Table of Contents
What is Sound Wavelength?
Sound wavelength is the physical distance between successive compressions (or rarefactions) in a sound wave. It is inversely proportional to frequency: higher-pitched sounds have shorter wavelengths, while lower-pitched sounds have longer wavelengths. In air at room temperature, audible sound wavelengths range from about 17 mm (20 kHz) to 17 m (20 Hz).
Understanding wavelength is essential for acoustics, speaker design, room treatment, and musical instrument construction. Wavelength determines how sound diffracts around objects, how it interacts with room boundaries, and the dimensions needed for acoustic absorbers and resonators.
Formula
Common Musical Frequencies and Wavelengths
| Note | Frequency (Hz) | Wavelength in Air |
|---|---|---|
| A2 | 110 | 3.12 m |
| A3 | 220 | 1.56 m |
| A4 (concert) | 440 | 0.78 m |
| A5 | 880 | 0.39 m |
| C8 | 4186 | 0.082 m |
Frequently Asked Questions
How does temperature affect wavelength?
Temperature affects the speed of sound. In air, the speed increases by about 0.6 m/s per degree Celsius. At 0 degrees C, v is about 331 m/s; at 20 degrees C it is about 343 m/s. Higher speed means longer wavelength at the same frequency.
Why does wavelength matter for speakers?
A speaker efficiently radiates sound when its diameter is comparable to the wavelength. Small tweeters handle high frequencies (short wavelengths), while large woofers handle low frequencies (long wavelengths). This is why multi-driver speaker systems with crossover networks are used for full-range reproduction.
What is the wavelength of human speech?
Most speech energy falls between 100 Hz and 4 kHz, corresponding to wavelengths from about 3.4 m down to 8.6 cm. The fundamental frequencies of the human voice range from about 85 Hz (deep male) to 300 Hz (high female), with harmonics extending much higher.