Subjective TonesWhen two single-frequency tones are present in the air at the same time, they will interfere with each other and produce a beat frequency. The beat frequency is equal to the difference between the frequencies of the two tones and if it is in the mid-frequency region, the human ear will perceive it as a third tone, called a "subjective tone" or "difference tone". The difference tones are always present, but they can be made prominent by using two high, clear tones like the notes of a flute. With two flutes you can produce a "trio for two flutes". This phenomenon can also be produced with one brass instrument (multiphonics). If a French horn player plays one note and hums another, then the subjective tone which is the difference between them can sometimes be heard clearly. One important role of subjective tones is the missing fundamental effect whereby a correct sense of pitch for a musical sound may be maintained even if the poor fidelity of the sound reproduction has filtered out some of its lower harmonics.
|
Index Hearing concepts Traveling wave concepts | ||
|
Go Back |
Missing Fundamental Effect
|
Index Traveling wave concepts Hearing concepts | ||
|
Go Back |
MultiphonicsOne of the applications of subjective tones is the production of three tones by a single brass player. The player plays a note in the usual way but in addition hums a second note into the mouthpiece. The beat frequency between these two notes produces a third tone. Such tones are sometimes called multiphonics. |
Index Traveling wave concepts Hearing concepts | ||
|
Go Back |