I heard people saying that if you put your finger on your throat you would be able to feel voiced sound vibrates and voiceless sound doesn't. I tried it but both sounds seem the same to me. So did I do wrong, and how to "feel" this correctly? Thanks
There are several ways to feel the difference between a voiced and unvoiced sound. You can put your hand on your throat (not a bad method); you can put the whole of the palm of your hand on the top of your head (a very good method); you can try sticking your finger in your ear - or even one finger in each ear ( works very well for a lot of people).
Now, we want a good pair of sounds to contrast. Because we are just learning to tell the difference, we need a sound where it is easier to feel the vibration. To help us do this a) the sound needs to be a type of sound that we can make for a long time, b) it needs to be a sound where the vibration is felt strongly in the bone and other tissue in the head.
So short consonants such as the plosives /p, t, k, b, d, g/ are not a good choice here. Vowels aren't good because the vibration doesn't transmit to the facial tissue because the air escapes freely through the mouth. Nasals sounds such as /m, n, ŋ/ are usable, but they are not great. With these sounds we definitely can feel some vibration, but it's not very strong. These are sonorant sounds, and because the air leaves the nose freely the vibration doesn't transmit to the other tissue very well.
What we need is fricatives. These are sounds where we make a blockage in the mouth and then force air through a small hole in that blockage. These are the voiced fricative sounds in English:
- /v/ as in very
- /ð/ as in the
- /z/ as in zoo
- /ʒ/ as in television
Now you need some good unvoiced sounds to compare with. Here are the unvoiced fricatives in English:
- /f/ as in fine
- /θ/ as in think
- /s/ as in stop
- /ʃ/ as in shower
Now choose one of the sounds in the first group. Choose a sound you can make very well. If you're not a native speaker, choose a sound that is exactly the same in your first language and in English, if possible. Now, say that sound for a very long time, maybe five seconds. For example "zzzzzzzzzzzzzzzzzzzzz". Put your hand on your head and try it; put your finger in your ear and try it; put your hand on your throat and try it. Now, can your hum a tune using this sound? If you are making the sound correctly, you should be able to do this. Now try with some of the other voiced sounds too. Hopefully you will be able to feel the vibration using one of these three methods.
Right, after you've done that try the exactly same thing with an unvoiced sound, maybe "sssssssssss", for example. Experiment with the different methods for feeling the vibrations. This time you won't be able to feel any vibration. Also, if you are making the sound correctly, you won't be able to hum a tune with it. These sounds don't have any pitch. There is no musical note present. This pitch or musical tone comes directly from the vocal fold vibration.
Lastly, choose the most successful method you used for feeling the vibration. Switch between different sounds. The difference should become clearer to you now.
Most likely, I think, is that the supposedly voiced sounds you have trouble with are not actually voiced. Just because they are classified as voiced, it doesn't mean the voiced obstruent phonemes of English are always actually voiced. According to The Sound Pattern of English, which is a standard reference for phonetic features, obstruents by definition have a tendency to be voiceless -- there is an obstruction in the vocal tract sufficient to prevent spontaneous voicing because of the air pressure that develops behind the obstruction and slows the air passing up through the glottis. To produce voice, the vocal cords have to have considerable air passing through, which pulls them together and blows them apart, periodically.
The obstruents are the non-nasal stops and the fricatives. Unless some special measures are taken to maintain the air speed past the vocal cords, the air speed will be slowed down so much that the vibration of the vocal cords ceases, and there is no voicing. There are several measures that can be taken to keep air flowing and maintain voicing for obstruents: loosen the cheeks to let them bulge out, lower the jaw to create more volume in the mouth, pull the glottis down (which can produce implosive sounds).
But the bottom line is that often obstruents will be devoiced. In English, at the end of a word, and when there is no following voiced sound, b d g are often voiceless. Even in a phonetic transcription, they are generally still written down as if they were voiced, but don't be fooled. There may be no actual vocal cord vibration, so if you don't hear the voice, that may very well be because it is not there.