How to pronounce American English: Voiced vs. voiceless sounds

Vowel sounds are always voiced (the vocal folds buzz when saying these sounds). Consonant sounds can be either voiced or voiceless, and they come in pairs called cognates.  Why is it helpful to know about voiced and voiceless cognate sounds?  A frequent error in accented speech is the de-voicing of final consonants.  What this means is that the speaker does not use any or enough voicing (buzzing of the vocal folds) on the last sound of the word, so it sounds like the voiceless cognate.  This occurs for various reasons.  The speaker's native language may not have words that end with voiced sounds.  The speaker may be listening to American English speech, and not really hear or notice the voicing on the ends of words when listening to Americans.  Or the voiced sounds might be part of a group of consonants at the end of the word, and the challenge of producing this consonant cluster makes using correct voicing difficult.

Whatever the reason, attention to this error is important because you may sound like you are saying a different word than you are.  Your listener will likely understand based on the context, but having to interpret what you are saying puts an increased cognitive load on the listener, and they may struggle to follow what you are saying as a result.

The pairs of consonant sounds are as follows:
voiceless:  t    voiced:  d      Examples:  to, do
voiceless:  p    voiced:  b     Examples:  poor, boor
voiceless:  k    voiced:  g      Examples:  came, game
voiceless:  f    voiced: v        Examples:  fan, van
voiceless:  s    voiced:  z       Examples:  sip, zip
voiceless:  sh    voiced:  zh    Examples: mesh, measure
voiceless:  ch    voiced:  j       Examples:  choke, joke
voiceless:  th (IPA /θ/)  voiced th (IPA /ð/)  Examples:  thigh, thy

One helpful way to ensure you are pronouncing the final consonant with the correct voicing is to lengthen the vowel sound before the voiced consonant.  For example, when we say the word "bead," we hold the vowel ee for a little step down because the "d" is voiced.  When we say the word "beat" we don't hold the vowel ee for any additional length.  Listen to the pairs below and try making a longer vowel and voiced sound to end the word.  Then try some of the words in the list on your own.

beat   bead
bop    Bob
pick    pig
leaf     leave
bus     buzz
mesh    measure
rich    ridge
breath    breathe