Beats

Definition

Beats are the periodic variations in the amplitude or loudness of a sound that occur when two sound waves of slightly different frequencies interfere with each other. This phenomenon arises from the constructive and destructive interference of the two waves, resulting in a pulsing or throbbing effect in the perceived sound.

5 Must Know Facts For Your Next Test

1. The frequency of the beats is equal to the difference between the frequencies of the two interfering sound waves.
2. Beats are commonly used in tuning musical instruments, as the frequency of the beats indicates how much the two tones differ in pitch.
3. The amplitude of the beats is determined by the relative amplitudes of the two interfering sound waves.
4. Beats can be used to measure small differences in frequency, as the beat frequency is directly proportional to the frequency difference between the two waves.
5. Resonance can amplify the effect of beats, as the constructive and destructive interference is more pronounced at the resonant frequencies of a system.

Review Questions

• Explain how beats are produced and how the frequency of the beats is determined.
  • Beats are produced when two sound waves of slightly different frequencies interfere with each other. The frequency of the beats is equal to the difference between the frequencies of the two interfering sound waves. For example, if one wave has a frequency of 440 Hz and the other has a frequency of 442 Hz, the resulting beat frequency will be 2 Hz. This pulsing or throbbing effect is caused by the constructive and destructive interference of the two waves, where they reinforce each other at some points and cancel each other out at other points.
• Describe the relationship between beats and resonance, and how this interaction can be used in practical applications.
  • Resonance can amplify the effect of beats, as the constructive and destructive interference is more pronounced at the resonant frequencies of a system. This is particularly useful in tuning musical instruments, where the beats between the instrument's sound and a reference tone can be used to adjust the instrument's pitch to match the desired frequency. The frequency of the beats indicates how much the two tones differ in pitch, allowing the musician to fine-tune the instrument until the beat frequency is minimized, indicating that the two tones are in tune.
• Analyze how the amplitude of beats is determined and the significance of this relationship in the context of sound interference and resonance.
  • The amplitude of the beats is determined by the relative amplitudes of the two interfering sound waves. If the two waves have equal amplitudes, the beats will have the maximum possible amplitude. As the difference in amplitude between the two waves increases, the amplitude of the beats will decrease. This relationship is important in the context of sound interference and resonance because the relative amplitudes of the interfering waves can be used to control the strength of the beats. In systems where resonance is involved, the amplitude of the beats can be used to identify the resonant frequencies, as the beats will be most pronounced at these frequencies due to the constructive and destructive interference being amplified by the resonance.

Related terms

Interference: The interaction of two or more waves, such as sound waves, resulting in a new wave pattern.

Resonance: The tendency of a system to oscillate at a greater amplitude at some frequencies than at others, known as the system's resonant frequencies.

Constructive Interference: The process by which two or more waves combine to form a resultant wave of greater amplitude.