Which term refers to frequencies that are fractions of a fundamental frequency?

The term that describes frequencies that are fractions of a fundamental frequency is sub-harmonics. Sub-harmonics arise in various physical systems where they represent frequencies that are lower than the fundamental frequency. For instance, if the fundamental frequency is represented as a base frequency, sub-harmonics would be its divisions, such as half of the fundamental frequency or a quarter of it. This concept is essential in vibration analysis as it helps in identifying potential issues in machines, as sub-harmonics can indicate specific operational characteristics or anomalies.

In contrast, harmonics refer to frequencies that are integer multiples of the fundamental frequency and are typically used in contexts related to sound and musical pitches. Beats represent a phenomenon related to the interference of two close frequencies and are not characterized as fractions. Overtones refer to frequencies in a waveform that are higher than the fundamental frequency and are typically whole-number multiples. Understanding these distinctions helps to apply the correct terminology in vibration analysis and enhances the interpretation of frequency data in practical scenarios.