There is a legitimate reason for your doctor asking you to say “ah” when examining your throat. This particular vowel sound keeps your tongue low in your mouth (out of the doctor’s way) and like all vowels, its sound can be held for a long period of time due to the vocal tract being open.
IPA (the International Phonetic Alphabet) is a system of symbols used by Speech-Language Pathologists to standardize the method for recording speech sounds produced by the patient. If one SLP transcribes a series of speech sounds using IPA, another SLP will easily be able to look at the notes and recognize precisely which sounds were produced. IPA can also be used to understand the pronunciation of words when learning a foreign language.
English, as you know, has 5 vowels: “a”, “e”, “i”, “o” and “u”. We also know that these vowels are produced in various ways depending on the word they appear in. These different sounds are represented in a vowel quadrilateral on the IPA chart. The “ah” sound is represented by the symbol in the Back-Low position on the chart below.
The vowel sounds on this chart are organized based on 4 criteria. They are the height of your tongue (high, mid, low), tongue advancement (front, central, or back in the mouth), tenseness (degree of muscle activity and duration of the sound) and lip configuration (whether or not your lips are rounded). You can see that so much goes in to the production of vowel sounds! A person with typically developed speech does these things without thinking about them. When training someone to make a particular sound, they can be instructed on where to position their tongue, etc.
It is important to realize that the number of speech sounds will not always be equal to the number of letters in a word. One symbol corresponds to one sound, NOT LETTER! For example the word “track” has 5 letters but only 4 sounds. It would be transcribed like this: /træk/. We essentially need to forget about spelling and focus on what we are hearing when we transcribe.
It would be pretty boring for me to give you a list of the sounds and examples of words that exemplify them, so here is the link to a great site that allows you to play around with the sounds. Thanks to my Psycholinguistics professor for sharing this with our class! Click on “monophthongs” at the top, then on either “front”, “central” or “back” to see the various vowel symbols. It also shows you what goes on in the mouth (oral cavity if you want to get technical) and vocal tract during the production of these vowel sounds. There are also examples of words in American English highlighting the sound you are focusing on.
Dialects also play a huge role on the way words sound. Since you focus on the sound when you transcribe, you can get two different transcriptions of the same word when listening to a person from New York City and a person from Boston. There is no black-and-white transcription for a particular word. It all depends on the model’s pronunciation.