Electronics Engineering (ELEX) Board Practice Exam

A change in frequency by a factor of ________ is equivalent to 1 octave.

1. 1

2. 2

3. 3

4. 4

The correct answer is: 2

In the context of musical intervals and frequencies, an octave is defined as the interval between one frequency and another frequency that is double (or half) that original frequency. Thus, if you take a reference frequency, multiplying it by 2 will result in the frequency one octave higher, while dividing it by 2 will yield the frequency one octave lower. This relationship stems from the way humans perceive sound; doubling a frequency is perceived as a significant change, resulting in the musical concept referred to as an octave. For example, if you start at a frequency of 440 Hz (which is the standard pitch for the musical note A4), one octave higher would be 880 Hz, demonstrating the direct relationship where a frequency change by a factor of 2 corresponds to a movement of one octave. Therefore, the correct answer regarding the factor for one octave is indeed 2.