White noise
What frequencies make up white noise?
Author:
Title 4
Learning objectives :
This activity allows students to discover the frequency composition of white noise and to understand its importance as a reference in acoustics. It develops critical thinking by comparing auditory perception and scientific analysis.
Concepts covered
Sound spectrum, Audible frequencies, Spectral analysis, Power spectral density, Analogies between wave phenomena
What students will do :
The student first explores white noise sensorially by listening to it via the FizziQ sound library, then formulates hypotheses about its frequency composition. It then uses the frequency spectrum to objectively analyze its composition and performs several measurements to verify the stability of the spectrum. Based on their observations, the student characterizes white noise and establishes an analogy with white light.
What is required :
Smartphone with the FizziQ application, A quiet environment, Optionally headphones for better listening
Scientific background :
White noise is a random signal characterized by a constant power spectral density over the entire range of audible frequencies (generally 20 Hz to 20 kHz for humans). Its name comes from analogy with white light which contains all wavelengths of the visible spectrum at equal intensity. Mathematically, ideal white noise would have an autocorrelation function which would be a Dirac pulse, indicating that the signal values at two different times are completely uncorrelated. In the spectral analysis performed with FizziQ, the frequency spectrum uses the fast Fourier transform (FFT) to decompose the time signal into its frequency components. For perfect white noise, this spectrum would be a flat horizontal line. The slight variations observed are due to generator imperfections, microphone limitations, and environmental resonances. White noise is used as a reference in acoustics, sound masking and engineering to test the robustness of systems.