Digital Sound & Music: Concepts, Applications, & Science, Chapter 4, last updated 6/25/2013
Figure 4.8 Frequency response graphs with linear and nonlinear scales for frequency
The range of frequencies within human hearing is, at best, 20 Hz to 20,000 Hz. The
range varies with individuals and diminishes with age, especially for high frequencies. Our
hearing is less sensitive to low frequencies than to high; that is, low frequencies have to be more
intense for us to hear them than high frequencies.
Frequency resolution (also called frequency discrimination) is our ability to
distinguish between two close frequencies. Frequency resolution varies by frequency, loudness,
the duration of the sound, the suddenness of the frequency change, and the acuity and training of
the listener's ears. The smallest frequency change that can be noticed as a pitch change is
referred to as a just-noticeable-difference (jnd). At low frequencies, it's possible to notice a
difference between frequencies that are separated by just a few Hertz. Within the 1000 Hz to
4000 Hz range, it's possible for a person to hear a jnd of as little as 1/12 of a semitone. (But 1/12
a semitone step from 1000 Hz is about 88 Hz, while 1/12 a semitone step from 4000 Hz is about
353 Hz.) At low frequencies, tones that are separated by just a few Hertz can be distinguished as
separate pitches, while at high frequencies, two tones must be separated by hundreds of Hertz
before a difference is noticed.
You can test your own frequency range and discrimination with a sound processing
program like Audacity or Audition, generating and listening to pure tones, as shown in Figure
4.9 Be aware, however, that the monitors or headphones you use have an impact on your ability
to hear the frequencies.