Have you noticed that it is harder to understand people on the telephone? And harder for them to understand you! That because of how sound works. Sounds have frequency (pitch) and intensity (loudness). The chart below shows the frequency (Hz) of specific sounds in speech and the softest levels (decibels) we hear them.
Telephones transmit frequencies of 300-3400 Hz, so you can see that certain sounds like /f/, /s/, /th/ are not transmitted. We don’t hear those sounds, but our brain fills them in and we think we hear them. We do this because of the context of the sentence or phrase. If you asked some one if they had anything good to eat this week and they said, “I had soup on Sunday”, you wouldn’t really hear the /s/ in soup or Sunday, but your brain would fill in the missing sound.
Problems arise when there is no context to help us, such as when one is given a name for the first time, an address or phone number.
For accented speakers the problems can occur on both sides of the phone. The accented speaker may not be as quick to “fill in” the correct sound because their limited English vocabulary or understanding of grammar slows them down. The native English speaker listening to an accented speaker has difficulty “filling in” words and sounds due to the ways the accent changes the speech. Additionally, the accented speaker may not use the “expected” word because they speak English as a second language.
For these reasons, an accented speaker may avoid talking on the phone and prefer written communication. Improving pronunciation of English through accent modification will increase confidence on the phone and insure more successful phone communication professionally and personally.