Assuming that Horton is the elephant, several points add in favor of an affirmative answer.
First, the title of the book explicitly states that Horton hears a who (it even insists on that fact, given the exclamative form of the sentence).
Second, the author is a member of the medicine professionals, graded as doctor, which leads one to consider him as a reliable source a priori.
Third, the elephant pictured here does seem to hear something, as indicated by his ears well raised in attention, his alert look, as well as the surprise in his eyes.
It is hence safe enough to deduce that Horton (assuming the bloated white thing with wing-shaped ears is Horton) is hearing something. However little arguments tell us about the nature of what he's hearing, more explicitly, only the title of the book says so. But wouldn't that sentence refer to a precise point in the book's story and not necessarily to the picture displayed under it ? Book titles aren't always a trustable source of information about their contents. This rather tends to invalidate the first point.
Also, we must consider that more often than not, book cover illustrations are by no means reflecting an exact passage of the story they illustrate, being almost always mere conceptual suggestions, allegories. In that sense, the elephant with wing-shaped ears would be voluntarily displayed as hearing something, whereas in the story he would eventually not, or in a totally different context. This definitely invalidates the third point.
Remains the author's signature, seemingly attesting of the truth of these words (that Horton hears a who, that is). But, in this very case, it is difficult to conclude so. Doctors publications are by no means resembling, even by far, to child-targeting orange-painted cheap comics, unless the physicist in question deals with pedopsychiatry: I take that point for almost irrefutable. However, it is your duty to admit that 1°) what characterizes pedopsychiatry is by nature mental pathology, hence that 2°) mental pathologies are intrinsically characterized by symptoms of asociality which are the product of compulsive lies and deceit from the patient to others and to himself - which is in fact the essence of the pathology itself, thus 3°) considering the targeted audience, it is highly questionable that the book's title be true.
Who would say who to an elephant anyway?
I say no. With courage.
Would you rather see a psychologist or a psychoanalyst ?
RACC home - Bots-United: beer, babies & bots (especially the latter) "Learn to think by yourself, else others will do it for you."
Lol, I'd have to say sing opera... sometimes on cs_italy I like to sing to the radio, and kill anyone who breaks it.. c'mon, don't lie guys, I know I'm not the only one who sometimes sings to the radio.
Better C&C RTS song:
RA1's Hells March, or C&C's Industry?
[Edit]
I could swear one time when singing, I sang to a hostage, and he blushed.
Later-a-much, and LONG LIVE THE D!,
(Link>>>MarD's Moddin' Site<<<Link) MarD