# Frequency Domain Another way to study sound is by examining how amplitude changes relative to frequency, producing graphs where the horizontal axis is expressed in **hertz** *(Hz)* allowing interpretation. These representations correspond to the *frequency* domain. The relationship between the time domain and the frequency domain is grounded in **Fourier** decomposition, which states that waves can be described as the sum or superposition of multiple sinusoidal waves, each contributing a specific frequency, amplitude, and phase. The more sinusoids are combined, the more accurate the approximation of the original wave becomes. To uncover the sinusoidal components of a signal, a *Fourier* *transform* is applied, with the Fast Fourier Transform *(FFT)* being the most common method. This algorithm allows us to **decompose** a waveform, identify its frequencies and amplitudes, and represent them as a spectrum in the *frequency* domain. {% hint style="info" %} Advanced **pitch-detection** algorithms analyze the *frequency spectrum* to identify the fundamental frequency of a signal, enabling applications such as dominant-frequency tracking. {% endhint %} --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.comdigis.com/user-guide-io/foundation/a-brief-history-of-digital-audio/frequency-domain.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.