A question of sound, not sight: “A” or “an”

Would you say an NHL referee or a NHL referee? It's an NHL referee. The indefinite article an is used before all vowel sounds except the long u sound (a united stand) and before the silent h (an honourable politician). And since the first letter of NHL makes the vowel sound en, it takes the article an.

Here are some questions to test your knowledge.

1. Placeholder for the answer ATV (all-terrain vehicle)
2. Placeholder for the answer audit review
3. Placeholder for the answer hard disk
4. Placeholder for the answer UN (United Nations) conference
5. Placeholder for the answer NDP (New Democratic Party) member
6. Placeholder for the answer hearing
7. Placeholder for the answerHD (high-definition) television
8. Placeholder for the answer NATO (North Atlantic Treaty Organization) publication
9. Placeholder for the answer CPR (cardiopulmonary resuscitation) course
10. Placeholder for the answer FTA (free trade area) tariff
  

Note: Adapted from Charles Skeete's article "A Question of Sound, Not Sight" in Terminology Update, Vol. 29, No. 3, 1996, p. 14.