Should LOL be LA? "Aloud" and "Out loud", a history
The bias against 'out loud'
An excellent answer posted and then withdrawn by Josh61 notes that "out loud" has endured considerable opprobrium from usage experts of the past and present. Webster's Dictionary of English Usage (1989, reprinted five years later as Merriam-Webster's Dictionary of American Usage) lays out the details of the criticism:
out loud Out loud was once widely decried as an error for aloud, and it is still sometimes described as a colloquialism to be avoided in formal writing. Its first recorded use was in the early 19th century:
Lord Andover in the presence of Lord and Lady Sufolk and speaking out loud — Maria Edgeworth, letter, 1821 (OED Supplement)
Its heyday as an object of criticism came about a hundred years later, when American commentators such as MacCracken & Sandison [Manual of Good English] 1917, Ball [Constructive English] 1923, Woolley & Scott [New Handbook of Composition] 1926, and Krapp [A Comprehenive Guide to Good English] 1927 routinely prescribed against it in their books. Its use continued to be common, however, and its notoriety eventually diminished. It now survives as a usage topic chiefly in composition textbooks for high school and college students.
Our abundant written evidence for out loud shows clearly that it is not a colloquialism. We would agree that aloud is more likely in solemn writing, but in general use the two terms are essentially interchangeable: ...
A revised edition of WDEU, titled Merriam-Webster's Concise Dictionary of American Usage (2002) lightly updates the entry cited above to note that Bryan Garner, Modern American Usage (1998)—like the aforementioned composition textbooks for high school and college students—makes out loud "a usage topic." Here is the entry for aloud and out loud in Garner, Garner's Modern American Usage, second edition (2003):
aloud; out loud. The latter is colloquial when used in place of the former in expressions such as read out loud. Because of this—and because read aloud is 12 times as common as read out loud in modern print sources—read aloud should be preferred in edited prose. [Examples omitted.]
The Ngram for "read out loud" (blue line) versus "read aloud" (red line) for the period 1900–2005 corroborates Garner's numbers:
In 2003, the percentages for the two terms were .0000112382% for "read out loud" and .0001371208% for "read aloud"—the percentage for the latter being slightly more than 12 times as high as the percentage for the former; the numbers for 2005 indicate that the "read aloud" was slightly more than 10 times as frequent as "read out loud" in Google Books content published during that year.
In any event, the Google Books data indicates that in published writing "read aloud" continues to be far more common than "read out loud," whether "read out loud" is "colloquial" or not. I'm not sure how to separate those results into instances of "solemn writing" and "not solemn writing," but I suspect that the preference for "read aloud" is not limited to the former.
A very different picture arises when we compare "laugh out loud" (blue line) to "laugh aloud" (red line) for the period 1900–2005:
The percentage for "laugh out loud" has skyrocketed since the middle 1970s, while the percentage for "laugh aloud" has remained essentially flat. This raises the possibility that even solemn texts are beginning to approve of "laugh out loud," or that few solemn texts touch either phrase.
The earliest criticism of "out loud" that I could find is in a Google Books search is from 1916. From Robert Utter, Every-day Words and Their Uses: A Guide to Correct Diction (1916):
Out loud. Out loud for aloud is a colloquialism.
And a year later, from Francis Ball, Constructive English (1917):
aloud. Do not use 'out loud' for aloud:
She was reading the book aloud.
When and where did "out loud' for 'aloud' originate?
Interestingly, Robert Utter, A Guide to Good English (1914), written two years before his Every-day Words and Their Uses, has (unrelated) occasion to quote Keats's sonnet, "On First Looking into Chapman's Homer," which includes these lines:
Yet did I never breathe its [Homer's epic's] pure serene
Till I heard Chapman speak out loud and bold:
This points to a complication that "out loud" presents: loud may mean "audibly" (as in "Till I heard Chapman speak aloud and bold") or it may mean "loudly" (as in "Till I heard Chapman speak out loudly and boldly"). It is even possible in some situations to read loud as an adjective referring to a preceding noun rather than as an adverb referring to a preceding verb (as in "Till I heard loud and bold Chapman speak out"). So in some situations, "out loud" can be taken in multiple senses.
Although the OED points to Maria Edgeworth's letter written in 1821 as the first instance in which "out loud" means "aloud," earlier examples could be interpreted in the same sense. For example, from John Fletcher & Philip Massinger, The Double Marriage (1619–1622/1647):
Virolet. Oh, hard condition of my misery! Unheard-of plagues! when to behold that woman,/That chaste and virtuous woman, that preserv'd me,/That pious wife, wedded to my afflictions,/Must be more terrible than all my dangers!/Oh, Fortune, thou hast robb'd me of my making,/The noble building of a man demolish'd,/And flung me headlong on a sin so base/Man and mankind contemn; e'en beasts abhor it/A sin more dull than drink, a shame beyond it;/So foul, and far from faith, I dare not name it,/But it will cry itself out loud, Ingratitude. Your blessing, Sir!
From Samuel Foote, The Mayor of Garratt (1763/1769):
Major [Sturgeon]. A goodly company!
[Jerry] Sneak. Ay, and then sometimes we have the Choice Spirits from Comus's Cout, and we crack jokes, and are so jolly and funny : I have learnt myself to sing "An old woman clothed in grey." But I durst not sing out loud, because my wife would overhear me; and she says as how I bawl worser than the broom-man.
From Louis-Sébastien Mercier, The Nightcap, volume 2 (1785):
Now a round temple, of entire alabaster, was, in the twinkling of an eye, raised about me : I heard a voice call out, Name, then, among the children of men, and who await the splendour of the eternal day, name him thou would wish to see. —— Several names crowded on my memory ; Sesostris, Abraham, Alexander, Caesar, Charlemagne, Cromwell, &c. when, in my confusion, I called out loud, Mahomet? I wanted to say—
From the introduction by Sir Richard Bulkeley to Prophetical Extracts (after 1793):
Before hell he saw, and had a sensible distinct perception, in the spirit, of dreadfully great and thick darkness, and of an unparalleled hideous, bitter smoke, vapour, exhalation, fume, and stench. He also heard, amidst the darkness, inexpressibly ugly, hideous voices, crying out loud, " Wo unto us! O ye hills!" &c.
From Jenkin Jones, Hobby Horses: A Poetic Allegory, in Five Parts (1797):
She resolutely dares the bell to ring,/Looks round, coughs quite out loud, and tries to sing,/Stalks to her harpsichord, unfolds the book,/And has the impudence to play Malbrook.
And from Old Nick: A Satirical Story (1801/1803), also quoted in The Monthly Review, Or, Literary Journal (1801):
"You promised to tell, sir, and you know, that a woman's curiosity is———" As restless as St Vitus's dance! therefore to give you ease, I will tell you. Now, O Goddess of Chastity! send, O send thy sylphs to influence my words and guide my pen! My invocation being at an end, be pleased, madam (for I swear I will not speak out loud), be pleased to lend me your ear—Pooh, that won't do—Do just move your wig a little on one side—there, that'll do.
Some of these early instances of "out loud" seem ambiguous as between "out loud" in the sense of "in a normal tone of voice" and "out loud" in the sense of "loudly". But others tend rather strongly toward the first interpretation—certainly as much as Maria Edgeworth's example does.
The ignored problem of 'aloud'
The word aloud has been found in English texts dating to the thirteenth century and has attracted no condemnation from usage mavens of the past century—and therefore no close scrutiny from sources with a critic-critical focus such as WDEU. But it appears that aloud has an unremarked twist of its own: in its earliest occurrences, and for a long time thereafter, it seems to have had the sole meaning "loudly" and only considerably later the meaning (as Merriam-Webster's Eleventh Collegiate Dictionary [2003] rather oddly puts it) "with the speaking voice."
So when Cordelia in King Lear says,
Alack, 'tis he; why he was met even now/As mad as the vex'd Sea, singing aloud,/Crown'd with rank Fenitar, and furrow Weeds,
she means aloud in the sense of "loudly." That at any rate is the conclusion put forward in Alexander Schmidt, Shakespeare-Lexicon: A Complete Dictionary of All the English Words, Phrases and Constructions in the Works of the Poet (1874):
Aloud, with a raised voice: [citations to 22 occurrences in Shakespeare's plays omitted].
The entry for aloud in the full-length Oxford English Dictionary (1971) doesn't offer a meaning that seems especially close to "in a normal tone of voice":
1. In a loud voice; with great noise; loudly. [First cited example, from Chaucer, Troylus and Creseyde: "The kinges foole is wont to crie aloud." Other examples omitted.] b. doubtfully attrib. [Examples omitted.] 2. fig. (colloq.) [Examples omitted.]
One citation (from 1767) beneath definition 1 seems to correspond to MW's "with the speaking voice" meaning, but OED doesn't present that meaning as something distinct from the "loudly" meaning, so it's difficult to say whether the OED considers the cited instance to be the first occurrences of aloud in the represented sense. Here (at somewhat greater length) is that instance, from James Fordyce, Sermons for Young Women (1767) [combined snippets]:
For the sake of variety and improvement, when in her own house, some one of the company would often read aloud, while she ["a lady noble by birth, but more noble by her virtues"] and her female visitants were thus employed [doing needlework].
John S. Kenyon, "Aloud, Loud, and Out Loud," in Philological Quarterly, volume 5 (1926), seizes on this example as being inconsistent with OED's main definition of aloud, and takes both OED and Webster's New International Dictionary (1909) to task for failing to account for the "expressed with ordinary strength of voice" meaning:
Under aloud, the Century Dictionary gives as one definition, "With the natural tone of voice as distinguished from whispering." The Standard Dictionary gives equivalent definitions: "(1) With ordinary strength of voice; audibly; opposed to in a whisper. (3) Using the voice; out loud; opposed to silently; as, Did you read aloud?"
These definitions are adequate and give probably the commonest meaning of aloud in current use. Equivalent definitions are, however, quite lacking in the Oxford and Webster's New International dictionaries. For aloud the Oxford has only, "In a loud voice; with great noise; loudly." Yet under this is quoted : "1767 Fordyce, One of the Company would often read aloud," in which aloud obviously has the meaning, "vocally," not "loudly." Furthermore, s.v. read, 11, the Oxford has, "to utter aloud, to render in speech," with the note, "To read aloud is frequently used to distinguish this sense of the word from 5 {'to peruse without uttering in speech'}." Under the second verb think, B 3, occurs the note, "To think aloud: to express one's thoughts by audible speech as they pass through the mind." Though this definition strictly would include whispering, it probably is not so intended.
Identical with that of the Oxford is the definition of aloud in the International, except that the latter adds "audibly." But "audibly" applies as well to whispered as to vocal utterance, as is indicated by the International's definition of audible: "Capable of being heard; as, an audible voice or whisper." Like the Oxford, however, the International uses aloud in definitions in the sense of "vocally"; e.g., s.v. read, aloud meaning "vocally" occurs at least four times, and s.v. whisper, n., occurs the expression, "In whispering, as opposed to speaking aloud,"—an expression apparently taken from Sweet (cf. his Primer of Phonetics, p. 10).
The present-day common meaning of aloud = "vocally" occurs at least four times in Shakespere: Much Ado [About Nothing], II, i, 108, "I say my prayers aloud"; Tw[elfth Night, II, v, 94, "The spirit of humours intimate reading aloud to him!" Rom[eo] and Jul[iet], II, ii, 161, "Bondage is hoarse and may not speak aloud"; Cymb[eline], I, vi, 26, "So far I read aloud." It seems likely that this is the sense used figuratively in Oth[ello], II, i, 5, "Methinks the wind hath spoke aloud at land."
In this last paragraph, Kenyon makes a strong case for the existence of the "in a normal voice" sense of aloud going back to the late 1500s. By way of confirming Kenyon's remark about the treatment of aloud in Webster's New International Dictionary (published multiple times between 1909 and 1933), here is the relevant entry from that dictionary:
aloud adv. With a loud voice or great noise; loudly; audibly. [Only cited example:] Cry aloud, spare not, lift up thy voice. Is[aiah] lviii. 1.
As late as Webster's Sixth Collegiate Dictionary (1949) Merriam-Webster offers a single very brief definition of aloud:
aloud adv. Loudly; with the speaking voice.
Finally, the Seventh Collegiate (1963) acknowledges that the two definitions are distinct, although it goes on to characterize the meaning "loudly" as archaic:
aloud adv 1 archaic : LOUDLY 2 : with the speaking voice
This, with the minor elaboration that the archaic meaning of aloud is "in a loud manner: LOUDLY," remains Merriam-Webster's treatment of the word today. But MW's view that aloud in the sense of "loudly" is archaic is rather difficult to square with the dozens of instances of the phrase "shouted aloud" that a Google Books search finds from books published in the past several decades. For example, from John Deane, Undertow (2002):
He shouted aloud his loss and his anger. He bunched his fists against the low, grey clouds. The white sun had vanished from the western rim of the sky and the first, even colder, winds of night had begun to slice along the bay.
From P.D. James, The Lighthouse (2005):
There was no help anywhere on earth, nor on those dead spinning worlds with their illusionary brightness. No one would be listening if he gave way to this almost irresistible impulse and shouted aloud into the unfeeling night, Don't take away my words! Give me back my words!
From Sam Gayton , The Snow Merchant (2011):
'I'm sure I have. But what was it?'
And Noah and Lettie cast back into their minds to catch the memory, like a pair of fishermen throwing their lines downstream, until at once they both shouted aloud:
'Clams on Leutha's Wood!'
It's difficult to make the case that readers are to understand "shouted aloud" in these instances as meaning "shouted with the speaking voice." Today, people sometimes say things like "shouted aloud" when they mean "shouted loudly"—without any intention to sound archaic.
Conclusions
The words "out loud" have appeared following verbs such as call, cough, cry, roar, say, shout, sing, and speak since long before 1821. But the sense of the resulting expressions is not always clear: a person who "sings out loud" may be singing loudly or singing at a volume equivalent to that used in normal conversation. And similarly a person who "sings aloud" may be singing loudly or singing at the equivalent of conversation volume.
Because a couple of important dictionaries—the OED and Merriam-Webster—have historically done such a poor job of delineating the meanings of aloud, it is hardly surprising that people are uncertain about whether aloud and "out loud" are interchangeable terms. The late-blooming criticism of using "out loud" to mean "aloud" finds its counterpart in the dictionaries' slowness to recognize the existence of two distinct and active meanings of aloud.
In the absence of consistent authoritative guidance, it makes sense for writers—whether solemn or jocular—to follow predominant usage, when such a thing exists. As I write this, that means preferring "read aloud" to "read out loud" and preferring "laugh out loud" to "laugh aloud." But no one is going to arrest you for rejecting predominant usage and using "read out loud" and "laugh aloud," if those are the forms you prefer. After all, this is an area where the authorities have shown very little consistency and insight.