104 Stefan Koelsch meaning quality. Other used the terms formal meaning (Alperson, 1994; Koopman & Davies, 2001), or formal signiKcance (Davies, 1994).The following will provide empirical evidence for the hypothesis that the the processing of intra-musical meaning is refected electrically in the N5 (or N500) component of the event-related brain potential (ERP): It will rst be described that the N5 is sensitive to harmonic context build-up, and to harmonic incongruity. Then, evidence is presented that the N5 speci cally interacts with the processing of the semantic inconguity of a word (which indicates that the processes underlying the generation of the N5 are related to semantic processes). At the end of this sec-tion, I will also provide some theoretical considerations, including other phenomena that can give rise to intra-musical meaning. Again, readers not familiar with ERPs may well skip the following and continue directly with the section on “Further in-tra-musical phenomena of tonal music”.Harmonic context buildup. The N5 was rst described in reports of experiments using paradigms in which chord sequences consisting of ve chords ended either on a music-syntactically regular or a music-syntactically irregular chord function (Koelsch et al., 2000, see Figure 2b). Regular chords at positions 1 to 5 elicited an N5 (see arrow in the left panel of Figure 2c), and the amplitude of the N5 declined to-wards the end of a chord sequence. This amplitude decline is taken to refect the de-creasing amount of harmonic integration required with progressing chord functions during the course of the cadence. A small N5 elicited by the (expected) nal chord of a chord sequence presumably refects that only a small amount of harmonic integra-tion is required at this position of a chord sequence. This phenomenology of the N5 is similar to that of the N400 elicited by open-class words (i.e., nouns, verbs, etc.): With progressing position of words in a sentence, the N400 amplitude also declines towards the end of a sentence (Van Petten & Kutas, 1990, see right panel of Figure 2c). That is, during sentence processing, a semantically correct nal open-class word usually elicits a rather small N400, whereas the open-class words preceding this word elicit larger N400 potentials. This is due to the semantic expectedness of words, which is rather unspeci c at the beginning of a sentence, and which becomes more and more speci c towards the end of the sentence (where readers already have a hunch of what the last word will be). Thus, a smaller amount of semantic in-tegration is required at the end of a sentence, refected in a smaller N400. If the last word is semantically unexpected, then a large amount of semantic is required, which is refected in a larger amplitude of the N400.Harmonic incongruity. Figure 2d shows ERPs elicited by regular and irregular chords at the nal position of the chord sequences shown in Figure 2b. Compared to regular chord functions, irregular chord functions typically elicit an early right an-terior negativity (ERAN, which is usually maximal around 150–200ms, and taken to refect neural mechanisms related to syntactic processing; for a review see Koelsch, 2009). In addition, irregular chords elicit an N5 with a larger amplitude than the N5 of regular chord functions (for studies reporting such N5 effects for melodies see Miranda & Ullman, 2007; Koelsch & Jentschke, 2010). This increase of the N5 amp-