So now, in this lesson, let’s turn to the critical question. Do these differences in major and minor music correspond to differences in the vocalization of individuals when they're in different emotional states. And is the reason that the excitement of the major scale and the subdued nature of a minor scale in music is the reason that emotion is conveyed. Because the music is imitating the tonal characteristics of individuals that are expressing emotion, when they're excited or subdued. And the various states that go with those two categorizations of emotion. So let me begin by reminding you, I showed you this slide before, that the vocal tract is a perfectly good musical instrument. It has all the characteristics of a musical instrument. A source of vibration, the vocal chords, modulation of that vibration by the rest of the vocal tract above the larynx and that the phones. The sound signals that come out of the mouth are not really any different than the sound signals that are generated by the vibrating string and body of a violin. Or the air column and reed in a wind instrument and many other examples that you can think of. So the question then is how do you compare a speech and music in different emotional states? So there's several ways in which this can be done. And here, we're looking at speech and we're comparing it to music and the metric in this example is the fundamental frequency. So let's take speech. So we're talking about, and this was done by, again, using the database of actors in different emotional states, expressing speech in different emotional states. Excited versus subdued, the excited in red the subdued in blue and the overlap between those in purple. And what you see in either the expression of actors uttering single words or monologues. That is a few paragraphs of words spoken in one or another emotional states. Is that when the speakers are in an excited emotional state, again, those are the red columns here. The fundamental frequency, whether it's a male or female speaker, is considerably higher. So, the fundamental frequency when people are actors in this database, in an analysis of this database, are speaking in a subdued manner. The fundamental frequencies tend to be low, as you might imagine, 100 Hz or 192 Hz on average for males and females respectively. When they're excited, the fundamental frequency goes up. And again, this is true whether it's in single words or monologues. Well, why should that be? I think the reason is pretty obvious. Let's go back to this slide. So, when a person is excited, the tension on their vocal chords is increased by virtue of a muscular tension on the vocal chords that changes their vibratory frequency. That's what causes the fundamental frequency of the harmonic series as being generated by the vibration of the vocal cords to increase when a person is excited. And to be less when that person is in a subdued, relaxed, sad, unexcited state. The rest of the vocal tract is then operating on vibratory power that's coming from the vocal cords that's quite different giving these different fundamental frequencies, whether it's single word, or a monologue. Now the question is, does that characteristic, that tonal characteristic, the fundamental frequency that's defining whether a person is excited, or subdued in speech is that the same as music. Well, let's make the comparison, so here is major music, here's minor music, major music in red, minor music in blue, overlap in purple. For classical melodies and for the folk melodies. And again, you see what I said before, that for the major melodies, the fundamental frequency, again, because we're talking about the dyad now. That's the implied fundamental frequency of the two tones together, is less in minor music than it is in major music, and the same thing applies in folk music. The fundamental frequency, the implied fundamental frequency, is less in minor music than it is in major music, when the composer intends to convey excitement versus a subdued emotion. So, the general idea is then musical tonality conveys emotion by imitating the tonality in speech or vocalization in different emotional states. And the parallel is between music in major and minor scales and speech in excited and subdued states. And the reason I would argue and ask you to think about, the reason that a major scale conveys the sense of brightness, excitement, etc. And a minor scale conveys a sense of a lack of excitement, a lack of arousal, sadness, is because those two scales are imitating the emotional state in tonality that's expressed in speech by the tones and their fundamental frequencies that are used in speech.
