EEEN 462 - Audio Frequency Laboratory Exercise

Generate, analyze, and understand sine waves at different frequencies

Laboratory Objectives

Laboratory Procedure

  1. Click the "Initialize Audio" button to enable audio generation (required by browsers)
  2. Select a frequency from the buttons (100Hz to 10kHz) to generate a sine wave
  3. Click "Play Tone" to hear the selected frequency through your speakers/headphones
  4. Observe the time-domain waveform and frequency spectrum visualization
  5. Use "Frequency Sweep" to hear a progression through all frequencies
  6. Complete the post-lab quiz to test your understanding

Frequency Controls

Status: Audio system not initialized. Click "Initialize Audio" to begin.

Select Frequency (Hz)

Current Signal Information

Selected Frequency: None Hz

Period: - seconds

Wavelength (in air): - meters

Note: Wavelength calculated at speed of sound (343 m/s at 20°C)

Signal Visualization

Time-domain representation (2 cycles shown)

Frequency Spectrum (FFT magnitude)

Human Hearing Context

Human Hearing Range: 20 Hz to 20,000 Hz (typical young adult)

Selected Frequency Range: 100 Hz (bass) to 10,000 Hz (treble)

Musical Context: 440 Hz is concert A (A4), 1000 Hz is between B5 and C6

Post-Lab Quiz

1. Which frequency has the shortest period?

a) 100 Hz
b) 1000 Hz
c) 5000 Hz
d) 10000 Hz
Answer: d) 10000 Hz. Period = 1/frequency, so higher frequencies have shorter periods.

2. What is the wavelength of a 1000 Hz tone in air at 20°C (speed of sound = 343 m/s)?

a) 0.343 m
b) 3.43 m
c) 34.3 m
d) 343 m
Answer: a) 0.343 m. Wavelength = speed of sound / frequency = 343 / 1000 = 0.343 m.

3. In the frequency spectrum display, a pure sine wave should appear as:

a) A single peak at the fundamental frequency
b) Multiple peaks at harmonic frequencies
c) A continuous band of frequencies
d) Two peaks at the frequency and its reciprocal
Answer: a) A single peak at the fundamental frequency. A pure sine wave contains only one frequency component.

4. Which frequency is closest to the upper limit of typical human hearing?

a) 1000 Hz
b) 5000 Hz
c) 10000 Hz
d) 20000 Hz
Answer: d) 20000 Hz. Most young adults can hear up to about 20,000 Hz.

5. If you double the frequency of a tone, what happens to its period?

a) It doubles
b) It halves
c) It quadruples
d) It remains the same
Answer: b) It halves. Period = 1/frequency, so if frequency doubles, period is halved.