two or three sentences, why the decibel scale is logarithmic rather than linear — and name one practical consequence for a producer.

Answer The span between barely-audible and painful covers around a million-to-one in sound pressure; a linear scale would need unusable numbers, and the ear itself perceives ratios, not raw differences. Logarithmic decibels match perception: equal dB steps sound like equal loudness steps. Practical consequence (any one): small dB moves are bigger than they look (+6 dB is double the pressure); level judgments must respect that a "little" boost is physically large; loudness comparisons need matched conditions because the scale compresses huge differences into small numbers.

22. A hi-hat and a kick drum hit at the same moment, at the same measured level. Describe each in frequency and envelope terms — at least two specific contrasts.

Answer Frequency: the kick concentrates its energy low — fundamental commonly in the tens-of-Hz region with body around 60–100 Hz — while the hat lives almost entirely high, with its energy above roughly 3 kHz and lots of sizzle in the 6–12 kHz region. Envelope: both are transient-led, but the kick's transient hands off to a pitched, resonant body and tail, while the hat is essentially *all* noise-like transient and short metallic decay with no pitched sustain. (Bonus contrast: the kick survives walls and trunks; the hat gets absorbed — wavelength physics.)

23. Why does a square wave sound "hollow" while a sawtooth sounds "full"? Answer in harmonic-recipe terms.

Answer The square contains only the odd-numbered harmonics (1st, 3rd, 5th...), strongly present — that missing even-harmonic family leaves a hole in the recipe the ear reads as hollowness or woodiness. The saw contains *every* harmonic, odd and even, in a smoothly decreasing ladder — a complete recipe the ear reads as full, bright, and brassy. Same fundamental, different ingredient lists, different identities.

24. Your collaborator says their rough mix sounds "muddy and kind of harsh at the same time." Translate both complaints into frequency-range hypotheses, and state what you'd look at first on a spectrum analyzer.

Answer "Muddy" points at an energy pileup in roughly the 200–400 Hz region — typically several sources (vocal warmth, guitar body, kick ring, pad low end) stacking in the same zone. "Harsh" points at excess in roughly 2–6 kHz, where the ear is most sensitive — overcooked presence, edgy cymbals, or piled-up upper-mid energy. On the analyzer: check whether there's a persistent mountain in the low-mids and a hot shelf or spikes in the 2–6 kHz region, then identify *which instruments* feed each (the analyzer confirms; ears and muting locate). The fixes are [Chapter 22](../../part-05-mixing-foundations/chapter-22-eq/index.md)'s business — the diagnosis is already yours.

Applied Scenario

25. The bedroom-to-Bluetooth disaster. Your friend Maya produces a synth-pop demo on bass-heavy consumer headphones in late-night sessions. On her headphones: perfect. On her portable Bluetooth speaker: the bass line is missing in action, the lead vocal sample sounds trapped in a shoebox, and the shaker loop is so bright her roommate left the room. Using only Chapter 1 knowledge: (a) give a frequency-vocabulary hypothesis for each of the three failures, (b) explain what role her headphones and her late-night listening each played, and (c) propose three zero-dollar actions she should take before touching any plugin.

Answer **(a)** Bass MIA: her bass line probably lives almost entirely in low fundamentals (sub region, sine-ish recipe) below the small speaker's reproduction floor, with too few harmonics in the 100–300 Hz region to carry the line when the floor cuts off the foundation. Shoebox vocal: excess energy in the roughly 300–800 Hz "boxy" zone — likely the sample's inherent character plus other parts stacking in the same region — which her headphones' hyped lows disguised as warmth. Burning shaker: excess energy in the high regions (roughly 6–12 kHz) — she pushed it while monitoring on a system, and at a time of night, that under-reported the top end. **(b)** The headphones are bass-hyped and likely soft up top: they flattered her sub (so she never added audible harmonics), masked the low-mid pileup (so the boxiness read as body), and under-played the highs (so she overcooked the shaker to compensate). Late-night quiet listening compounds the top-and-bottom misjudgment — at low volumes the ear under-reports the spectrum's extremes (Part I's listening chapter maps this formally), and tired ears' high-frequency judgment drifts. **(c)** Zero-dollar actions: (1) run the test-tone floor audit on both systems — learn exactly where the Bluetooth speaker's bass cliff is, and where the headphones flatter; (2) start every session by playing two or three professional reference tracks in her genre on the same headphones at the same level, and A/B her demo against them — calibrating her ears to the system using records she trusts; (3) adopt the three-systems ritual before calling anything done — headphones, Bluetooth, phone — journaling each failure in frequency terms so the fixes (coming in Parts V–VI) have addresses. Bonus credit for: moderate, consistent monitoring volume, and not mixing exhausted at 2 a.m.

Scoring

Count one point per fully correct answer (justifications and explanations required where asked — generous partial credit for partially right reasoning). 25 points possible.

Score Verdict Prescription
Below 50% (<13) The alphabet hasn't stuck yet Re-read the science core slowly, redo exercises A1–A5 and C1–C2, then retake. No shame — this chapter is dense and everything later depends on it.
50–70% (13–17) Concepts present, connections loose Review the sections behind your misses (most people: harmonics and dB), do Listening Lab B1–B3, retake the missed questions in a day or two.
70–85% (18–21) Solid working grasp Skim your weak spots, make sure the journal habit is alive, and move to Chapter 2 with confidence.
Above 85% (22–25) Fluent — the vocabulary is yours Go straight on. Consider Part D of the exercises if you skipped it; you're ready for the deep end.