Waveforms
A waveform visually represents a sound waves journey through a medium over time. Learn how waveforms illustrate sound characteristics.
Any waveform has four fundamental characteristics:
Don't confuse a waveform with the true nature of sound. Sound waves are longitudinal, where particle vibrations occur in the same direction as the wave travels. However, waveforms are often shown as transverse in audio diagrams for easier visualization.
Frequency
Frequency is how many complete waves there are per second passing a certain point. The frequency indicates the rate of pressure variations or cycles per second of a wave. Frequency is measured in Hertz.
The frequency of a sound determines the pitch; the sensation of how low or how high a sound is.
- Lower frequency sound waves have longer wavelengths and lower pitch
- Higher frequency sound waves have shorter wavelengths and a higher pitch
The frequency range in which humans can hear is 20Hz to 20,000 Hz and is called the audible range, or the audio spectrum.
Wavelength
The distance between two successive points that are in phase (e.g., from crest to crest or trough to trough). Wavelength is inversely related to frequency.
Amplitude
Amplitude is the height of the wave, which determines the loudness of the sound. Higher amplitude means a louder sound.
Amplitude is measured in two ways:
- Zero to peak value which measures the maximum positive or negative signal level.
- Root-mean-square (RMS) value measures a more meaningful average level, like that at which humans hear.
Velocity
The velocity is the speed and direction of a sound wave. Sound waves travel at different speeds through different mediums. Through the air, sound travels at 344 meters per second.
Generally speaking, the denser the medium the faster sound travels through it.
To find the velocity of a wave the following equation is used: Velocity (V) = Frequency (f) x Wavelength (λ)