If I wanted to sing the ABCs, how would I do it in Esperanto?
In all seriousness though, English letters are generally referred to by a name (Ae, Bee, See, ..., Aech, Eye, Jay). But I can't really say "Aech with a hat" or "Aech-ecks" (hx) for Ĥ.
So what are the names of the following letters?
Ĉ Ĝ Ĥ Ĵ Ŝ Ŭ
You simply add an -o noise to the end of letter. So, for these letters, you would pronounce it as follows:
Ĉo, Ĝo, Ĥo, Ĵo, Ŝo, Ŭo
This is how it was presented to me, at least. I will also include a link to the video that actually taught me this so you can hear how it's pronounced here.
When wanting to say multiple letters, you should still add the -oj ending to each letter, as shown below:
Ĉo-oj, Ĝo-oj, Ĥo-oj, Ĵo-oj, Ŝo-oj, Ŭo-oj
P.S. After reading the other responses to this question, the question really boils down to Can you communicate a letter clearly? In my opinion, I think any one of the ways presented here would work, but to avoid confusion, you could say:
La literoj Ho, O, Mo, A, Ĉo, O
By doing this, the listener will not confuse them for other words, as they know you are listing off letters.
The most common procedure by far is to add -o to every consonant:
a, bo, co, ĉo, do, e, fo, go, ĝo, ho, ĥo, i, jo, ĵo, ko, lo, mo, no, o, po, ro, so, ŝo, to, u, ŭo, vo, zo
These are the names given at the start of the Ekzercaro in the Fundamento de Esperanto. The non-Esperanto letters in the Latin alphabet are called: Q kuo, W duobla vo, X ikso, Y ipsilono.
Hence, the Esperanto word for ABC is aboco.
The system has the virtue of being easy to remember for adult learners, but it poses problems, especially in maths and science. For example, the name ro clashes with the Greek letter rho, the word do ("therefore") clashes with the letter do, and structural formulas in chemistry are hard to distinguish when read out. In 1949, F. J. Belinfante asked readers of Scienca Revuo whether they considered the system usable for all purposes; three-quarters of respondents said no. As a result there have been plenty of alternative proposals, but none are widely used yet. To give you an idea of what they look like, here are four of them.
The lexicographer Gaston Waringhien suggested adding -a to voiced consonants and -o to unvoiced (with some exceptions):
a, ba, co, ĉo, da, e, fo, ga, ĝa, ha, ĥo, i, jo, ĵa, ko, lo, mo, na, o, po, ra, so, ŝo, to, u, ŭo, va, za
The physicist Frederik Belinfante recommended the following for scientific work, based on 17 natural-language alphabets:
a, be, ce, de, e, ef, ge, haĉ, i, jot, ka, el, em, en, o, pe, ku, er, es, te, u, vi, ŭe, iks, ŭaj, zet
Alternatives: ha, je, me, vaŭ, etc. For the Esperanto letters: ĉe, ĝo, ĥa, ĵe, ŝa, ŭo
The following alphabet-song was suggested by the poet Kálmán Kalocsay:
a, be, ce, de, e, ef, ge, ha, / i, je, ka, el, om, en, o, pa, / er, es, ta, u, ve, ĉa, ĝe, / ĥi kaj ĵi, eŝ, ŭo kaj ze, / plus ku, ikso, ipsilono, / jen la abece-kolono.
A very recent one, used by an accessibility add-on for Firefox, avoids clashing with any actual Esperanto words:
a, be, ce, ĉa, di, e, ef, ge, ĝe, ha, ĥi, i, jo, ĵi, ka, lo, om, no, o, pa, kuo, er, es, eŝ, ta, u, ŭo, ve, vavo, ikso, ipsilopo, ze.
Are you asking about how to say them in English or Esperanto.
In Esperanto, as has been said, the official method is to say the sound of the letter followed by the -o sound. By the way, it fits to the traditional "Twinkle Twinkle" melody if you break it down like this.
When talking about Esperanto in English, I'll often just use the Esperanto names. "Eĥo is spelled Eee-ĥo-oh." You can also say "Eĥo is spelled Eee--Aich-hat--Oh."
The recommended system is as follows:
Zamenhof simply tacked an -o onto each consonant to create the name of the letter, with the vowels representing themselves: a, bo, co, ĉo, do, e, fo, etc. The diacritics are frequently mentioned overtly. For instance, ĉ may be called ĉo ĉapela or co ĉapela, from ĉapelo (a hat), and ŭ may be called ŭo luneta or u luneta, from luno (a moon) plus the diminutive -et-. This is the only system that is widely accepted and in practical use.
So, you have three possibilities:
There is no established standard for naming letters with the "hat" and several different names can be found, e.g. ĉapelita ĉ, ĉo ĉapelo and ĉo ĉapela.
In my opinion, it's best to mention the "hats" explicitly. For example, there are many languages that have either only the ĥ-sound or only the h-sound. Given that ĥ is infrequent, there are few opportunities to practice this distinction, and many Esperanto speakers may have a problem telling these two sounds apart. When you say ĥo ĉapela, there will be no way to be misunderstood.
Additionally, <q> is called kuo, <x> is called ikso and <y> is called ipsilono. The letter <w> has several names, but vavo is the most practical one. Its other names are simply too cumbersome when reading common abbreviations, such as "www" (it's definitely easier to say vavo-vavo-vavo than duobla vo - duobla vo - duobla vo).
