"Heartbreak Hotel" is one of the first rock and roll songs I can remember hearing. I was ten years old, riding in my parents' 1955 Chevy from Eglin Air Force Base, where we lived, to Pensacola for some shopping. My reaction at the time was that Elvis' staccato delivery of "You-make-me-so-lone-ly-ba-by" sounded like a broken-down helicopter. Later, as my scope of musical appreciation expanded to include the blues, I came to like the song.
One thing I didn't notice was the piano accompaniment. The two quick instrumental notes that follow the opening line, "Well, since my baby left me," and subsequent sung lines seem, on careful listening, to be guitar and piano chords struck simultaneously. The piano is first heard by itself starting at about 0.50 in the audio track above, doing rapid arpeggios in a high register, but softly. At about 1.32, during the short instrumental bridge, the piano comes through more boldly. If you listen to the song attentively, you hear the piano clearly, but if you're using it as background music, it's almost subliminal. Even if you do hear it, it doesn't command your attention, even though it's played very well. This is the mark of a first-rate studio musician.
The musician in question here was Floyd Cramer, who backed up Elvis and other stars for years. In 1960, though, he became known on his own because of the success of "The Last Date", which reached number two on the Billboard pop survey.
"The Last Date" featured a style of piano playing that Cramer may have invented, called "slip note." A finger lightly touches a key one note off the intended one, producing a soft sound, then slides onto the intended key and hits it with normal force. This subtle glissando imparts a quality of eeriness to an otherwise pretty but forgettable tune. This brings to mind the kerfuffle over Auto-Tune, a software program used by some pop artists to correct notes in their singing, generating a finished product in perfect pitch. As David Hadju has sagely pointed out in The New Republic, the real problem with Auto-Tune, to the extent that there is a problem, is not that it gives an artificial boost to the untalented, but that it could smother what is often best in music, that is, the slight imperfections that make it memorable. "Bessie Smith, processed through Auto-Tune, would have all the soul of Siri."