Q1.
Increase the frequency in steps of 100 Hz up to 1000 Hz and describe how the sound changes.
Answer
As the frequency rises from 100 Hz to 1000 Hz, the sound becomes steadily shriller — the pitch goes up — even though the volume setting has not been touched.
| Frequency set | How it sounds | Wavelength in air (v = 344 m s⁻¹) |
|---|---|---|
| 100 Hz | Deep, humming, like a distant engine | 344 ÷ 100 = 3.44 m |
| 300 Hz | Full, like a low male voice | 344 ÷ 300 = 1.15 m |
| 600 Hz | Bright, clear | 344 ÷ 600 = 0.57 m |
| 1000 Hz | Thin, piercing, whistle-like | 344 ÷ 1000 = 0.34 m |
Why the pitch rises: pitch is how our brain interprets frequency. A higher frequency means the density of the air at your eardrum swings from maximum to minimum and back more times each second, and the ear reads that as a shriller sound. In general high pitch goes with high frequency and low pitch with low frequency, although the exact relation is not a simple one. Note that the speed of sound stays 344 m s⁻¹ throughout — it is the wavelength that shrinks, since λ = v/ν.
Tip: loudness may seem to change a little as you sweep the frequency. That is not the app — the human ear is naturally most sensitive around 1000 – 4000 Hz, so equal-energy sounds do not seem equally loud.