Search

As a child grows up the formants of their vowels move down in frequency and the spacing of the harmonics that determines voice pitch decreases. Perceptually, these variables determine who listeners hear speaking (child, woman or man). In a logarithmic-frequency spectrum, the envelope with its formant peaks, moves toward the origin as a unit, without changing shape as a child grows up. Similarly, the harmonics, which constitute the fine structure of the spectrum, move toward the origin as a unit without changing shape, but at a different rate. This paper describes neuromagnetic studies which show that the generator associated with voice pitch is in Heschl's gyrus just lateral to primary auditory cortex, while the generator associated spectral envelope position is in planum temporale, some distance behind the pitch activity generator. The posterior generator is close to the location of the large N1m that typically accompanies the onset of acoustic energy of any sort. The pitch processing component of the N1...

Early attempts to locate brain regions involved in pitch processing employed sequences of notes with no pitch, fixed pitch, and melodic pitch. They revealed a region of Heschl's gyrus lateral to primary auditory cortex where sequences with pitch produced more activity than noise, and regions where melody produced more activation than fixed pitch (in planum polare and the superior temporal sulcus). Subsequent research has focused on the fixed pitch region in Heschl's gyrus and the degree to which the activity is pitch specific. Recently, MEG techniques have been developed to compare the responses to sequences of notes as they occur within bars of music, and to separate current sources associated with attention to melody. This paper illustrates how the techniques can be used to investigate the hierarchy of pitch and melody processing as it occurs in four bar phrases with brass instruments. The experiments show that a given note elicits a larger response when it is part of a melody and the increment is associated with a source beyond auditory cortex. The paper shows how we might track the responses to orchestral instrument sounds presented in a musical context as they proceed through auditory cortex and beyond the temporal lobes.