McLuhan's "electric age" raises the question as to how the medium of electricity affects the message. The electric age was a long time coming, starting, perhaps, with Mary Shelley's Frankenstein at the beginning of the 19th century, once the electrons started to flow as electric current, instead of just being stored up statically as a positive electric charge (i.e. lacking electrons with negative charge) in ἤλεκτρον (amber) by rubbing the amber that could be discharged with a mighty spark, about which the Greeks already knew, not to mention Zeus' lightning bolts. Then in the early-to-mid-19th century came Faraday's experimenting and Maxwell's field equations for electromagnetism that enabled the reciprocating dance between the flow of electrons and magnetic force-field to be mathematized in four neat equations. Along with that, on the technological side, the invention of the telegraph (literally: far-writing) for sending Morse-coded electron messages along wires to write in far-off places revolutionized communications. Here the speed of the medium had a huge effect on messaging; the world grew smaller through having electrons assuming the wings of Hermes. Even the swiftest horses could not compete.
Excitation of the electrons took off with the incandescent lamp,
with electrons emitting pure bearers of light-energy (photons) on becoming
mightily excited in a wire enclosed in glass along with an inert gas. Then,
instead of sending little electron messages along wire, there
came the invention of the radio, which wirelessly and
concentrically sent out (trans-mitted) messages as
electromagnetic signals that could be deciphered at the other
end by a radio receiver. For such messaging, Claude Shannon later developed the necessary mathematics for technologically managing signal-loss through electromagnetic noise. Radio transmission accelerated and contracted the world still further, tying a mass public into its messages in a way that exceeded the massifying of society already accomplished by newspapers, which themselves emerged as a powerful medium in the early 19th century.
The electromagnetic medium has engendered a yet more massified, fake togetherness. Today, anonymous 'people' have long since become the ubiquitous, constantly addressed 'subject' of the mass-media age, whose massified opinions matter solely in anonymous, massified form, as in 'People think this...', or 'They do that...' or the ubiquitous fake 'we' of democracy, as in 'What are we to do about ...?' The ongoing discussion of fake news enabled by cyberworld platforms leaves entirely out of account the fakeness of the 'we' in 'our' democratic societies, which the media's talking heads are loath to even mention for fear of offending their mass audiences. Do I hear the word 'sycophancy'?
To come now to music: in the first half of the 20th century, along with inventors from the U.S. radio and electronics industry, Les Paul experimented with electrifying the guitar, succeeding finally in making the first solid body electric guitar in the 1940s. Magnetized pick-ups positioned beneath the guitar's strings
picked up their vibrational motion, thus inducing an electric
current that was passed from the guitar along a wire to the
amplifier. Boom! Electric music was born, exciting electrons for
the sake of the musical human ear. This culminated in the 1950s in rock
music, a prancing & dancing with electrons in which the
electronic phenomena themselves became musical. It was not
merely a case of amplifying volume, but of sui generis
electro-acoustic phenomena attuning our shared psyche. Such sounds include the feedback, overdrive, distortion, flanging, phasing, fuzzing and wah-wah-ing of the electric guitar that has been rapidly mastered by outstanding guitarists within just a few decades. The energy of electrons was
harnessed for powerful acoustic experience in stadium concerts and also recorded on
wax, shellac, vinyl and finally digitized in CD and mp3
recordings. The code signalling how the electrons were to dance could be reproduced easily million-fold in these latter media.
Electrons came to be bearers of musical messages setting the times'
moods into vibration, thus attuning us to the world in a way
different from lute, cello, flute and harpsichord. If the stately classical music of courtly times had given way in Europe to the more dynamic movements of horses after the French Revolution (cf. e.g. Beethoven), in the 20th century the electronic media came to dominate the musical messaging, just as communication in general became electronically massified. The electronic medium itself gives us the message of electrification, culminating in today's digitization of the world in which not only our age's mind is quickly adapting to algorithmic entrapment, but also to which our age's psyche has rapidly become more and more musically attuned.
Further reading: Thinking of Music, The Digital Cast of Being, Rafael Capurro's 'Angeletics Notes'.