I have seen lately many questions related to the pronunciation of the schwa (ə) sound. Today, I again found this question, What exactly is the "schwa" sound?, at EL&U, so I wanted to ask how the 'schwa' sound is pronounced.
I believe that schwa (ə) is something a bit mystery to many ELLs. The number of questions here, at EL&U, and around the web seems to indicate so. If you are learning English as a second language, and your language has no such concept as schwa, I hope my answer could help you at least at some level.
If you look up words in dictionary, soon you will find this inverted e character, ə. Then you soon may come to learn that this strange-looking character is called schwa. Then soon, you might get confused that some dictionaries transcribed this schwa sound differently. But more importantly, you usually found that native speakers do not pronounce those words exactly the same way they are written in dictionaries. Or at least, to you, it appears so. For example, according to one question I found here,
In spoken English, according to linguists and many researchers, when vowel sounds are sorted by number of occurrences, the schwa sound will be at the top of the chart, so it is very important for ELLs to learn how to hear and how to pronounce this schwa sound properly. (You can find an example of results of such researches here.)
My tips for dealing with the schwa sound in listening
Knowing which syllables and which words to stress is very important in spoken English. And, because the stress at word level is rather fixed, dictionaries usually transcribe the majority, if not all, of unstressed syllables as schwa (ə). (Actually, there are much more subtle details. For example, most modern dictionaries will also transcribe some of these unstressed syllables as [ɪ], but that deserves a different question.)
Now you might wonder why I call "schwa" the center vowel.
The answer is because it is THE center vowel. Or, to be more technically precise, schwa is the mid-central vowel. If you look at the IPA chart below, you will see that the schwa sits exactly in the middle of the chart.
In English, when the sound of any other vowel is reduced to its weak form, the sound will be shifted toward this center sound, the schwa (ə) sound. (There are exceptions such the [i] sound (e.g. bit, spit), or the [e] sound (e.g. bet, set) which will be shifted to the ɪ sound, rather than all the way to the schwa.)
Most of unstressed syllables will be reduced to a schwa. Unstressed words will also be shifted toward the schwa too, but not as much as in unstressed syllables. These unstressed words are sometimes said that they are pronounced in their weak forms. A good example of these weak forms is the word and. When it is fully pronounced (strong form), it will sound /ænd/. When it is unstressed (weak form), it will sound more like /(ə)n(d)/.
How to make this 'schwa' sound
I hope that the explanation above could help you to understand why schwa can sound like many sounds. It is exactly because it can be many sounds. You just have to think of schwa as something being reduced toward the center sound.
To make schwa sounds, you just need to reduce the sound of the vowel you thought it is supposed to sound like, and reduce it a lot, to the point that it almost loses the quality of the original vowel you first thought. For example, the first syllable of the word accord has the schwa sound. But many ELLs (including myself, once upon a time) think that it should be pronounced /ack-cord/, and found that when a native speaker says this word, it sounds nothing like /ack-cord/. It shouldn't sound /ack-cord/, of course, because it actually is /ə-kord/. To pronounce words with schwa sounds correctly, just remember to reduce the vowels by shifting them toward the center vowel, as much as you can.
This begs the question: how does this center vowel sound like?
Here is my trick to produce this center vowel.
First, start by having your mouth closed, but not tense. Relax your face. Relax your jaw. Relax your tongue. Just keep relaxing.
Then, open your mouth by dropping your jaw moderately. Do not move your tongue. Your tongue should rest in your mouth relaxingly. Your tongue does nothing. Make sure that your mouth open wider than when you say the letter E, but narrower than when you say Ah! (the sound that your dentist will ask you to make). Do not force your muscles around your lips. Do not try to form your lips into any shape. Just keep relaxed.
Then, make a sound.
And, there you have it! That's your center vowel. That's your ideal schwa!
Just remember that your tongue has nothing to do with this sound. It should rest comfortably in your mouth. Do not lift it. Do not protrude it. Do not hold it backward. Do not curl it up. Your jaw also does nothing much. Do not tense it. Do not move it forward or backward. Just drop it gently. Just keep relaxing.
Remember to open your mouth moderately. Open it too much and you will get a sort of /ah/ sound. Open it too less and you will get a sort of /i/ (letter E) sound. (If you look at the IPA chart, the /i/ sound is at the "close" position, and the /ah/ sound is at the "open" position. In fact, the vertical arrangement of the IPA chart is exactly in the inverted proportion to how much you open your mouth!)
This is a long post for me, but I hope it is useful to you. It might a bit too long to read, but I hope that it is worth your time reading it. And, above all, I hope that it can help you find your own schwa sound.
Two sounds in English are commonly identified as schwa, and, as a native English speaker, while I acknowledge that they have similar qualities, I find them different.
The first is the vowel that occurs in most unstressed English syllables, e.g. the first syllable of about. This sound I produce as follows: my lips leave only a small opening, but I'm not using any muscles to constrict that opening (contrast "a" where my lips are more open or "o" where I am using muscles to round my lips a little). My tongue is in its "resting" position; neither raised nor pulled back. Most importantly, I don't make the sound for very long. We could call this the "lazy vowel." The idea is that in unstressed syllables, we do the minimal amount of work to make a vowel! It is extremely important to master this sound when speaking English.
Some speakers have two different sounds that go into unstressed vowels, so that the middle syllable of habitate is not quite this schwa; however, at least in my dialect, there is no distinction. Also, most literate English speakers will, if you ask them to repeat a word slowly, mislead you by accenting all the syllables: "I said "opp-or-tun-it-y" -if they do this, they won't make a schwa in the "or" or "it" syllables, but that is the sound we make when we say the word at a normal pace.
The second sound that is sometimes called schwa is a vowel that occurs in a few words and is not spelled consistently, but usually spelled [oo] or [u], as in hood or put. It always occurs in stressed syllables and never in unstressed syllables. I prefer to analyze this vowel as /ʊ/ and not as schwa, but some call it schwa (there are no minimal pairs distinguishing them, so this is not unreasonable). It is less important that you master this second sound. To make it, I make it similarly to the sound described in the previous paragraph, but the duration is longer, and there is significantly more muscular tension in the lips (they are rounded to roughly the "o" position).
The schwa is two things.
To phonologists, it is a vowel sound between e and a. The tongue is lower than e, but higher than a. This is independent of any connections with the English language.
To users of English dictionaries, the schwa it is an upside-down e notation which doesn't denote one specific phoneme but different sounds in different dialects of English. There are differences among dialects of English with regard what sound occurs. In some dialects, it becomes an "R-colored vowel".
Dictionaries use one symbol, because they use a phonemic rather than phonetic transcription system, which tries to bridge the differences among the major dialects of English in a single notation.
So if you see the schwa notation, you have to substitute the appropriate sound for your dialect. For instance, the word "water" in the dialects used in England has a more or less pure schwa on the end, whereas in most North American dialects (not all), it becomes rhotic ("a rolling R").
Short answer: Go to this URL: http://www.thefreedictionary.com/bevel Click on the speaker icon. The second vowel in that word is the schwa sound.
If that's not clear, try this one: http://www.thefreedictionary.com/angle The second vowel in that is also a schwa.
If you listen to both, maybe you can hear the similarity in the sound.