Smartphone microphone and sound experiments
23 classroom-tested activities with the free FizziQ app, for high school, middle and high school, middle school, elementary.
The microphone turns the phone into a sound level meter, a frequency meter, an oscilloscope and a spectrum analyzer. Combined with the tone generator, it covers most of the acoustics syllabus. Instruments in FizziQ: sound level meter (dB), frequency meter, spectrum analyzer (FFT), spectrogram, oscilloscope, acoustic stopwatch, tone generator. Read the glossary entry on the microphone.
Each activity below has a protocol, expected results, scientific background, a printable PDF handout and a QR code that opens it directly in the app. FizziQ is free on iOS and Android, needs no account, and shows no advertising.
Activities
- Destructive sound interference High school 45 min
Two smartphones emit a 680 Hz tone while a third maps zones of silence and reinforcement with the FizziQ sound meter, explaining active noise cancellation.
- Acoustic beats at 440/441 Hz High school 35 min
The FizziQ synthesizer plays 440 and 441 Hz tones on a smartphone; students record the pulsing sound level and verify the beat frequency equals the difference.
- Adding sound levels in decibels Middle and high school 30 min
Using three smartphones and the FizziQ sound meter, students measure the level of two 60 dB white-noise sources played together and find a 3 dB rise, not a doubling.
- Coefficient of restitution High school 25 min
By recording bounce sounds with the smartphone microphone in FizziQ, students time the intervals between impacts and calculate a ball's coefficient of restitution.
- Sound level and distance High school 35 min
Two smartphones run FizziQ: one emits white noise while the other measures decibels at increasing distances, letting students test the inverse square law for sound.
- Doppler effect of a vehicle High school 35 min
The frequency shift of a passing vehicle is analyzed with FizziQ's smartphone spectrum analyzer; students apply the Doppler formula to calculate its speed.
- Speed of sound: a test tube High school 35 min
Blowing across a water-filled test tube excites resonance; the FizziQ spectrum analyzer on a smartphone measures each frequency to compute the speed of sound.
- Pendulum period: isochronism Middle and high school 35 min
Timing ten oscillations at several amplitudes, students test Galileo's isochronism with FizziQ on smartphone or tablet and compare readings with T = 2π√(L/g).
- Reaction time by stopwatch Middle school 30 min
Two hand claps, two stopwatches: the manual timing minus FizziQ's microphone-triggered stopwatch gives a student's reaction time. Middle school, on smartphone.
- Doppler effect: sound pendulum High school 40 min
A tone from a swinging smartphone shifts in pitch; students follow it with FizziQ's frequency meter and derive the pendulum's maximum speed from the Doppler shift.
- Speed of sound: two stopwatches High school 30 min
Two smartphones running FizziQ's acoustic stopwatch are triggered by the same claps; the delay over a known distance gives students the speed of sound directly.
- Cardiac auscultation by mic Middle school 25 min
Pressed against the chest, a smartphone microphone picks up heart sounds; FizziQ's low-pass filter isolates them so middle school students read their heart rate.
- Shepard auditory illusion High school 30 min
High school students decode the Shepard tone with FizziQ's spectrum analyzer and frequency meter on a smartphone, revealing octave-spaced sinusoids behind the rise.
- Chromatic scale and frequencies Middle school 30 min
Using the FizziQ frequency meter on a smartphone or tablet, middle school students measure the twelve chromatic notes and show their geometric progression.
- Helmholtz resonance: a bottle High school 30 min
The pop of an uncorked bottle reveals Helmholtz resonance: students measure its frequency with the FizziQ smartphone app and derive the speed of sound. High school.
- Harmonic and inharmonic sounds Middle school 30 min
Compare bell and oboe spectra with FizziQ's spectrum analyzer on smartphone or tablet: oboe overtones are integer multiples, bell overtones are not. Middle school.
- Timbre and harmonics Middle school 30 min
Why do a flute, guitar and piano sound different on one note? Students compare spectra with FizziQ's analyzer on smartphone or tablet and link timbre to harmonics.
- Speed of sound: tube resonance High school 30 min
One smartphone sends white noise into a tube while a second runs the FizziQ spectrum analyzer; the resonance peaks yield the speed of sound. High school physics.
- Tuning forks: pitch of A Middle school 30 min
Three historical tuning fork recordings analyzed with the FizziQ frequency meter, spectrum and oscillogram trace how the pitch of A became 440 Hz. Middle school.
- Spectrum of sung vowels Middle school 30 min
Sing vowels into the FizziQ spectrum analyzer and compare their harmonic peaks: formants show how mouth cavities filter the voice. Smartphone app, middle school.
- White noise: spectral content Middle school 25 min
Students listen to white noise, then analyse it with FizziQ's smartphone spectrum analyzer: a flat FFT spectrum shows equal intensity at every audible frequency.
- Spectrogram of bird song High school 30-45 min
A nightingale recording analysed in the online FizziQ Web spectrogram: students read frequencies and sequence timing, then compare species by spectral signature.
- Air columns and pitch Elementary 45-60 min
Blowing into water-filled tubes, primary pupils change the pitch, identify notes with the FizziQ Junior note recognizer on tablet and link tube length to frequency.
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