Melinda Feldmann Combination Tones

What is a Combination Tone? Combination Tone In musical acoustics, faint tone produced in the inner ear by two simultaneously sounded musical tones. Because such tones are caused by the ear rather than by the external source of the sound, they are sometimes called subjective, or resultant, tones. There are two varieties: difference tones (D) and summation tones (S), generated respectively by the frequency differential of the two pitches or the sum of their frequencies. According to the Encyclopedia Britannica:

“When two pure tones are played together, it sometimes sounds as though a third tone is also present. For example, a person simultaneously hearing two loud tones of 800 and 1000 hertz may also report hearing another, quieter tone at about the pitch one would expect from a 200 Hertz stimulus. More generally, if two generating tones, or primary tones, of frequency U (for the upper tone) and L (for the lower tone) are played together, people will under some conditions report hearing a difference tone (or first difference tone) that sounds like a tone presented at frequency U - L, despite the fact that waveform analysis may show no sound wave at that frequency.” Expanded Explanation of Different Types of Combination Tones

Expanded Explanation Continued “Similarly, people sometimes report hearing, in addition to or instead of the first difference tone, a second difference tone at approximately the pitch one would expect from a stimulus of frequency 2L - U (in other words, 600 hz, if the generating tones are 800 and 1000 hz). British Psychologist Edward B. Titchener also describes a third difference tone at 3L - U and a summation tone at U + L. Other investigators report tones at 3L - 2U, 4L - 3U, 2U - 2L, 3U - 3L, and other frequencies. These are known as combination tones. In stimuli with prominent overtones (overtones have a frequency that is an integer multiple of the fundamental frequency of the stimulus, such as 2U, 3U, 4U, etc.), people sometimes report hearing combination tones arising from the overtones.”

Why Do We Hear Combination Tones? It is widely believed that sound frequencies picked up by the inner ear create the third tone, then transmitting the information to the brain, causing the listener to hear the combination tone. However, when using headphones with one pitch in each ear, listeners still reported hearing combination Tones. One optional theory uses the Bohlen-Pierce Scale. Example from Bohlen-Pierce Scale: C - G - A, tuned to harmonics 3, 5, & 7.

Visual Example of Difference Tones

Audio Example of a Combination Tone Listen to pitch #1:Listen to pitch #2: Now listen to the two pitches, combined. When they are played simultaneously, the two pitches create a third pitch, the Combination Tone: See if you can hear the combination tone in the example below. Listen to the two individual pitches first, then listen to them together to see if you can hear the combination tone. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Video Example of a Combination Tone (Also known as the Tartini Tone)Tartini Tone

Sources Bohlen-Pierce Scale. (n.d.) Retrieved from Combination Tones. (n.d.). In Encyclopedia Britannica online. Retrieved from Interference Beats and Tartini Tones. (n.d.) Retrieved from Schwitzgebel, Eric (n.d.). Difference Tone Training. Retrieved from Tartini Tones on Pennywhistles. (December 4, 2007). Retrieved from