Properties of Sounds - Pitch (or shrillness) and frequency

1. Aim: To observe how tension in a wire affects the pitch and frequency of the sound produced.

2. Requirements: wooden board (80-90 cm long, 5 cm wide), two nails, thin metal wire, wedge-shaped wooden or plastic block, small rectangular blocks, hammer.

3. Procedure

• Hammer the nails into the wooden board near its two ends.
• Tie the metal wire tightly between the two nails.
• Place the wedge-shaped block under the wire near each nail.
• Pluck the wire lightly and observe if you hear sound and see vibration.
• Now add two or three small blocks under one wedge without changing the length of the wire.
• Observe the change in tension in the wire and pluck it again.
• Listen to the sound and note the difference in pitch and frequency.

4. Conclusion: Increased tension in the wire produces a higher frequency and the sound becomes shriller (higher pitch). Reduced tension produces a lower frequency and the sound becomes less shrill (lower pitch). This experiment shows that pitch depends on the frequency: a higher frequency creates a higher pitch, and a lower frequency creates a lower pitch.

The pitch of a sound